Add m-esr52 at 52.6.0

380 files changed, 54040 insertions, 0 deletions

diff --git a/layout/xul/BoxObject.cpp b/layout/xul/BoxObject.cpp
new file mode 100644
index 0000000000..6636a6d622
--- /dev/null
+++ b/layout/xul/BoxObject.cpp
@@ -0,0 +1,614 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/BoxObject.h"
+#include "nsCOMPtr.h"
+#include "nsIDocument.h"
+#include "nsIPresShell.h"
+#include "nsPresContext.h"
+#include "nsIContent.h"
+#include "nsContainerFrame.h"
+#include "nsIDocShell.h"
+#include "nsReadableUtils.h"
+#include "nsDOMClassInfoID.h"
+#include "nsView.h"
+#ifdef MOZ_XUL
+#include "nsIDOMXULElement.h"
+#else
+#include "nsIDOMElement.h"
+#endif
+#include "nsLayoutUtils.h"
+#include "nsISupportsPrimitives.h"
+#include "nsSupportsPrimitives.h"
+#include "mozilla/dom/Element.h"
+#include "nsComponentManagerUtils.h"
+#include "mozilla/dom/BoxObjectBinding.h"
+
+// Implementation /////////////////////////////////////////////////////////////////
+
+namespace mozilla {
+namespace dom {
+
+// Static member variable initialization
+
+// Implement our nsISupports methods
+NS_IMPL_CYCLE_COLLECTION_CLASS(BoxObject)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(BoxObject)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(BoxObject)
+
+// QueryInterface implementation for BoxObject
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(BoxObject)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsIBoxObject)
+  NS_INTERFACE_MAP_ENTRY(nsPIBoxObject)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(BoxObject)
+  // XXX jmorton: why aren't we unlinking mPropertyTable?
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(BoxObject)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
+  if (tmp->mPropertyTable) {
+    for (auto iter = tmp->mPropertyTable->Iter(); !iter.Done(); iter.Next()) {
+      cb.NoteXPCOMChild(iter.UserData());
+    }
+  }
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(BoxObject)
+
+// Constructors/Destructors
+BoxObject::BoxObject()
+  : mContent(nullptr)
+{
+}
+
+BoxObject::~BoxObject()
+{
+}
+
+NS_IMETHODIMP
+BoxObject::GetElement(nsIDOMElement** aResult)
+{
+  if (mContent) {
+    return CallQueryInterface(mContent, aResult);
+  }
+
+  *aResult = nullptr;
+  return NS_OK;
+}
+
+// nsPIBoxObject //////////////////////////////////////////////////////////////////////////
+
+nsresult
+BoxObject::Init(nsIContent* aContent)
+{
+  mContent = aContent;
+  return NS_OK;
+}
+
+void
+BoxObject::Clear()
+{
+  mPropertyTable = nullptr;
+  mContent = nullptr;
+}
+
+void
+BoxObject::ClearCachedValues()
+{
+}
+
+nsIFrame*
+BoxObject::GetFrame(bool aFlushLayout)
+{
+  nsIPresShell* shell = GetPresShell(aFlushLayout);
+  if (!shell)
+    return nullptr;
+
+  if (!aFlushLayout) {
+    // If we didn't flush layout when getting the presshell, we should at least
+    // flush to make sure our frame model is up to date.
+    // XXXbz should flush on document, no?  Except people call this from
+    // frame code, maybe?
+    shell->FlushPendingNotifications(Flush_Frames);
+  }
+
+  // The flush might have killed mContent.
+  if (!mContent) {
+    return nullptr;
+  }
+
+  return mContent->GetPrimaryFrame();
+}
+
+nsIPresShell*
+BoxObject::GetPresShell(bool aFlushLayout)
+{
+  if (!mContent) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIDocument> doc = mContent->GetUncomposedDoc();
+  if (!doc) {
+    return nullptr;
+  }
+
+  if (aFlushLayout) {
+    doc->FlushPendingNotifications(Flush_Layout);
+  }
+
+  return doc->GetShell();
+}
+
+nsresult
+BoxObject::GetOffsetRect(nsIntRect& aRect)
+{
+  aRect.SetRect(0, 0, 0, 0);
+
+  if (!mContent)
+    return NS_ERROR_NOT_INITIALIZED;
+
+  // Get the Frame for our content
+  nsIFrame* frame = GetFrame(true);
+  if (frame) {
+    // Get its origin
+    nsPoint origin = frame->GetPositionIgnoringScrolling();
+
+    // Find the frame parent whose content is the document element.
+    Element* docElement = mContent->GetComposedDoc()->GetRootElement();
+    nsIFrame* parent = frame->GetParent();
+    for (;;) {
+      // If we've hit the document element, break here
+      if (parent->GetContent() == docElement) {
+        break;
+      }
+
+      nsIFrame* next = parent->GetParent();
+      if (!next) {
+        NS_WARNING("We should have hit the document element...");
+        origin += parent->GetPosition();
+        break;
+      }
+
+      // Add the parent's origin to our own to get to the
+      // right coordinate system
+      origin += next->GetPositionOfChildIgnoringScrolling(parent);
+      parent = next;
+    }
+
+    // For the origin, add in the border for the frame
+    const nsStyleBorder* border = frame->StyleBorder();
+    origin.x += border->GetComputedBorderWidth(NS_SIDE_LEFT);
+    origin.y += border->GetComputedBorderWidth(NS_SIDE_TOP);
+
+    // And subtract out the border for the parent
+    const nsStyleBorder* parentBorder = parent->StyleBorder();
+    origin.x -= parentBorder->GetComputedBorderWidth(NS_SIDE_LEFT);
+    origin.y -= parentBorder->GetComputedBorderWidth(NS_SIDE_TOP);
+
+    aRect.x = nsPresContext::AppUnitsToIntCSSPixels(origin.x);
+    aRect.y = nsPresContext::AppUnitsToIntCSSPixels(origin.y);
+
+    // Get the union of all rectangles in this and continuation frames.
+    // It doesn't really matter what we use as aRelativeTo here, since
+    // we only care about the size. Using 'parent' might make things
+    // a bit faster by speeding up the internal GetOffsetTo operations.
+    nsRect rcFrame = nsLayoutUtils::GetAllInFlowRectsUnion(frame, parent);
+    aRect.width = nsPresContext::AppUnitsToIntCSSPixels(rcFrame.width);
+    aRect.height = nsPresContext::AppUnitsToIntCSSPixels(rcFrame.height);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+BoxObject::GetScreenPosition(nsIntPoint& aPoint)
+{
+  aPoint.x = aPoint.y = 0;
+
+  if (!mContent)
+    return NS_ERROR_NOT_INITIALIZED;
+
+  nsIFrame* frame = GetFrame(true);
+  if (frame) {
+    nsIntRect rect = frame->GetScreenRect();
+    aPoint.x = rect.x;
+    aPoint.y = rect.y;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetX(int32_t* aResult)
+{
+  nsIntRect rect;
+  GetOffsetRect(rect);
+  *aResult = rect.x;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetY(int32_t* aResult)
+{
+  nsIntRect rect;
+  GetOffsetRect(rect);
+  *aResult = rect.y;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetWidth(int32_t* aResult)
+{
+  nsIntRect rect;
+  GetOffsetRect(rect);
+  *aResult = rect.width;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetHeight(int32_t* aResult)
+{
+  nsIntRect rect;
+  GetOffsetRect(rect);
+  *aResult = rect.height;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetScreenX(int32_t *_retval)
+{
+  nsIntPoint position;
+  nsresult rv = GetScreenPosition(position);
+  if (NS_FAILED(rv)) return rv;
+  *_retval = position.x;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetScreenY(int32_t *_retval)
+{
+  nsIntPoint position;
+  nsresult rv = GetScreenPosition(position);
+  if (NS_FAILED(rv)) return rv;
+  *_retval = position.y;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetPropertyAsSupports(const char16_t* aPropertyName, nsISupports** aResult)
+{
+  NS_ENSURE_ARG(aPropertyName && *aPropertyName);
+  if (!mPropertyTable) {
+    *aResult = nullptr;
+    return NS_OK;
+  }
+  nsDependentString propertyName(aPropertyName);
+  mPropertyTable->Get(propertyName, aResult); // Addref here.
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::SetPropertyAsSupports(const char16_t* aPropertyName, nsISupports* aValue)
+{
+  NS_ENSURE_ARG(aPropertyName && *aPropertyName);
+
+  if (!mPropertyTable) {
+    mPropertyTable = new nsInterfaceHashtable<nsStringHashKey,nsISupports>(4);
+  }
+
+  nsDependentString propertyName(aPropertyName);
+  mPropertyTable->Put(propertyName, aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetProperty(const char16_t* aPropertyName, char16_t** aResult)
+{
+  nsCOMPtr<nsISupports> data;
+  nsresult rv = GetPropertyAsSupports(aPropertyName,getter_AddRefs(data));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (!data) {
+    *aResult = nullptr;
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsISupportsString> supportsStr = do_QueryInterface(data);
+  if (!supportsStr) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return supportsStr->ToString(aResult);
+}
+
+NS_IMETHODIMP
+BoxObject::SetProperty(const char16_t* aPropertyName, const char16_t* aPropertyValue)
+{
+  NS_ENSURE_ARG(aPropertyName && *aPropertyName);
+
+  nsDependentString propertyName(aPropertyName);
+  nsDependentString propertyValue;
+  if (aPropertyValue) {
+    propertyValue.Rebind(aPropertyValue);
+  } else {
+    propertyValue.SetIsVoid(true);
+  }
+
+  nsCOMPtr<nsISupportsString> supportsStr(do_CreateInstance(NS_SUPPORTS_STRING_CONTRACTID));
+  NS_ENSURE_TRUE(supportsStr, NS_ERROR_OUT_OF_MEMORY);
+  supportsStr->SetData(propertyValue);
+
+  return SetPropertyAsSupports(aPropertyName,supportsStr);
+}
+
+NS_IMETHODIMP
+BoxObject::RemoveProperty(const char16_t* aPropertyName)
+{
+  NS_ENSURE_ARG(aPropertyName && *aPropertyName);
+
+  if (!mPropertyTable) return NS_OK;
+
+  nsDependentString propertyName(aPropertyName);
+  mPropertyTable->Remove(propertyName);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetParentBox(nsIDOMElement * *aParentBox)
+{
+  *aParentBox = nullptr;
+  nsIFrame* frame = GetFrame(false);
+  if (!frame) return NS_OK;
+  nsIFrame* parent = frame->GetParent();
+  if (!parent) return NS_OK;
+
+  nsCOMPtr<nsIDOMElement> el = do_QueryInterface(parent->GetContent());
+  *aParentBox = el;
+  NS_IF_ADDREF(*aParentBox);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetFirstChild(nsIDOMElement * *aFirstVisibleChild)
+{
+  *aFirstVisibleChild = nullptr;
+  nsIFrame* frame = GetFrame(false);
+  if (!frame) return NS_OK;
+  nsIFrame* firstFrame = frame->PrincipalChildList().FirstChild();
+  if (!firstFrame) return NS_OK;
+  // get the content for the box and query to a dom element
+  nsCOMPtr<nsIDOMElement> el = do_QueryInterface(firstFrame->GetContent());
+  el.swap(*aFirstVisibleChild);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetLastChild(nsIDOMElement * *aLastVisibleChild)
+{
+  *aLastVisibleChild = nullptr;
+  nsIFrame* frame = GetFrame(false);
+  if (!frame) return NS_OK;
+  return GetPreviousSibling(frame, nullptr, aLastVisibleChild);
+}
+
+NS_IMETHODIMP
+BoxObject::GetNextSibling(nsIDOMElement **aNextOrdinalSibling)
+{
+  *aNextOrdinalSibling = nullptr;
+  nsIFrame* frame = GetFrame(false);
+  if (!frame) return NS_OK;
+  nsIFrame* nextFrame = frame->GetNextSibling();
+  if (!nextFrame) return NS_OK;
+  // get the content for the box and query to a dom element
+  nsCOMPtr<nsIDOMElement> el = do_QueryInterface(nextFrame->GetContent());
+  el.swap(*aNextOrdinalSibling);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+BoxObject::GetPreviousSibling(nsIDOMElement **aPreviousOrdinalSibling)
+{
+  *aPreviousOrdinalSibling = nullptr;
+  nsIFrame* frame = GetFrame(false);
+  if (!frame) return NS_OK;
+  nsIFrame* parentFrame = frame->GetParent();
+  if (!parentFrame) return NS_OK;
+  return GetPreviousSibling(parentFrame, frame, aPreviousOrdinalSibling);
+}
+
+nsresult
+BoxObject::GetPreviousSibling(nsIFrame* aParentFrame, nsIFrame* aFrame,
+                              nsIDOMElement** aResult)
+{
+  *aResult = nullptr;
+  nsIFrame* nextFrame = aParentFrame->PrincipalChildList().FirstChild();
+  nsIFrame* prevFrame = nullptr;
+  while (nextFrame) {
+    if (nextFrame == aFrame)
+      break;
+    prevFrame = nextFrame;
+    nextFrame = nextFrame->GetNextSibling();
+  }
+
+  if (!prevFrame) return NS_OK;
+  // get the content for the box and query to a dom element
+  nsCOMPtr<nsIDOMElement> el = do_QueryInterface(prevFrame->GetContent());
+  el.swap(*aResult);
+  return NS_OK;
+}
+
+nsIContent*
+BoxObject::GetParentObject() const
+{
+  return mContent;
+}
+
+JSObject*
+BoxObject::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return BoxObjectBinding::Wrap(aCx, this, aGivenProto);
+}
+
+Element*
+BoxObject::GetElement() const
+{
+  return mContent && mContent->IsElement() ? mContent->AsElement() : nullptr;
+}
+
+int32_t
+BoxObject::X()
+{
+  int32_t ret = 0;
+  GetX(&ret);
+  return ret;
+}
+
+int32_t
+BoxObject::Y()
+{
+  int32_t ret = 0;
+  GetY(&ret);
+  return ret;
+}
+
+int32_t
+BoxObject::GetScreenX(ErrorResult& aRv)
+{
+  int32_t ret = 0;
+  aRv = GetScreenX(&ret);
+  return ret;
+}
+
+int32_t
+BoxObject::GetScreenY(ErrorResult& aRv)
+{
+  int32_t ret = 0;
+  aRv = GetScreenY(&ret);
+  return ret;
+}
+
+int32_t
+BoxObject::Width()
+{
+  int32_t ret = 0;
+  GetWidth(&ret);
+  return ret;
+}
+
+int32_t
+BoxObject::Height()
+{
+  int32_t ret = 0;
+  GetHeight(&ret);
+  return ret;
+}
+
+already_AddRefed<nsISupports>
+BoxObject::GetPropertyAsSupports(const nsAString& propertyName)
+{
+  nsCOMPtr<nsISupports> ret;
+  GetPropertyAsSupports(PromiseFlatString(propertyName).get(), getter_AddRefs(ret));
+  return ret.forget();
+}
+
+void
+BoxObject::SetPropertyAsSupports(const nsAString& propertyName, nsISupports* value)
+{
+  SetPropertyAsSupports(PromiseFlatString(propertyName).get(), value);
+}
+
+void
+BoxObject::GetProperty(const nsAString& propertyName, nsString& aRetVal, ErrorResult& aRv)
+{
+  nsCOMPtr<nsISupports> data(GetPropertyAsSupports(propertyName));
+  if (!data) {
+    return;
+  }
+
+  nsCOMPtr<nsISupportsString> supportsStr(do_QueryInterface(data));
+  if (!supportsStr) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  supportsStr->GetData(aRetVal);
+}
+
+void
+BoxObject::SetProperty(const nsAString& propertyName, const nsAString& propertyValue)
+{
+  SetProperty(PromiseFlatString(propertyName).get(), PromiseFlatString(propertyValue).get());
+}
+
+void
+BoxObject::RemoveProperty(const nsAString& propertyName)
+{
+  RemoveProperty(PromiseFlatString(propertyName).get());
+}
+
+already_AddRefed<Element>
+BoxObject::GetParentBox()
+{
+  nsCOMPtr<nsIDOMElement> el;
+  GetParentBox(getter_AddRefs(el));
+  nsCOMPtr<Element> ret(do_QueryInterface(el));
+  return ret.forget();
+}
+
+already_AddRefed<Element>
+BoxObject::GetFirstChild()
+{
+  nsCOMPtr<nsIDOMElement> el;
+  GetFirstChild(getter_AddRefs(el));
+  nsCOMPtr<Element> ret(do_QueryInterface(el));
+  return ret.forget();
+}
+
+already_AddRefed<Element>
+BoxObject::GetLastChild()
+{
+  nsCOMPtr<nsIDOMElement> el;
+  GetLastChild(getter_AddRefs(el));
+  nsCOMPtr<Element> ret(do_QueryInterface(el));
+  return ret.forget();
+}
+
+already_AddRefed<Element>
+BoxObject::GetNextSibling()
+{
+  nsCOMPtr<nsIDOMElement> el;
+  GetNextSibling(getter_AddRefs(el));
+  nsCOMPtr<Element> ret(do_QueryInterface(el));
+  return ret.forget();
+}
+
+already_AddRefed<Element>
+BoxObject::GetPreviousSibling()
+{
+  nsCOMPtr<nsIDOMElement> el;
+  GetPreviousSibling(getter_AddRefs(el));
+  nsCOMPtr<Element> ret(do_QueryInterface(el));
+  return ret.forget();
+}
+
+} // namespace dom
+} // namespace mozilla
+
+// Creation Routine ///////////////////////////////////////////////////////////////////////
+
+using namespace mozilla::dom;
+
+nsresult
+NS_NewBoxObject(nsIBoxObject** aResult)
+{
+  NS_ADDREF(*aResult = new BoxObject());
+  return NS_OK;
+}
diff --git a/layout/xul/BoxObject.h b/layout/xul/BoxObject.h
new file mode 100644
index 0000000000..ac3df420b6
--- /dev/null
+++ b/layout/xul/BoxObject.h
@@ -0,0 +1,91 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_BoxObject_h__
+#define mozilla_dom_BoxObject_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/ErrorResult.h"
+#include "nsCOMPtr.h"
+#include "nsIBoxObject.h"
+#include "nsPIBoxObject.h"
+#include "nsPoint.h"
+#include "nsAutoPtr.h"
+#include "nsHashKeys.h"
+#include "nsInterfaceHashtable.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsWrapperCache.h"
+#include "nsRect.h"
+
+class nsIFrame;
+class nsIPresShell;
+
+namespace mozilla {
+namespace dom {
+
+class Element;
+
+class BoxObject : public nsPIBoxObject,
+                  public nsWrapperCache
+{
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(BoxObject)
+  NS_DECL_NSIBOXOBJECT
+
+public:
+  BoxObject();
+
+  // nsPIBoxObject
+  virtual nsresult Init(nsIContent* aContent) override;
+  virtual void Clear() override;
+  virtual void ClearCachedValues() override;
+
+  nsIFrame* GetFrame(bool aFlushLayout);
+  nsIPresShell* GetPresShell(bool aFlushLayout);
+  nsresult GetOffsetRect(nsIntRect& aRect);
+  nsresult GetScreenPosition(nsIntPoint& aPoint);
+
+  // Given a parent frame and a child frame, find the frame whose
+  // next sibling is the given child frame and return its element
+  static nsresult GetPreviousSibling(nsIFrame* aParentFrame, nsIFrame* aFrame,
+                                     nsIDOMElement** aResult);
+
+  // WebIDL (wraps old impls)
+  nsIContent* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+
+  Element* GetElement() const;
+
+  int32_t X();
+  int32_t Y();
+  int32_t GetScreenX(ErrorResult& aRv);
+  int32_t GetScreenY(ErrorResult& aRv);
+  int32_t Width();
+  int32_t Height();
+
+  already_AddRefed<nsISupports> GetPropertyAsSupports(const nsAString& propertyName);
+  void SetPropertyAsSupports(const nsAString& propertyName, nsISupports* value);
+  void GetProperty(const nsAString& propertyName, nsString& aRetVal, ErrorResult& aRv);
+  void SetProperty(const nsAString& propertyName, const nsAString& propertyValue);
+  void RemoveProperty(const nsAString& propertyName);
+
+  already_AddRefed<Element> GetParentBox();
+  already_AddRefed<Element> GetFirstChild();
+  already_AddRefed<Element> GetLastChild();
+  already_AddRefed<Element> GetNextSibling();
+  already_AddRefed<Element> GetPreviousSibling();
+
+protected:
+  virtual ~BoxObject();
+
+  nsAutoPtr<nsInterfaceHashtable<nsStringHashKey,nsISupports> > mPropertyTable; //[OWNER]
+
+  nsIContent* mContent; // [WEAK]
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif
diff --git a/layout/xul/ContainerBoxObject.cpp b/layout/xul/ContainerBoxObject.cpp
new file mode 100644
index 0000000000..0464a6fec3
--- /dev/null
+++ b/layout/xul/ContainerBoxObject.cpp
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/ContainerBoxObject.h"
+#include "mozilla/dom/ContainerBoxObjectBinding.h"
+#include "nsCOMPtr.h"
+#include "nsIDocShell.h"
+#include "nsIContent.h"
+#include "nsIDocument.h"
+#include "nsIFrame.h"
+#include "nsSubDocumentFrame.h"
+
+namespace mozilla {
+namespace dom {
+  
+ContainerBoxObject::ContainerBoxObject()
+{
+}
+
+ContainerBoxObject::~ContainerBoxObject()
+{
+}
+
+JSObject*
+ContainerBoxObject::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return ContainerBoxObjectBinding::Wrap(aCx, this, aGivenProto);
+}
+
+already_AddRefed<nsIDocShell>
+ContainerBoxObject::GetDocShell()
+{
+  nsSubDocumentFrame *subDocFrame = do_QueryFrame(GetFrame(false));
+  if (subDocFrame) {
+    // Ok, the frame for mContent is an nsSubDocumentFrame, it knows how
+    // to reach the docshell, so ask it...
+    nsCOMPtr<nsIDocShell> ret;
+    subDocFrame->GetDocShell(getter_AddRefs(ret));
+    return ret.forget();
+  }
+
+  if (!mContent) {
+    return nullptr;
+  }
+
+  // No nsSubDocumentFrame available for mContent, try if there's a mapping
+  // between mContent's document to mContent's subdocument.
+
+  nsIDocument *doc = mContent->GetComposedDoc();
+
+  if (!doc) {
+    return nullptr;
+  }
+
+  nsIDocument *sub_doc = doc->GetSubDocumentFor(mContent);
+
+  if (!sub_doc) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIDocShell> result = sub_doc->GetDocShell();
+  return result.forget();
+}
+
+} // namespace dom
+} // namespace mozilla
+
+nsresult
+NS_NewContainerBoxObject(nsIBoxObject** aResult)
+{
+  NS_ADDREF(*aResult = new mozilla::dom::ContainerBoxObject());
+  return NS_OK;
+}
diff --git a/layout/xul/ContainerBoxObject.h b/layout/xul/ContainerBoxObject.h
new file mode 100644
index 0000000000..b3da97991c
--- /dev/null
+++ b/layout/xul/ContainerBoxObject.h
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ContainerBoxObject_h
+#define mozilla_dom_ContainerBoxObject_h
+
+#include "mozilla/dom/BoxObject.h"
+
+namespace mozilla {
+namespace dom {
+
+class ContainerBoxObject final : public BoxObject
+{
+public:
+  ContainerBoxObject();
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+
+  already_AddRefed<nsIDocShell> GetDocShell();
+
+private:
+  ~ContainerBoxObject();
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_ContainerBoxObject_h
diff --git a/layout/xul/ListBoxObject.cpp b/layout/xul/ListBoxObject.cpp
new file mode 100644
index 0000000000..435065f5b2
--- /dev/null
+++ b/layout/xul/ListBoxObject.cpp
@@ -0,0 +1,238 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/ListBoxObject.h"
+#include "nsCOMPtr.h"
+#include "nsIFrame.h"
+#include "nsGkAtoms.h"
+#include "nsIScrollableFrame.h"
+#include "nsListBoxBodyFrame.h"
+#include "ChildIterator.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/ListBoxObjectBinding.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_ISUPPORTS_INHERITED(ListBoxObject, BoxObject, nsIListBoxObject,
+                            nsPIListBoxObject)
+
+ListBoxObject::ListBoxObject()
+  : mListBoxBody(nullptr)
+{
+}
+
+ListBoxObject::~ListBoxObject()
+{
+}
+
+JSObject* ListBoxObject::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return ListBoxObjectBinding::Wrap(aCx, this, aGivenProto);
+}
+
+// nsIListBoxObject
+NS_IMETHODIMP
+ListBoxObject::GetRowCount(int32_t *aResult)
+{
+  *aResult = GetRowCount();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ListBoxObject::GetItemAtIndex(int32_t index, nsIDOMElement **_retval)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body) {
+    return body->GetItemAtIndex(index, _retval);
+  }
+  return NS_OK;
+ }
+
+NS_IMETHODIMP
+ListBoxObject::GetIndexOfItem(nsIDOMElement* aElement, int32_t *aResult)
+{
+  *aResult = 0;
+
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body) {
+    return body->GetIndexOfItem(aElement, aResult);
+  }
+  return NS_OK;
+}
+
+// ListBoxObject
+
+int32_t
+ListBoxObject::GetRowCount()
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body) {
+    return body->GetRowCount();
+  }
+  return 0;
+}
+
+int32_t
+ListBoxObject::GetNumberOfVisibleRows()
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body) {
+    return body->GetNumberOfVisibleRows();
+  }
+  return 0;
+}
+
+int32_t
+ListBoxObject::GetIndexOfFirstVisibleRow()
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body) {
+    return body->GetIndexOfFirstVisibleRow();
+  }
+  return 0;
+}
+
+void
+ListBoxObject::EnsureIndexIsVisible(int32_t aRowIndex)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body) {
+    body->EnsureIndexIsVisible(aRowIndex);
+  }
+}
+
+void
+ListBoxObject::ScrollToIndex(int32_t aRowIndex)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body) {
+    body->ScrollToIndex(aRowIndex);
+  }
+}
+
+void
+ListBoxObject::ScrollByLines(int32_t aNumLines)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body) {
+    body->ScrollByLines(aNumLines);
+  }
+}
+
+already_AddRefed<Element>
+ListBoxObject::GetItemAtIndex(int32_t index)
+{
+  nsCOMPtr<nsIDOMElement> el;
+  GetItemAtIndex(index, getter_AddRefs(el));
+  nsCOMPtr<Element> ret(do_QueryInterface(el));
+  return ret.forget();
+}
+
+int32_t
+ListBoxObject::GetIndexOfItem(Element& aElement)
+{
+  int32_t ret;
+  nsCOMPtr<nsIDOMElement> el(do_QueryInterface(&aElement));
+  GetIndexOfItem(el, &ret);
+  return ret;
+}
+
+//////////////////////
+
+static nsIContent*
+FindBodyContent(nsIContent* aParent)
+{
+  if (aParent->IsXULElement(nsGkAtoms::listboxbody)) {
+    return aParent;
+  }
+
+  mozilla::dom::FlattenedChildIterator iter(aParent);
+  for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+    nsIContent* result = FindBodyContent(child);
+    if (result) {
+      return result;
+    }
+  }
+
+  return nullptr;
+}
+
+nsListBoxBodyFrame*
+ListBoxObject::GetListBoxBody(bool aFlush)
+{
+  if (mListBoxBody) {
+    return mListBoxBody;
+  }
+
+  nsIPresShell* shell = GetPresShell(false);
+  if (!shell) {
+    return nullptr;
+  }
+
+  nsIFrame* frame = aFlush ?
+                      GetFrame(false) /* does Flush_Frames */ :
+                      mContent->GetPrimaryFrame();
+  if (!frame) {
+    return nullptr;
+  }
+
+  // Iterate over our content model children looking for the body.
+  nsCOMPtr<nsIContent> content = FindBodyContent(frame->GetContent());
+
+  if (!content) {
+    return nullptr;
+  }
+
+  // this frame will be a nsGFXScrollFrame
+  frame = content->GetPrimaryFrame();
+  if (!frame) {
+     return nullptr;
+  }
+
+  nsIScrollableFrame* scrollFrame = do_QueryFrame(frame);
+  if (!scrollFrame) {
+    return nullptr;
+  }
+
+  // this frame will be the one we want
+  nsIFrame* yeahBaby = scrollFrame->GetScrolledFrame();
+  if (!yeahBaby) {
+     return nullptr;
+  }
+
+  // It's a frame. Refcounts are irrelevant.
+  nsListBoxBodyFrame* listBoxBody = do_QueryFrame(yeahBaby);
+  NS_ENSURE_TRUE(listBoxBody &&
+                 listBoxBody->SetBoxObject(this),
+                 nullptr);
+  mListBoxBody = listBoxBody;
+  return mListBoxBody;
+}
+
+void
+ListBoxObject::Clear()
+{
+  ClearCachedValues();
+  BoxObject::Clear();
+}
+
+void
+ListBoxObject::ClearCachedValues()
+{
+  mListBoxBody = nullptr;
+}
+
+} // namespace dom
+} // namespace mozilla
+
+// Creation Routine ///////////////////////////////////////////////////////////////////////
+
+nsresult
+NS_NewListBoxObject(nsIBoxObject** aResult)
+{
+  NS_ADDREF(*aResult = new mozilla::dom::ListBoxObject());
+  return NS_OK;
+}
diff --git a/layout/xul/ListBoxObject.h b/layout/xul/ListBoxObject.h
new file mode 100644
index 0000000000..39cdf5c8c1
--- /dev/null
+++ b/layout/xul/ListBoxObject.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ListBoxObject_h
+#define mozilla_dom_ListBoxObject_h
+
+#include "mozilla/dom/BoxObject.h"
+#include "nsPIListBoxObject.h"
+
+namespace mozilla {
+namespace dom {
+
+class ListBoxObject final : public BoxObject,
+                            public nsPIListBoxObject
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSILISTBOXOBJECT
+
+  ListBoxObject();
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+
+  // nsPIListBoxObject
+  virtual nsListBoxBodyFrame* GetListBoxBody(bool aFlush) override;
+
+  // nsPIBoxObject
+  virtual void Clear() override;
+  virtual void ClearCachedValues() override;
+
+  // ListBoxObject.webidl
+  int32_t GetRowCount();
+  int32_t GetNumberOfVisibleRows();
+  int32_t GetIndexOfFirstVisibleRow();
+  void EnsureIndexIsVisible(int32_t rowIndex);
+  void ScrollToIndex(int32_t rowIndex);
+  void ScrollByLines(int32_t numLines);
+  already_AddRefed<Element> GetItemAtIndex(int32_t index);
+  int32_t GetIndexOfItem(Element& item);
+
+protected:
+  nsListBoxBodyFrame *mListBoxBody;
+
+private:
+  ~ListBoxObject();
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_ListBoxObject_h
diff --git a/layout/xul/MenuBoxObject.cpp b/layout/xul/MenuBoxObject.cpp
new file mode 100644
index 0000000000..ab105fd176
--- /dev/null
+++ b/layout/xul/MenuBoxObject.cpp
@@ -0,0 +1,151 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/MenuBoxObject.h"
+#include "mozilla/dom/MenuBoxObjectBinding.h"
+
+#include "mozilla/dom/KeyboardEvent.h"
+#include "mozilla/dom/Element.h"
+#include "nsIDOMKeyEvent.h"
+#include "nsIFrame.h"
+#include "nsMenuBarFrame.h"
+#include "nsMenuBarListener.h"
+#include "nsMenuFrame.h"
+#include "nsMenuPopupFrame.h"
+
+namespace mozilla {
+namespace dom {
+
+MenuBoxObject::MenuBoxObject()
+{
+}
+
+MenuBoxObject::~MenuBoxObject()
+{
+}
+
+JSObject* MenuBoxObject::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return MenuBoxObjectBinding::Wrap(aCx, this, aGivenProto);
+}
+
+void MenuBoxObject::OpenMenu(bool aOpenFlag)
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm) {
+    nsIFrame* frame = GetFrame(false);
+    if (frame) {
+      if (aOpenFlag) {
+        nsCOMPtr<nsIContent> content = mContent;
+        pm->ShowMenu(content, false, false);
+      }
+      else {
+        nsMenuFrame* menu = do_QueryFrame(frame);
+        if (menu) {
+          nsMenuPopupFrame* popupFrame = menu->GetPopup();
+          if (popupFrame)
+            pm->HidePopup(popupFrame->GetContent(), false, true, false, false);
+        }
+      }
+    }
+  }
+}
+
+already_AddRefed<Element>
+MenuBoxObject::GetActiveChild()
+{
+  nsMenuFrame* menu = do_QueryFrame(GetFrame(false));
+  if (menu) {
+    nsCOMPtr<nsIDOMElement> el;
+    menu->GetActiveChild(getter_AddRefs(el));
+    nsCOMPtr<Element> ret(do_QueryInterface(el));
+    return ret.forget();
+  }
+  return nullptr;
+}
+
+void MenuBoxObject::SetActiveChild(Element* arg)
+{
+  nsMenuFrame* menu = do_QueryFrame(GetFrame(false));
+  if (menu) {
+    nsCOMPtr<nsIDOMElement> el(do_QueryInterface(arg));
+    menu->SetActiveChild(el);
+  }
+}
+
+bool MenuBoxObject::HandleKeyPress(KeyboardEvent& keyEvent)
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (!pm) {
+    return false;
+  }
+
+  // if event has already been handled, bail
+  bool eventHandled = false;
+  keyEvent.GetDefaultPrevented(&eventHandled);
+  if (eventHandled) {
+    return false;
+  }
+
+  if (nsMenuBarListener::IsAccessKeyPressed(&keyEvent))
+    return false;
+
+  nsMenuFrame* menu = do_QueryFrame(GetFrame(false));
+  if (!menu) {
+    return false;
+  }
+
+  nsMenuPopupFrame* popupFrame = menu->GetPopup();
+  if (!popupFrame) {
+    return false;
+  }
+
+  uint32_t keyCode = keyEvent.KeyCode();
+  switch (keyCode) {
+    case nsIDOMKeyEvent::DOM_VK_UP:
+    case nsIDOMKeyEvent::DOM_VK_DOWN:
+    case nsIDOMKeyEvent::DOM_VK_HOME:
+    case nsIDOMKeyEvent::DOM_VK_END:
+    {
+      nsNavigationDirection theDirection;
+      theDirection = NS_DIRECTION_FROM_KEY_CODE(popupFrame, keyCode);
+      return pm->HandleKeyboardNavigationInPopup(popupFrame, theDirection);
+    }
+    default:
+      return pm->HandleShortcutNavigation(&keyEvent, popupFrame);
+  }
+}
+
+bool MenuBoxObject::OpenedWithKey()
+{
+  nsMenuFrame* menuframe = do_QueryFrame(GetFrame(false));
+  if (!menuframe) {
+    return false;
+  }
+
+  nsIFrame* frame = menuframe->GetParent();
+  while (frame) {
+    nsMenuBarFrame* menubar = do_QueryFrame(frame);
+    if (menubar) {
+      return menubar->IsActiveByKeyboard();
+    }
+    frame = frame->GetParent();
+  }
+  return false;
+}
+
+} // namespace dom
+} // namespace mozilla
+
+// Creation Routine ///////////////////////////////////////////////////////////////////////
+
+using namespace mozilla::dom;
+
+nsresult
+NS_NewMenuBoxObject(nsIBoxObject** aResult)
+{
+  NS_ADDREF(*aResult = new MenuBoxObject());
+  return NS_OK;
+}
diff --git a/layout/xul/MenuBoxObject.h b/layout/xul/MenuBoxObject.h
new file mode 100644
index 0000000000..652e3231fa
--- /dev/null
+++ b/layout/xul/MenuBoxObject.h
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_MenuBoxObject_h
+#define mozilla_dom_MenuBoxObject_h
+
+#include "mozilla/dom/BoxObject.h"
+
+namespace mozilla {
+namespace dom {
+
+class KeyboardEvent;
+
+class MenuBoxObject final : public BoxObject
+{
+public:
+
+  MenuBoxObject();
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+
+  void OpenMenu(bool aOpenFlag);
+  already_AddRefed<Element> GetActiveChild();
+  void SetActiveChild(Element* arg);
+  bool HandleKeyPress(KeyboardEvent& keyEvent);
+  bool OpenedWithKey();
+
+private:
+  ~MenuBoxObject();
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_MenuBoxObject_h
diff --git a/layout/xul/PopupBoxObject.cpp b/layout/xul/PopupBoxObject.cpp
new file mode 100644
index 0000000000..00ecc943d8
--- /dev/null
+++ b/layout/xul/PopupBoxObject.cpp
@@ -0,0 +1,384 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMPtr.h"
+#include "nsIRootBox.h"
+#include "nsIPresShell.h"
+#include "nsIContent.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsMenuPopupFrame.h"
+#include "nsView.h"
+#include "mozilla/AppUnits.h"
+#include "mozilla/dom/DOMRect.h"
+#include "mozilla/dom/PopupBoxObject.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/dom/PopupBoxObjectBinding.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_ADDREF_INHERITED(PopupBoxObject, BoxObject)
+NS_IMPL_RELEASE_INHERITED(PopupBoxObject, BoxObject)
+NS_INTERFACE_MAP_BEGIN(PopupBoxObject)
+NS_INTERFACE_MAP_END_INHERITING(BoxObject)
+
+PopupBoxObject::PopupBoxObject()
+{
+}
+
+PopupBoxObject::~PopupBoxObject()
+{
+}
+
+nsIContent* PopupBoxObject::GetParentObject() const
+{
+  return BoxObject::GetParentObject();
+}
+
+JSObject* PopupBoxObject::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return PopupBoxObjectBinding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPopupSetFrame*
+PopupBoxObject::GetPopupSetFrame()
+{
+  nsIRootBox* rootBox = nsIRootBox::GetRootBox(GetPresShell(false));
+  if (!rootBox)
+    return nullptr;
+
+  return rootBox->GetPopupSetFrame();
+}
+
+void
+PopupBoxObject::HidePopup(bool aCancel)
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm && mContent) {
+    pm->HidePopup(mContent, false, true, false, aCancel);
+  }
+}
+
+void
+PopupBoxObject::ShowPopup(Element* aAnchorElement,
+                          Element& aPopupElement,
+                          int32_t aXPos, int32_t aYPos,
+                          const nsAString& aPopupType,
+                          const nsAString& aAnchorAlignment,
+                          const nsAString& aPopupAlignment)
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm && mContent) {
+    nsCOMPtr<nsIContent> anchorContent(do_QueryInterface(aAnchorElement));
+    nsAutoString popupType(aPopupType);
+    nsAutoString anchor(aAnchorAlignment);
+    nsAutoString align(aPopupAlignment);
+    pm->ShowPopupWithAnchorAlign(mContent, anchorContent, anchor, align,
+                                 aXPos, aYPos,
+                                 popupType.EqualsLiteral("context"));
+  }
+}
+
+void
+PopupBoxObject::OpenPopup(Element* aAnchorElement,
+                          const nsAString& aPosition,
+                          int32_t aXPos, int32_t aYPos,
+                          bool aIsContextMenu,
+                          bool aAttributesOverride,
+                          Event* aTriggerEvent)
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm && mContent) {
+    nsCOMPtr<nsIContent> anchorContent(do_QueryInterface(aAnchorElement));
+    pm->ShowPopup(mContent, anchorContent, aPosition, aXPos, aYPos,
+                  aIsContextMenu, aAttributesOverride, false, aTriggerEvent);
+  }
+}
+
+void
+PopupBoxObject::OpenPopupAtScreen(int32_t aXPos, int32_t aYPos,
+                                  bool aIsContextMenu,
+                                  Event* aTriggerEvent)
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm && mContent)
+    pm->ShowPopupAtScreen(mContent, aXPos, aYPos, aIsContextMenu, aTriggerEvent);
+}
+
+void
+PopupBoxObject::OpenPopupAtScreenRect(const nsAString& aPosition,
+                                      int32_t aXPos, int32_t aYPos,
+                                      int32_t aWidth, int32_t aHeight,
+                                      bool aIsContextMenu,
+                                      bool aAttributesOverride,
+                                      Event* aTriggerEvent)
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm && mContent) {
+    pm->ShowPopupAtScreenRect(mContent, aPosition,
+                              nsIntRect(aXPos, aYPos, aWidth, aHeight),
+                              aIsContextMenu, aAttributesOverride, aTriggerEvent);
+  }
+}
+
+void
+PopupBoxObject::MoveTo(int32_t aLeft, int32_t aTop)
+{
+  nsMenuPopupFrame *menuPopupFrame = mContent ? do_QueryFrame(mContent->GetPrimaryFrame()) : nullptr;
+  if (menuPopupFrame) {
+    menuPopupFrame->MoveTo(CSSIntPoint(aLeft, aTop), true);
+  }
+}
+
+void
+PopupBoxObject::MoveToAnchor(Element* aAnchorElement,
+                             const nsAString& aPosition,
+                             int32_t aXPos, int32_t aYPos,
+                             bool aAttributesOverride)
+{
+  if (mContent) {
+    nsCOMPtr<nsIContent> anchorContent(do_QueryInterface(aAnchorElement));
+
+    nsMenuPopupFrame *menuPopupFrame = do_QueryFrame(mContent->GetPrimaryFrame());
+    if (menuPopupFrame && menuPopupFrame->IsVisible()) {
+      menuPopupFrame->MoveToAnchor(anchorContent, aPosition, aXPos, aYPos, aAttributesOverride);
+    }
+  }
+}
+
+void
+PopupBoxObject::SizeTo(int32_t aWidth, int32_t aHeight)
+{
+  if (!mContent)
+    return;
+
+  nsAutoString width, height;
+  width.AppendInt(aWidth);
+  height.AppendInt(aHeight);
+
+  nsCOMPtr<nsIContent> content = mContent;
+
+  // We only want to pass aNotify=true to SetAttr once, but must make sure
+  // we pass it when a value is being changed.  Thus, we check if the height
+  // is the same and if so, pass true when setting the width.
+  bool heightSame = content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::height, height, eCaseMatters);
+
+  content->SetAttr(kNameSpaceID_None, nsGkAtoms::width, width, heightSame);
+  content->SetAttr(kNameSpaceID_None, nsGkAtoms::height, height, true);
+}
+
+bool
+PopupBoxObject::AutoPosition()
+{
+  nsMenuPopupFrame *menuPopupFrame = mContent ? do_QueryFrame(mContent->GetPrimaryFrame()) : nullptr;
+  if (menuPopupFrame) {
+    return menuPopupFrame->GetAutoPosition();
+  }
+  return true;
+}
+
+void
+PopupBoxObject::SetAutoPosition(bool aShouldAutoPosition)
+{
+  nsMenuPopupFrame *menuPopupFrame = mContent ? do_QueryFrame(mContent->GetPrimaryFrame()) : nullptr;
+  if (menuPopupFrame) {
+    menuPopupFrame->SetAutoPosition(aShouldAutoPosition);
+  }
+}
+
+void
+PopupBoxObject::EnableRollup(bool aShouldRollup)
+{
+  // this does nothing now
+}
+
+void
+PopupBoxObject::SetConsumeRollupEvent(uint32_t aConsume)
+{
+  nsMenuPopupFrame *menuPopupFrame = do_QueryFrame(GetFrame(false));
+  if (menuPopupFrame) {
+    menuPopupFrame->SetConsumeRollupEvent(aConsume);
+  }
+}
+
+void
+PopupBoxObject::EnableKeyboardNavigator(bool aEnableKeyboardNavigator)
+{
+  if (!mContent)
+    return;
+
+  // Use ignorekeys="true" on the popup instead of using this function.
+  if (aEnableKeyboardNavigator)
+    mContent->UnsetAttr(kNameSpaceID_None, nsGkAtoms::ignorekeys, true);
+  else
+    mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::ignorekeys,
+                      NS_LITERAL_STRING("true"), true);
+}
+
+void
+PopupBoxObject::GetPopupState(nsString& aState)
+{
+  // set this here in case there's no frame for the popup
+  aState.AssignLiteral("closed");
+
+  nsMenuPopupFrame *menuPopupFrame = mContent ? do_QueryFrame(mContent->GetPrimaryFrame()) : nullptr;
+  if (menuPopupFrame) {
+    switch (menuPopupFrame->PopupState()) {
+      case ePopupShown:
+        aState.AssignLiteral("open");
+        break;
+      case ePopupShowing:
+      case ePopupPositioning:
+      case ePopupOpening:
+      case ePopupVisible:
+        aState.AssignLiteral("showing");
+        break;
+      case ePopupHiding:
+      case ePopupInvisible:
+        aState.AssignLiteral("hiding");
+        break;
+      case ePopupClosed:
+        break;
+      default:
+        NS_NOTREACHED("Bad popup state");
+        break;
+    }
+  }
+}
+
+nsINode*
+PopupBoxObject::GetTriggerNode() const
+{
+  nsMenuPopupFrame *menuPopupFrame = mContent ? do_QueryFrame(mContent->GetPrimaryFrame()) : nullptr;
+  return nsMenuPopupFrame::GetTriggerContent(menuPopupFrame);
+}
+
+Element*
+PopupBoxObject::GetAnchorNode() const
+{
+  nsMenuPopupFrame *menuPopupFrame = mContent ? do_QueryFrame(mContent->GetPrimaryFrame()) : nullptr;
+  if (!menuPopupFrame) {
+    return nullptr;
+  }
+
+  nsIContent* anchor = menuPopupFrame->GetAnchor();
+  return anchor && anchor->IsElement() ? anchor->AsElement() : nullptr;
+}
+
+already_AddRefed<DOMRect>
+PopupBoxObject::GetOuterScreenRect()
+{
+  RefPtr<DOMRect> rect = new DOMRect(mContent);
+
+  // Return an empty rectangle if the popup is not open.
+  nsMenuPopupFrame *menuPopupFrame = do_QueryFrame(GetFrame(false));
+  if (!menuPopupFrame || !menuPopupFrame->IsOpen()) {
+    return rect.forget();
+  }
+
+  nsView* view = menuPopupFrame->GetView();
+  if (view) {
+    nsIWidget* widget = view->GetWidget();
+    if (widget) {
+      LayoutDeviceIntRect screenRect = widget->GetScreenBounds();
+
+      int32_t pp = menuPopupFrame->PresContext()->AppUnitsPerDevPixel();
+      rect->SetLayoutRect(LayoutDeviceIntRect::ToAppUnits(screenRect, pp));
+    }
+  }
+  return rect.forget();
+}
+
+void
+PopupBoxObject::GetAlignmentPosition(nsString& positionStr)
+{
+  positionStr.Truncate();
+
+  // This needs to flush layout.
+  nsMenuPopupFrame *menuPopupFrame = do_QueryFrame(GetFrame(true));
+  if (!menuPopupFrame)
+    return;
+
+  int8_t position = menuPopupFrame->GetAlignmentPosition();
+  switch (position) {
+    case POPUPPOSITION_AFTERSTART:
+      positionStr.AssignLiteral("after_start");
+      break;
+    case POPUPPOSITION_AFTEREND:
+      positionStr.AssignLiteral("after_end");
+      break;
+    case POPUPPOSITION_BEFORESTART:
+      positionStr.AssignLiteral("before_start");
+      break;
+    case POPUPPOSITION_BEFOREEND:
+      positionStr.AssignLiteral("before_end");
+      break;
+    case POPUPPOSITION_STARTBEFORE:
+      positionStr.AssignLiteral("start_before");
+      break;
+    case POPUPPOSITION_ENDBEFORE:
+      positionStr.AssignLiteral("end_before");
+      break;
+    case POPUPPOSITION_STARTAFTER:
+      positionStr.AssignLiteral("start_after");
+      break;
+    case POPUPPOSITION_ENDAFTER:
+      positionStr.AssignLiteral("end_after");
+      break;
+    case POPUPPOSITION_OVERLAP:
+      positionStr.AssignLiteral("overlap");
+      break;
+    case POPUPPOSITION_AFTERPOINTER:
+      positionStr.AssignLiteral("after_pointer");
+      break;
+    case POPUPPOSITION_SELECTION:
+      positionStr.AssignLiteral("selection");
+      break;
+    default:
+      // Leave as an empty string.
+      break;
+  }
+}
+
+int32_t
+PopupBoxObject::AlignmentOffset()
+{
+  nsMenuPopupFrame *menuPopupFrame = do_QueryFrame(GetFrame(false));
+  if (!menuPopupFrame)
+    return 0;
+
+  int32_t pp = mozilla::AppUnitsPerCSSPixel();
+  // Note that the offset might be along either the X or Y axis, but for the
+  // sake of simplicity we use a point with only the X axis set so we can
+  // use ToNearestPixels().
+  nsPoint appOffset(menuPopupFrame->GetAlignmentOffset(), 0);
+  nsIntPoint popupOffset = appOffset.ToNearestPixels(pp);
+  return popupOffset.x;
+}
+
+void
+PopupBoxObject::SetConstraintRect(dom::DOMRectReadOnly& aRect)
+{
+  nsMenuPopupFrame *menuPopupFrame = do_QueryFrame(GetFrame(false));
+  if (menuPopupFrame) {
+    menuPopupFrame->SetOverrideConstraintRect(
+      LayoutDeviceIntRect::Truncate(aRect.Left(), aRect.Top(), aRect.Width(), aRect.Height()));
+  }
+}
+
+} // namespace dom
+} // namespace mozilla
+
+// Creation Routine ///////////////////////////////////////////////////////////////////////
+
+nsresult
+NS_NewPopupBoxObject(nsIBoxObject** aResult)
+{
+  *aResult = new mozilla::dom::PopupBoxObject();
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
diff --git a/layout/xul/PopupBoxObject.h b/layout/xul/PopupBoxObject.h
new file mode 100644
index 0000000000..a660393b58
--- /dev/null
+++ b/layout/xul/PopupBoxObject.h
@@ -0,0 +1,115 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_PopupBoxObject_h
+#define mozilla_dom_PopupBoxObject_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/ErrorResult.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsWrapperCache.h"
+#include "mozilla/dom/BoxObject.h"
+#include "nsString.h"
+
+struct JSContext;
+class nsPopupSetFrame;
+
+namespace mozilla {
+namespace dom {
+
+class DOMRect;
+class Element;
+class Event;
+
+class PopupBoxObject final : public BoxObject
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  // also in PopupBoxObject.webidl
+  static const uint32_t ROLLUP_DEFAULT = 0;   /* widget/platform default */
+  static const uint32_t ROLLUP_CONSUME = 1;   /* consume the rollup event */
+  static const uint32_t ROLLUP_NO_CONSUME = 2; /* don't consume the rollup event */
+
+  PopupBoxObject();
+
+  nsIContent* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+
+  void ShowPopup(Element* aAnchorElement,
+                 Element& aPopupElement,
+                 int32_t aXPos,
+                 int32_t aYPos,
+                 const nsAString& aPopupType,
+                 const nsAString& aAnchorAlignment,
+                 const nsAString& aPopupAlignment);
+
+  void HidePopup(bool aCancel);
+
+  bool AutoPosition();
+
+  void SetAutoPosition(bool aShouldAutoPosition);
+
+  void EnableKeyboardNavigator(bool aEnableKeyboardNavigator);
+
+  void EnableRollup(bool aShouldRollup);
+
+  void SetConsumeRollupEvent(uint32_t aConsume);
+
+  void SizeTo(int32_t aWidth, int32_t aHeight);
+
+  void MoveTo(int32_t aLeft, int32_t aTop);
+
+  void OpenPopup(Element* aAnchorElement,
+                 const nsAString& aPosition,
+                 int32_t aXPos,
+                 int32_t aYPos,
+                 bool aIsContextMenu, bool aAttributesOverride,
+                 Event* aTriggerEvent);
+
+  void OpenPopupAtScreen(int32_t aXPos,
+                         int32_t aYPos,
+                         bool aIsContextMenu,
+                         Event* aTriggerEvent);
+
+  void OpenPopupAtScreenRect(const nsAString& aPosition,
+                             int32_t aXPos, int32_t aYPos,
+                             int32_t aWidth, int32_t aHeight,
+                             bool aIsContextMenu,
+                             bool aAttributesOverride,
+                             Event* aTriggerEvent);
+
+  void GetPopupState(nsString& aState);
+
+  nsINode* GetTriggerNode() const;
+
+  Element* GetAnchorNode() const;
+
+  already_AddRefed<DOMRect> GetOuterScreenRect();
+
+  void MoveToAnchor(Element* aAnchorElement,
+                    const nsAString& aPosition,
+                    int32_t aXPos,
+                    int32_t aYPos,
+                    bool aAttributesOverride);
+
+  void GetAlignmentPosition(nsString& positionStr);
+
+  int32_t AlignmentOffset();
+
+  void SetConstraintRect(dom::DOMRectReadOnly& aRect);
+
+private:
+  ~PopupBoxObject();
+
+protected:
+  nsPopupSetFrame* GetPopupSetFrame();
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_PopupBoxObject_h
diff --git a/layout/xul/ScrollBoxObject.cpp b/layout/xul/ScrollBoxObject.cpp
new file mode 100644
index 0000000000..26f7bc9bb1
--- /dev/null
+++ b/layout/xul/ScrollBoxObject.cpp
@@ -0,0 +1,384 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/ScrollBoxObject.h"
+#include "mozilla/dom/ScrollBoxObjectBinding.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/ToJSValue.h"
+#include "nsCOMPtr.h"
+#include "nsIPresShell.h"
+#include "nsIContent.h"
+#include "nsIDOMElement.h"
+#include "nsPresContext.h"
+#include "nsBox.h"
+#include "nsIScrollableFrame.h"
+
+namespace mozilla {
+namespace dom {
+
+ScrollBoxObject::ScrollBoxObject()
+{
+}
+
+ScrollBoxObject::~ScrollBoxObject()
+{
+}
+
+JSObject* ScrollBoxObject::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return ScrollBoxObjectBinding::Wrap(aCx, this, aGivenProto);
+}
+
+nsIScrollableFrame* ScrollBoxObject::GetScrollFrame()
+{
+  return do_QueryFrame(GetFrame(false));
+}
+
+void ScrollBoxObject::ScrollTo(int32_t x, int32_t y, ErrorResult& aRv)
+{
+  nsIScrollableFrame* sf = GetScrollFrame();
+  if (!sf) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  sf->ScrollToCSSPixels(CSSIntPoint(x, y));
+}
+
+void ScrollBoxObject::ScrollBy(int32_t dx, int32_t dy, ErrorResult& aRv)
+{
+  CSSIntPoint pt;
+  GetPosition(pt, aRv);
+
+  if (aRv.Failed()) {
+    return;
+  }
+
+  ScrollTo(pt.x + dx, pt.y + dy, aRv);
+}
+
+void ScrollBoxObject::ScrollByLine(int32_t dlines, ErrorResult& aRv)
+{
+  nsIScrollableFrame* sf = GetScrollFrame();
+  if (!sf) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  sf->ScrollBy(nsIntPoint(0, dlines), nsIScrollableFrame::LINES,
+               nsIScrollableFrame::SMOOTH);
+}
+
+// XUL <scrollbox> elements have a single box child element.
+// Get a pointer to that box.
+// Note that now that the <scrollbox> is just a regular box
+// with 'overflow:hidden', the boxobject's frame is an nsXULScrollFrame,
+// the <scrollbox>'s box frame is the scrollframe's "scrolled frame", and
+// the <scrollbox>'s child box is a child of that.
+static nsIFrame* GetScrolledBox(BoxObject* aScrollBox) {
+  nsIFrame* frame = aScrollBox->GetFrame(false);
+  if (!frame) {
+    return nullptr;
+  }
+
+  nsIScrollableFrame* scrollFrame = do_QueryFrame(frame);
+  if (!scrollFrame) {
+    NS_WARNING("ScrollBoxObject attached to something that's not a scroll frame!");
+    return nullptr;
+  }
+
+  nsIFrame* scrolledFrame = scrollFrame->GetScrolledFrame();
+  if (!scrolledFrame)
+    return nullptr;
+  return nsBox::GetChildXULBox(scrolledFrame);
+}
+
+void ScrollBoxObject::ScrollByIndex(int32_t dindexes, ErrorResult& aRv)
+{
+    nsIScrollableFrame* sf = GetScrollFrame();
+    if (!sf) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return;
+    }
+
+    nsIFrame* scrolledBox = GetScrolledBox(this);
+    if (!scrolledBox) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return;
+    }
+
+    nsRect rect;
+
+    // now get the scrolled boxes first child.
+    nsIFrame* child = nsBox::GetChildXULBox(scrolledBox);
+
+    bool horiz = scrolledBox->IsXULHorizontal();
+    nsPoint cp = sf->GetScrollPosition();
+    nscoord diff = 0;
+    int32_t curIndex = 0;
+    bool isLTR = scrolledBox->IsXULNormalDirection();
+
+    int32_t frameWidth = 0;
+    if (!isLTR && horiz) {
+      GetWidth(&frameWidth);
+      nsCOMPtr<nsIPresShell> shell = GetPresShell(false);
+      if (!shell) {
+        aRv.Throw(NS_ERROR_UNEXPECTED);
+        return;
+      }
+      frameWidth = nsPresContext::CSSPixelsToAppUnits(frameWidth);
+    }
+
+    // first find out what index we are currently at
+    while(child) {
+      rect = child->GetRect();
+      if (horiz) {
+        // In the left-to-right case we break from the loop when the center of
+        // the current child rect is greater than the scrolled position of
+        // the left edge of the scrollbox
+        // In the right-to-left case we break when the center of the current
+        // child rect is less than the scrolled position of the right edge of
+        // the scrollbox.
+        diff = rect.x + rect.width/2; // use the center, to avoid rounding errors
+        if ((isLTR && diff > cp.x) ||
+            (!isLTR && diff < cp.x + frameWidth)) {
+          break;
+        }
+      } else {
+        diff = rect.y + rect.height/2;// use the center, to avoid rounding errors
+        if (diff > cp.y) {
+          break;
+        }
+      }
+      child = nsBox::GetNextXULBox(child);
+      curIndex++;
+    }
+
+    int32_t count = 0;
+
+    if (dindexes == 0)
+      return;
+
+    if (dindexes > 0) {
+      while(child) {
+        child = nsBox::GetNextXULBox(child);
+        if (child) {
+          rect = child->GetRect();
+        }
+        count++;
+        if (count >= dindexes) {
+          break;
+        }
+      }
+
+   } else if (dindexes < 0) {
+      child = nsBox::GetChildXULBox(scrolledBox);
+      while(child) {
+        rect = child->GetRect();
+        if (count >= curIndex + dindexes) {
+          break;
+        }
+
+        count++;
+        child = nsBox::GetNextXULBox(child);
+
+      }
+   }
+
+   nscoord csspixel = nsPresContext::CSSPixelsToAppUnits(1);
+   if (horiz) {
+       // In the left-to-right case we scroll so that the left edge of the
+       // selected child is scrolled to the left edge of the scrollbox.
+       // In the right-to-left case we scroll so that the right edge of the
+       // selected child is scrolled to the right edge of the scrollbox.
+
+       nsPoint pt(isLTR ? rect.x : rect.x + rect.width - frameWidth,
+                  cp.y);
+
+       // Use a destination range that ensures the left edge (or right edge,
+       // for RTL) will indeed be visible. Also ensure that the top edge
+       // is visible.
+       nsRect range(pt.x, pt.y, csspixel, 0);
+       if (isLTR) {
+         range.x -= csspixel;
+       }
+       sf->ScrollTo(pt, nsIScrollableFrame::INSTANT, &range);
+   } else {
+       // Use a destination range that ensures the top edge will be visible.
+       nsRect range(cp.x, rect.y - csspixel, 0, csspixel);
+       sf->ScrollTo(nsPoint(cp.x, rect.y), nsIScrollableFrame::INSTANT, &range);
+   }
+}
+
+void ScrollBoxObject::ScrollToLine(int32_t line, ErrorResult& aRv)
+{
+  nsIScrollableFrame* sf = GetScrollFrame();
+  if (!sf) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  nscoord y = sf->GetLineScrollAmount().height * line;
+  nsRect range(0, y - nsPresContext::CSSPixelsToAppUnits(1),
+               0, nsPresContext::CSSPixelsToAppUnits(1));
+  sf->ScrollTo(nsPoint(0, y), nsIScrollableFrame::INSTANT, &range);
+}
+
+void ScrollBoxObject::ScrollToElement(Element& child, ErrorResult& aRv)
+{
+  nsCOMPtr<nsIPresShell> shell = GetPresShell(false);
+  if (!shell) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return;
+  }
+
+  shell->ScrollContentIntoView(&child,
+                               nsIPresShell::ScrollAxis(
+                                 nsIPresShell::SCROLL_TOP,
+                                 nsIPresShell::SCROLL_ALWAYS),
+                               nsIPresShell::ScrollAxis(
+                                 nsIPresShell::SCROLL_LEFT,
+                                 nsIPresShell::SCROLL_ALWAYS),
+                               nsIPresShell::SCROLL_FIRST_ANCESTOR_ONLY |
+                               nsIPresShell::SCROLL_OVERFLOW_HIDDEN);
+}
+
+void ScrollBoxObject::ScrollToIndex(int32_t index, ErrorResult& aRv)
+{
+  aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
+}
+
+int32_t ScrollBoxObject::GetPositionX(ErrorResult& aRv)
+{
+  CSSIntPoint pt;
+  GetPosition(pt, aRv);
+  return pt.x;
+}
+
+int32_t ScrollBoxObject::GetPositionY(ErrorResult& aRv)
+{
+  CSSIntPoint pt;
+  GetPosition(pt, aRv);
+  return pt.y;
+}
+
+int32_t ScrollBoxObject::GetScrolledWidth(ErrorResult& aRv)
+{
+  nsRect scrollRect;
+  GetScrolledSize(scrollRect, aRv);
+  return scrollRect.width;
+}
+
+int32_t ScrollBoxObject::GetScrolledHeight(ErrorResult& aRv)
+{
+  nsRect scrollRect;
+  GetScrolledSize(scrollRect, aRv);
+  return scrollRect.height;
+}
+
+/* private helper */
+void ScrollBoxObject::GetPosition(CSSIntPoint& aPos, ErrorResult& aRv)
+{
+  nsIScrollableFrame* sf = GetScrollFrame();
+  if (!sf) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  aPos = sf->GetScrollPositionCSSPixels();
+}
+
+/* private helper */
+void ScrollBoxObject::GetScrolledSize(nsRect& aRect, ErrorResult& aRv)
+{
+    nsIFrame* scrolledBox = GetScrolledBox(this);
+    if (!scrolledBox) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return;
+    }
+
+    aRect = scrolledBox->GetRect();
+    aRect.width  = nsPresContext::AppUnitsToIntCSSPixels(aRect.width);
+    aRect.height = nsPresContext::AppUnitsToIntCSSPixels(aRect.height);
+}
+
+void ScrollBoxObject::GetPosition(JSContext* cx,
+                                  JS::Handle<JSObject*> x,
+                                  JS::Handle<JSObject*> y,
+                                  ErrorResult& aRv)
+{
+  CSSIntPoint pt;
+  GetPosition(pt, aRv);
+  JS::Rooted<JS::Value> v(cx);
+  if (!ToJSValue(cx, pt.x, &v) ||
+      !JS_SetProperty(cx, x, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+  if (!ToJSValue(cx, pt.y, &v) ||
+      !JS_SetProperty(cx, y, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+}
+
+void ScrollBoxObject::GetScrolledSize(JSContext* cx,
+                                      JS::Handle<JSObject*> width,
+                                      JS::Handle<JSObject*> height,
+                                      ErrorResult& aRv)
+{
+  nsRect rect;
+  GetScrolledSize(rect, aRv);
+  JS::Rooted<JS::Value> v(cx);
+  if (!ToJSValue(cx, rect.width, &v) ||
+      !JS_SetProperty(cx, width, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+  if (!ToJSValue(cx, rect.height, &v) ||
+      !JS_SetProperty(cx, height, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+}
+
+void ScrollBoxObject::EnsureElementIsVisible(Element& child, ErrorResult& aRv)
+{
+    nsCOMPtr<nsIPresShell> shell = GetPresShell(false);
+    if (!shell) {
+      aRv.Throw(NS_ERROR_UNEXPECTED);
+      return;
+    }
+
+    shell->ScrollContentIntoView(&child,
+                                 nsIPresShell::ScrollAxis(),
+                                 nsIPresShell::ScrollAxis(),
+                                 nsIPresShell::SCROLL_FIRST_ANCESTOR_ONLY |
+                                 nsIPresShell::SCROLL_OVERFLOW_HIDDEN);
+}
+
+void ScrollBoxObject::EnsureIndexIsVisible(int32_t index, ErrorResult& aRv)
+{
+  aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
+}
+
+void ScrollBoxObject::EnsureLineIsVisible(int32_t line, ErrorResult& aRv)
+{
+  aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
+}
+
+} // namespace dom
+} // namespace mozilla
+
+// Creation Routine ///////////////////////////////////////////////////////////////////////
+
+using namespace mozilla::dom;
+
+nsresult
+NS_NewScrollBoxObject(nsIBoxObject** aResult)
+{
+  NS_ADDREF(*aResult = new ScrollBoxObject());
+  return NS_OK;
+}
diff --git a/layout/xul/ScrollBoxObject.h b/layout/xul/ScrollBoxObject.h
new file mode 100644
index 0000000000..3344bf3f0d
--- /dev/null
+++ b/layout/xul/ScrollBoxObject.h
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ScrollBoxObject_h
+#define mozilla_dom_ScrollBoxObject_h
+
+#include "mozilla/dom/BoxObject.h"
+#include "Units.h"
+
+class nsIScrollableFrame;
+struct nsRect;
+
+namespace mozilla {
+namespace dom {
+
+class ScrollBoxObject final : public BoxObject
+{
+public:
+  ScrollBoxObject();
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+
+  virtual nsIScrollableFrame* GetScrollFrame();
+
+  void ScrollTo(int32_t x, int32_t y, ErrorResult& aRv);
+  void ScrollBy(int32_t dx, int32_t dy, ErrorResult& aRv);
+  void ScrollByLine(int32_t dlines, ErrorResult& aRv);
+  void ScrollByIndex(int32_t dindexes, ErrorResult& aRv);
+  void ScrollToLine(int32_t line, ErrorResult& aRv);
+  void ScrollToElement(Element& child, ErrorResult& aRv);
+  void ScrollToIndex(int32_t index, ErrorResult& aRv);
+  int32_t GetPositionX(ErrorResult& aRv);
+  int32_t GetPositionY(ErrorResult& aRv);
+  int32_t GetScrolledWidth(ErrorResult& aRv);
+  int32_t GetScrolledHeight(ErrorResult& aRv);
+  void EnsureElementIsVisible(Element& child, ErrorResult& aRv);
+  void EnsureIndexIsVisible(int32_t index, ErrorResult& aRv);
+  void EnsureLineIsVisible(int32_t line, ErrorResult& aRv);
+
+  // Deprecated APIs from old IDL
+  void GetPosition(JSContext* cx,
+                   JS::Handle<JSObject*> x,
+                   JS::Handle<JSObject*> y,
+                   ErrorResult& aRv);
+
+  void GetScrolledSize(JSContext* cx,
+                       JS::Handle<JSObject*> width,
+                       JS::Handle<JSObject*> height,
+                       ErrorResult& aRv);
+
+protected:
+  void GetScrolledSize(nsRect& aRect, ErrorResult& aRv);
+  void GetPosition(CSSIntPoint& aPos, ErrorResult& aRv);
+
+private:
+  ~ScrollBoxObject();
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_ScrollBoxObject_h
diff --git a/layout/xul/crashtests/131008-1.xul b/layout/xul/crashtests/131008-1.xul
new file mode 100644
index 0000000000..d505f86963
--- /dev/null
+++ b/layout/xul/crashtests/131008-1.xul
@@ -0,0 +1,11 @@
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+
+<window xmlns:html="http://www.w3.org/1999/xhtml"
+	xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+	xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+	id="MainWindow"
+	title="IWindow Test">
+<div style="position:absolute">abc</div>
+
+
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/137216-1.xul b/layout/xul/crashtests/137216-1.xul
new file mode 100644
index 0000000000..a3fc043c85
--- /dev/null
+++ b/layout/xul/crashtests/137216-1.xul
@@ -0,0 +1,4 @@
+<?xml version="1.0"?>

+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

+	<iframe style="position:absolute;"/>

+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/140218-1.xml b/layout/xul/crashtests/140218-1.xml
new file mode 100644
index 0000000000..311afc2188
--- /dev/null
+++ b/layout/xul/crashtests/140218-1.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0"?>

+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

+      <treechildren style = " display: block; " />

+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/151826-1.xul b/layout/xul/crashtests/151826-1.xul
new file mode 100644
index 0000000000..1115dae720
--- /dev/null
+++ b/layout/xul/crashtests/151826-1.xul
@@ -0,0 +1,27 @@
+<?xml version="1.0"?>

+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>

+

+<window

+   title      = "Arrowscrollbox->Splitter Crash Testcase"

+   xmlns      = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"

+   xmlns:html="http://www.w3.org/1999/xhtml"

+   width      = "300"

+   height     = "200"

+   orient     = "vertical"

+>

+<vbox flex="1">

+

+<scrollbox flex="1">

+<vbox flex="1">

+<vbox id="box_1">

+<hbox><label value="Test"/></hbox>

+</vbox>

+<splitter collapse="none"/>

+<vbox id="box_2">

+<hbox><label value="Test"/></hbox>

+</vbox>

+</vbox>

+</scrollbox>

+

+</vbox>

+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/168724-1.xul b/layout/xul/crashtests/168724-1.xul
new file mode 100644
index 0000000000..8456406c2f
--- /dev/null
+++ b/layout/xul/crashtests/168724-1.xul
@@ -0,0 +1,18 @@
+<?xml version="1.0"?>

+<?xml-stylesheet href="chrome://global/skin/" type="text/css" ?>

+

+<window

+  id="nodeCreator" title="Node Creator"

+  xmlns:html="http://www.w3.org/1999/xhtml"

+  xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"

+  >

+<description context="context">Right-click here, and expect a crash.</description>

+

+<popupset id="context-set">

+<popup id="context">

+<deck selectedItem="0">

+<menuitem label="You should never see this" />

+</deck>

+</popup>

+</popupset>

+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/189814-1.xul b/layout/xul/crashtests/189814-1.xul
new file mode 100644
index 0000000000..79462348c6
--- /dev/null
+++ b/layout/xul/crashtests/189814-1.xul
@@ -0,0 +1,21 @@
+<?xml version="1.0"?>
+
+<window
+  id="sliderprint" title="Print These Sliders"
+  xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+  style="background-color: white">
+
+  <label>
+  With the Classic theme, printing causes the browser to crash. adding style="-moz-appearance: none" to the
+  thumb prevents the crash. The crash doesn't happen at all with Modern.
+  </label>
+  <spacer height="10"/>
+    <hbox>
+
+        <slider style="height: 174px; width: 24px" orient="vertical">
+            <thumb/>
+        </slider>
+
+    </hbox>
+
+</window>
diff --git a/layout/xul/crashtests/237787-1.xul b/layout/xul/crashtests/237787-1.xul
new file mode 100644
index 0000000000..96cebca9ff
--- /dev/null
+++ b/layout/xul/crashtests/237787-1.xul
@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<window	xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+	<toolbar>
+		<arrowscrollbox>
+			<menulist editable="true">
+			</menulist>
+		</arrowscrollbox>
+	</toolbar>
+</window>
diff --git a/layout/xul/crashtests/265161-1.xul b/layout/xul/crashtests/265161-1.xul
new file mode 100644
index 0000000000..75a995790f
--- /dev/null
+++ b/layout/xul/crashtests/265161-1.xul
@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<window
+	xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+	xmlns:html="http://www.w3.org/1999/xhtml">
+			<html:div>
+				<listitem>
+				</listitem>
+			</html:div>
+</window>
diff --git a/layout/xul/crashtests/289410-1.xul b/layout/xul/crashtests/289410-1.xul
new file mode 100644
index 0000000000..0de792f2c6
--- /dev/null
+++ b/layout/xul/crashtests/289410-1.xul
@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window id="crash-window"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+  <scrollbox>
+    <tree id="crash-tree">
+      <treecols/>
+      <treechildren/>
+    </tree>
+  </scrollbox>
+
+</window>
diff --git a/layout/xul/crashtests/290743.html b/layout/xul/crashtests/290743.html
new file mode 100644
index 0000000000..fd273d8bfb
--- /dev/null
+++ b/layout/xul/crashtests/290743.html
@@ -0,0 +1,6 @@
+<html>

+<head><title>Testcase bug 290743 - This display:-moz-grid testcase freezes Mozilla</title></head>

+<body style="display:-moz-grid;">

+<input type="radio"><input type="radio">

+</body>

+</html>
\ No newline at end of file
diff --git a/layout/xul/crashtests/291702-1.xul b/layout/xul/crashtests/291702-1.xul
new file mode 100644
index 0000000000..4c052630db
--- /dev/null
+++ b/layout/xul/crashtests/291702-1.xul
@@ -0,0 +1,11 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window title="Negative flex bug #2"
+		orient="horizontal"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <button label="Button" flex="2"/>
+  <label value="This is a label" flex="1"/>
+  <label value="This is the second label" flex="-2"/>
+  <label value="This is another label" flex="-1"/>
+</window>
diff --git a/layout/xul/crashtests/291702-2.xul b/layout/xul/crashtests/291702-2.xul
new file mode 100644
index 0000000000..53d8a51f72
--- /dev/null
+++ b/layout/xul/crashtests/291702-2.xul
@@ -0,0 +1,11 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window title="Negative flex bug #2"
+		orient="horizontal"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <button label="Button" flex="1073741824"/>
+  <label value="This is a label" flex="1073741824"/>
+  <label value="This is the second label" flex="1073741824"/>
+  <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+</window>
diff --git a/layout/xul/crashtests/291702-3.xul b/layout/xul/crashtests/291702-3.xul
new file mode 100644
index 0000000000..b34404f369
--- /dev/null
+++ b/layout/xul/crashtests/291702-3.xul
@@ -0,0 +1,137 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window title="Negative flex bug #2"
+		orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <hbox>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+  </hbox>
+
+  <hbox>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+  </hbox>
+
+
+  <hbox>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 2;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 2;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 2;"/>
+  </hbox>
+
+  <hbox>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+    <button label="Button" flex="1"/>
+    <label value="This is another label" style="-moz-box-flex: 1;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+    <button label="Button" flex="1"/>
+    <label value="This is another label" style="-moz-box-flex: 1;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+    <button label="Button" flex="1"/>
+    <label value="This is another label" style="-moz-box-flex: 1;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741823"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741823;"/>
+    <button label="Button" flex="2"/>
+    <label value="This is another label" style="-moz-box-flex: 2;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741824"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741824;"/>
+    <button label="Button" flex="2"/>
+    <label value="This is another label" style="-moz-box-flex: 2;"/>
+  </hbox>
+  <hbox>
+    <button label="Button" flex="1073741825"/>
+    <label value="This is another label" style="-moz-box-flex: 1073741825;"/>
+    <button label="Button" flex="2"/>
+    <label value="This is another label" style="-moz-box-flex: 2;"/>
+  </hbox>
+</window>
diff --git a/layout/xul/crashtests/294371-1.xul b/layout/xul/crashtests/294371-1.xul
new file mode 100644
index 0000000000..ca5b54914a
--- /dev/null
+++ b/layout/xul/crashtests/294371-1.xul
@@ -0,0 +1,53 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/global.css" type="text/css"?>
+
+<window
+  id    = "overflow crash"
+  title = "scrollbox crasher"
+  xmlns = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+	persist="sizemode width height screenX screenY"
+	width="320"
+	height="240">
+
+	<scrollbox flex="1">
+			<grid style="overflow: auto">
+				<columns>
+					<column flex="0"/>
+				</columns>
+				<rows>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+					<row><label value="Date"/></row>
+				</rows>
+			</grid>
+		</scrollbox>
+
+</window>
diff --git a/layout/xul/crashtests/311457-1.html b/layout/xul/crashtests/311457-1.html
new file mode 100644
index 0000000000..e5b6ecdd63
--- /dev/null
+++ b/layout/xul/crashtests/311457-1.html
@@ -0,0 +1,12 @@
+<html><head>
+
+</head>
+
+<body>
+
+<div style="display: -moz-deck"><div style="display: -moz-popup"></div></div>
+
+<div style="position: relative">Y</div>
+
+</body>
+</html>
\ No newline at end of file
diff --git a/layout/xul/crashtests/321056-1.xhtml b/layout/xul/crashtests/321056-1.xhtml
new file mode 100644
index 0000000000..a7ba117938
--- /dev/null
+++ b/layout/xul/crashtests/321056-1.xhtml
@@ -0,0 +1,10 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

+<xul:titlebar id="a"/>

+

+<script>

+var html = document.firstChild;

+var a = document.getElementById('a')

+document.removeChild(html)

+document.appendChild(a)

+</script>

+</html>

diff --git a/layout/xul/crashtests/322786-1.xul b/layout/xul/crashtests/322786-1.xul
new file mode 100644
index 0000000000..79bb092c4b
--- /dev/null
+++ b/layout/xul/crashtests/322786-1.xul
@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <foo style="display: inline;">
+    <scrollbox/>
+  </foo>
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/325377.xul b/layout/xul/crashtests/325377.xul
new file mode 100644
index 0000000000..8ea30473d8
--- /dev/null
+++ b/layout/xul/crashtests/325377.xul
@@ -0,0 +1,16 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" xmlns:html="http://www.w3.org/1999/xhtml"
+ title="Testcase bug 325377 - Crash on reload with evil xul textcase, using menulist and nested tooltips">
+<menulist style="display: table-cell;">
+<tooltip style="display: none;">
+    <tooltip/>
+</tooltip>
+</menulist>
+
+<html:script>
+function removestyles(){
+document.getElementsByTagName('tooltip')[0].removeAttribute('style');
+}
+try { document.getElementsByTagName('tooltip')[0].offsetHeight; } catch(e) {}
+setTimeout(removestyles,0);
+</html:script>
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/326834-1-inner.xul b/layout/xul/crashtests/326834-1-inner.xul
new file mode 100644
index 0000000000..0fbdca7ab2
--- /dev/null
+++ b/layout/xul/crashtests/326834-1-inner.xul
@@ -0,0 +1,17 @@
+<window title="Testcase bug 326834 - Crash with evil xul testcase, using listbox/listitem and display: table-cell"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<listbox>
+  <listitem label="This page should not crash Mozilla"/>
+</listbox>
+<html:script>
+function doe() {
+var el=document.getElementsByTagName('*');
+document.getElementsByTagName('listbox')[0].style.display = 'table-cell';
+document.getElementsByTagName('listitem')[0].style.display = 'table-cell';
+window.getComputedStyle(document.getElementsByTagName('listitem')[0], '').getPropertyValue("height");
+document.getElementsByTagName('listitem')[0].style.display = '';
+}
+setTimeout(doe,500);
+</html:script>
+</window>
diff --git a/layout/xul/crashtests/326834-1.html b/layout/xul/crashtests/326834-1.html
new file mode 100644
index 0000000000..ca531caa61
--- /dev/null
+++ b/layout/xul/crashtests/326834-1.html
@@ -0,0 +1,9 @@
+<html class="reftest-wait">
+<head>
+<script>
+setTimeout('document.documentElement.className = ""', 1000);
+</script>
+<body>
+<iframe src="326834-1-inner.xul"></iframe>
+</body>
+</html>
diff --git a/layout/xul/crashtests/326879-1.xul b/layout/xul/crashtests/326879-1.xul
new file mode 100644
index 0000000000..84d74c30cd
--- /dev/null
+++ b/layout/xul/crashtests/326879-1.xul
@@ -0,0 +1,31 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+
+
+<script>
+
+
+function init() { 
+
+  var menupopup = document.getElementsByTagName("menupopup")[0];
+  menupopup.ordinal = null;
+};
+
+
+window.addEventListener("load", init, false);
+
+</script>
+
+
+<menulist>
+  <menupopup>
+    <menuitem label="Foo"/>
+  </menupopup>
+</menulist>
+
+        
+
+</window>
diff --git a/layout/xul/crashtests/327776-1.xul b/layout/xul/crashtests/327776-1.xul
new file mode 100644
index 0000000000..af889493cd
--- /dev/null
+++ b/layout/xul/crashtests/327776-1.xul
@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<script>
+<![CDATA[
+function init()
+{ 
+  var span = document.getElementsByTagName("span")[0]; 
+  var boxobj = document.getBoxObjectFor(span);
+  try {
+    boxobj.setPropertyAsSupports(undefined, undefined);
+  } catch(e) {
+  }
+}
+window.addEventListener("load", init, false);
+]]>
+</script>
+
+<body xmlns="http://www.w3.org/1999/xhtml">
+
+<span></span>
+
+</body>
+</window>
diff --git a/layout/xul/crashtests/328135-1.xul b/layout/xul/crashtests/328135-1.xul
new file mode 100644
index 0000000000..77a4679099
--- /dev/null
+++ b/layout/xul/crashtests/328135-1.xul
@@ -0,0 +1,27 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+
+
+<script>
+
+function init() { 
+  var pop = document.getElementsByTagName("popup")[0];
+  SpecialPowers.wrap(document).getAnonymousNodes(pop)[0];
+  eval.eee = document.documentElement;
+};
+
+
+window.addEventListener("load", init, false);
+
+</script>
+
+<popup/>
+
+
+<tabbox/>
+
+
+</window>
diff --git a/layout/xul/crashtests/329327-1.xul b/layout/xul/crashtests/329327-1.xul
new file mode 100644
index 0000000000..fcfed07c4c
--- /dev/null
+++ b/layout/xul/crashtests/329327-1.xul
@@ -0,0 +1,2 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"><menulist equalsize="always"><y/> <z width="-444981589286"/> </menulist></window>
diff --git a/layout/xul/crashtests/329407-1.xml b/layout/xul/crashtests/329407-1.xml
new file mode 100644
index 0000000000..0d41c0185f
--- /dev/null
+++ b/layout/xul/crashtests/329407-1.xml
@@ -0,0 +1,14 @@
+<html xmlns="http://www.w3.org/1999/xhtml"
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+      >
+
+<body>
+
+  <xul:hbox>
+    <select/>
+    <select/>
+  </xul:hbox>
+
+</body>
+
+</html>
diff --git a/layout/xul/crashtests/329477-1.xhtml b/layout/xul/crashtests/329477-1.xhtml
new file mode 100644
index 0000000000..fcbd3da872
--- /dev/null
+++ b/layout/xul/crashtests/329477-1.xhtml
@@ -0,0 +1,31 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+
+<script>
+
+<![CDATA[
+
+
+function init() 
+{ 
+  var textbox = document.getElementsByTagName("textbox")[0];
+  var hbox = SpecialPowers.wrap(document).getAnonymousNodes(textbox)[0];
+  var menupopup = SpecialPowers.wrap(document).getAnonymousNodes(hbox)[1];
+
+  menupopup.click();
+}
+
+window.addEventListener("load", init, false);
+
+]]>
+</script>
+
+</head>
+
+<body>
+
+
+  <textbox xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"/>
+
+</body>
+</html>
diff --git a/layout/xul/crashtests/336962-1.xul b/layout/xul/crashtests/336962-1.xul
new file mode 100644
index 0000000000..5ad4ad22b8
--- /dev/null
+++ b/layout/xul/crashtests/336962-1.xul
@@ -0,0 +1,17 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<script>

+
+function init() { 
+  document.getElementById("foopy").style.position = "absolute";   
+}

+
+window.addEventListener("load", init, 0);

+
+</script>
+
+
+<box id="foopy" />
+       
+
+</window>
diff --git a/layout/xul/crashtests/344228-1.xul b/layout/xul/crashtests/344228-1.xul
new file mode 100644
index 0000000000..d6015707bd
--- /dev/null
+++ b/layout/xul/crashtests/344228-1.xul
@@ -0,0 +1,27 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="setTimeout(boom, 30);" class="reftest-wait">
+
+<script>
+
+function remove(q1) { q1.parentNode.removeChild(q1); } 
+
+function boom()
+{
+  var x = document.getElementById("x");
+  var y = document.getElementById("y");
+  remove(x);
+  remove(y);
+  
+  document.documentElement.removeAttribute("class");
+}
+
+</script>
+
+<tree>
+  <treechildren id="y"/>
+  <richlistbox>
+    <hbox id="x"/>
+    <menulist/>
+  </richlistbox>
+</tree>
+
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/346083-1.xul b/layout/xul/crashtests/346083-1.xul
new file mode 100644
index 0000000000..e04d610a4f
--- /dev/null
+++ b/layout/xul/crashtests/346083-1.xul
@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<body xmlns="http://www.w3.org/1999/xhtml">
+
+<script>
+<![CDATA[
+document.getBoxObjectFor(document.getElementsByTagName("body")[0]).setProperty("foo", undefined);
+]]>
+</script>
+
+</body>
+</window>
diff --git a/layout/xul/crashtests/346281-1.xul b/layout/xul/crashtests/346281-1.xul
new file mode 100644
index 0000000000..4ef6701558
--- /dev/null
+++ b/layout/xul/crashtests/346281-1.xul
@@ -0,0 +1,17 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<body xmlns="http://www.w3.org/1999/xhtml">
+
+<script>
+<![CDATA[
+var boxy = document.getBoxObjectFor(document.getElementsByTagName("body")[0]);
+boxy.setPropertyAsSupports("zoink", undefined);
+try {
+  boxy.removeProperty(undefined);
+} catch(e) { }
+]]>
+</script>
+
+</body>
+</window>
diff --git a/layout/xul/crashtests/350460.xul b/layout/xul/crashtests/350460.xul
new file mode 100644
index 0000000000..b13de6c977
--- /dev/null
+++ b/layout/xul/crashtests/350460.xul
@@ -0,0 +1,8 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"

+ title="Crash [@ DoDeletingFrameSubtree] after reloading a xul page a few times with display: -moz-popup and menuitem">

+  <menuitem style="display: -moz-popup;">

+    <box style="display: -moz-popup;">

+      <box style="display: -moz-popup;"/>

+    </box>

+  </menuitem>

+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/360642-1.xul b/layout/xul/crashtests/360642-1.xul
new file mode 100644
index 0000000000..5e37020a55
--- /dev/null
+++ b/layout/xul/crashtests/360642-1.xul
@@ -0,0 +1,9 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" 
+        class="reftest-wait"
+        onload="setTimeout(function() { var foo = document.getElementById('foo'); foo.parentNode.removeChild(foo); document.documentElement.removeAttribute('class'); }, 30);">
+        
+  <listboxbody>
+    <hbox id="foo"/>
+  </listboxbody>
+  
+</window>
diff --git a/layout/xul/crashtests/365151.xul b/layout/xul/crashtests/365151.xul
new file mode 100644
index 0000000000..074c8d398c
--- /dev/null
+++ b/layout/xul/crashtests/365151.xul
@@ -0,0 +1,39 @@
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="boom()" class="reftest-wait">
+
+
+<script>
+function boom()
+{
+ try {
+  var tree = document.getElementById("tree");
+  var col = tree.treeBoxObject.columns.getFirstColumn();
+  var treecols = document.getElementById("treecols");
+  treecols.parentNode.removeChild(treecols);
+  var x = col.x;
+ } finally {
+  document.documentElement.removeAttribute("class");
+ }
+}
+</script>
+
+
+<tree rows="6" id="tree">
+
+  <treecols id="treecols">
+      <treecol id="firstname" label="First Name"/>
+  </treecols>
+
+  <treechildren id="treechildren">
+    <treeitem>
+      <treerow>
+        <treecell label="Bob"/>
+      </treerow>
+    </treeitem>
+  </treechildren>
+
+</tree>
+
+</window>
diff --git a/layout/xul/crashtests/366112-1.xul b/layout/xul/crashtests/366112-1.xul
new file mode 100644
index 0000000000..4a03ea2cfd
--- /dev/null
+++ b/layout/xul/crashtests/366112-1.xul
@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+  <nativescrollbar />
+
+</window>
diff --git a/layout/xul/crashtests/366203-1.xul b/layout/xul/crashtests/366203-1.xul
new file mode 100644
index 0000000000..3e2b96d30d
--- /dev/null
+++ b/layout/xul/crashtests/366203-1.xul
@@ -0,0 +1,40 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="setTimeout(boom, 500);">
+
+<script>
+function boom()
+{
+  tc1 = document.getElementById("tc1");
+  tc1.parentNode.removeChild(tc1);
+}
+</script>
+
+<tree rows="6">
+  <treecols>
+      <treecol id="firstname" label="First Name" primary="true" flex="3"/>
+      <treecol id="lastname" label="Last Name" flex="7"/>
+  </treecols>
+
+  <treechildren id="tc1">
+    <treeitem container="true" open="true">
+      <treerow>
+        <treecell label="Foo"/>
+      </treerow>
+    </treeitem>
+  </treechildren>
+
+  <treechildren>
+    <treeitem container="true" open="true">
+      <treerow>
+        <treecell label="Bar"/>
+      </treerow>
+    </treeitem>
+  </treechildren>
+</tree>
+
+
+</window>
+
diff --git a/layout/xul/crashtests/367185-1.xhtml b/layout/xul/crashtests/367185-1.xhtml
new file mode 100644
index 0000000000..08fd39fa11
--- /dev/null
+++ b/layout/xul/crashtests/367185-1.xhtml
@@ -0,0 +1,11 @@
+<?xml version="1.0"?>

+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"

+    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

+<head>

+<title>Testcase bug - ASSERTION: shouldn't use unconstrained widths anymore with nested marquees</title>

+</head>

+<body>

+<xul:hbox style="margin: 0 100%;"><span><xul:hbox style="margin: 0 100%;"></xul:hbox></span></xul:hbox>

+</body>

+</html>

diff --git a/layout/xul/crashtests/369942-1.xhtml b/layout/xul/crashtests/369942-1.xhtml
new file mode 100644
index 0000000000..a05705843d
--- /dev/null
+++ b/layout/xul/crashtests/369942-1.xhtml
@@ -0,0 +1,36 @@
+<html xmlns="http://www.w3.org/1999/xhtml"

+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"

+      class="reftest-wait">

+<head>

+

+<script>

+function boom()

+{

+  var span = document.getElementById("span");

+  var radio = document.getElementById("radio");

+  

+  radio.appendChild(span);

+  

+  document.documentElement.removeAttribute("class");

+}

+</script>

+

+

+<style>

+body {

+	text-align: center;

+	font-size: 9px;

+}

+</style>

+

+</head>

+

+

+<body onload="setTimeout(boom, 30);">

+

+<span id="span"><xul:wizard/><div>Industries</div></span>

+

+<xul:radio id="radio"/>

+

+</body>

+</html>

diff --git a/layout/xul/crashtests/374102-1.xul b/layout/xul/crashtests/374102-1.xul
new file mode 100644
index 0000000000..7e85f0d21c
--- /dev/null
+++ b/layout/xul/crashtests/374102-1.xul
@@ -0,0 +1,5 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

+<tabpanels>

+<treechildren style="display: -moz-deck;"/>

+</tabpanels>

+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/376137-1.html b/layout/xul/crashtests/376137-1.html
new file mode 100644
index 0000000000..23b39d900c
--- /dev/null
+++ b/layout/xul/crashtests/376137-1.html
@@ -0,0 +1,18 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+<style>
+span { display:block; outline: 10px solid yellow; }
+</style>
+</head>
+
+<body>
+
+<div>
+  <div style="display: -moz-inline-grid">
+    <span>M</span>
+    <span>N</span>
+  </div>
+</div>
+
+</body>
+</html>
diff --git a/layout/xul/crashtests/376137-2.html b/layout/xul/crashtests/376137-2.html
new file mode 100644
index 0000000000..160c61ed31
--- /dev/null
+++ b/layout/xul/crashtests/376137-2.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>

+<title>Bug 376137</title>

+<style>

+p { width: 100%; border: solid 1px;}

+</style>

+

+<div style="display: -moz-inline-grid">

+  <div><p>M</p></div>

+  <div><p>N</p></div>

+</div>

+

diff --git a/layout/xul/crashtests/377592-1.svg b/layout/xul/crashtests/377592-1.svg
new file mode 100644
index 0000000000..7371708f24
--- /dev/null
+++ b/layout/xul/crashtests/377592-1.svg
@@ -0,0 +1,27 @@
+<svg xmlns="http://www.w3.org/2000/svg" 
+     xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+     onload="setTimeout(boom, 30);"
+     class="reftest-wait">
+
+
+<script>
+
+var emptyBinding = "url('data:text/xml,%3Cbindings%20xmlns%3D%22http%3A%2F%2Fwww.mozilla.org%2Fxbl%22%3E%3Cbinding%20id%3D%22foo%22%3E%3Ccontent%3E%0A%0A%20%20%20%20%0A%3C%2Fcontent%3E%3C%2Fbinding%3E%3C%2Fbindings%3E%0A')";
+
+function boom()
+{
+  var foreignObject = document.getElementById("foreignObject")
+  foreignObject.style.MozBinding = emptyBinding;
+
+  document.documentElement.removeAttribute("class");
+}
+
+</script>
+
+
+<foreignObject width="500" height="500" transform="scale(.7,.7)" id="foreignObject" y="300">
+  <xul:menuitem />
+</foreignObject>
+
+
+</svg>
diff --git a/layout/xul/crashtests/378961.html b/layout/xul/crashtests/378961.html
new file mode 100644
index 0000000000..b4da857ff3
--- /dev/null
+++ b/layout/xul/crashtests/378961.html
@@ -0,0 +1,9 @@
+<html>

+<head>

+<title>Testcase bug 378961 - Crash [@ nsSplitterFrameInner::RemoveListener] when dragging splitter and DOMAttrModified event removing window</title>

+</head>

+<body>

+<iframe src="data:application/vnd.mozilla.xul+xml;charset=utf-8,%3C%3Fxml%20version%3D%221.0%22%3F%3E%0A%3C%3Fxml-stylesheet%20href%3D%22chrome%3A//global/skin%22%20type%3D%22text/css%22%3F%3E%0A%3Cwindow%20xmlns%3D%22http%3A//www.mozilla.org/keymaster/gatekeeper/there.is.only.xul%22%20orient%3D%22horizontal%22%3E%0A%3Ctextbox/%3E%3Csplitter/%3E%3Cbox/%3E%0A%0A%3Cscript%20xmlns%3D%22http%3A//www.w3.org/1999/xhtml%22%3E%0Afunction%20doe%28%29%20%7B%0Awindow.frameElement.parentNode.removeChild%28window.frameElement%29%3B%0A%7D%0Adocument.addEventListener%28%27DOMAttrModified%27%2C%20doe%2C%20true%29%3B%0A%3C/script%3E%0A%3C/window%3E" style="width: 500px;height:200px;"></iframe>

+

+</body>

+</html>

diff --git a/layout/xul/crashtests/381862.html b/layout/xul/crashtests/381862.html
new file mode 100644
index 0000000000..e26fa357e7
--- /dev/null
+++ b/layout/xul/crashtests/381862.html
@@ -0,0 +1,23 @@
+<html><head>

+<title>Testcase bug - Crash [@ nsBoxFrame::BuildDisplayListForChildren] with tree stuff in iframe toggling display</title>

+</head>

+<body>

+<iframe src="data:application/vnd.mozilla.xul+xml;charset=utf-8,%3Cwindow%20xmlns%3D%22http%3A//www.mozilla.org/keymaster/gatekeeper/there.is.only.xul%22%3E%0A%20%20%3Ctree%20style%3D%22display%3A%20block%3B%20position%3A%20absolute%3B%22%3E%0A%20%20%20%20%3Ctree%20style%3D%22display%3A%20table%3B%22%3E%0A%20%20%20%20%20%20%3Ctreeseparator%20style%3D%22display%3A%20block%3B%20position%3A%20absolute%3B%22%3E%0A%20%20%20%20%20%20%20%20%3Ctreechildren%20style%3D%22display%3A%20block%3B%22/%3E%0A%20%20%20%20%20%20%3C/treeseparator%3E%0A%20%20%20%20%20%20%3Ctreechildren%20style%3D%22display%3A%20none%3B%22/%3E%0A%20%20%20%20%3C/tree%3E%0A%20%20%3C/tree%3E%0A%3C/window%3E" id="content"></iframe>

+

+<script>

+function toggleIframe(){

+var x=document.getElementById('content');

+x.style.display = x.style.display == 'none' ? x.style.display = 'block' : x.style.display = 'none';

+setTimeout(toggleIframe,200);

+}

+setTimeout(toggleIframe,500);

+

+function removestyles(i){

+window.frames[0].document.getElementsByTagName('*')[1].removeAttribute('style');

+}

+

+setTimeout(removestyles,500,1);

+/*template*/

+</script>

+</body>

+</html>

diff --git a/layout/xul/crashtests/382746-1.xul b/layout/xul/crashtests/382746-1.xul
new file mode 100644
index 0000000000..9bb14f24fa
--- /dev/null
+++ b/layout/xul/crashtests/382746-1.xul
@@ -0,0 +1,15 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<grid>
+  <rows>
+    <column>
+      <hbox/>
+      <hbox/>
+    </column>
+    <hbox/>
+  </rows>
+</grid>
+
+</window>
diff --git a/layout/xul/crashtests/382899-1.xul b/layout/xul/crashtests/382899-1.xul
new file mode 100644
index 0000000000..7dab931f7d
--- /dev/null
+++ b/layout/xul/crashtests/382899-1.xul
@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<hbox equalsize="always"><grid/>x</hbox>
+
+</window>
diff --git a/layout/xul/crashtests/383236-1.xul b/layout/xul/crashtests/383236-1.xul
new file mode 100644
index 0000000000..244df65f11
--- /dev/null
+++ b/layout/xul/crashtests/383236-1.xul
@@ -0,0 +1,5 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<listbox><listhead>x</listhead></listbox>
+
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/384037-1.xhtml b/layout/xul/crashtests/384037-1.xhtml
new file mode 100644
index 0000000000..04bac671cc
--- /dev/null
+++ b/layout/xul/crashtests/384037-1.xhtml
@@ -0,0 +1,9 @@
+<html xmlns="http://www.w3.org/1999/xhtml" 

+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

+<body>

+

+<xul:splitter id="s" collapse="both" state="collapsed" />

+

+</body>

+</html>

+

diff --git a/layout/xul/crashtests/384105-1-inner.xul b/layout/xul/crashtests/384105-1-inner.xul
new file mode 100644
index 0000000000..4ea6e03911
--- /dev/null
+++ b/layout/xul/crashtests/384105-1-inner.xul
@@ -0,0 +1,21 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<script id="script" xmlns="http://www.w3.org/1999/xhtml">
+function doe(){
+document.getElementById('a').removeAttribute('style');
+}
+setTimeout(doe,100);
+</script>
+<box id="a" style="position: absolute;">
+  <menuitem sizetopopup="always">
+    <menupopup style="position: absolute;"/>
+  </menuitem>
+
+  <box style="position: fixed;">
+    <tree>
+      <treecol>
+        <treecol/>
+      </treecol>
+    </tree>
+  </box>
+</box>
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/384105-1.html b/layout/xul/crashtests/384105-1.html
new file mode 100644
index 0000000000..fe468a9069
--- /dev/null
+++ b/layout/xul/crashtests/384105-1.html
@@ -0,0 +1,9 @@
+<html class="reftest-wait">
+<head>
+<script>
+setTimeout('document.documentElement.className = ""', 1000);
+</script>
+<body>
+<iframe src="384105-1-inner.xul"></iframe>
+</body>
+</html>
diff --git a/layout/xul/crashtests/384373-1.xul b/layout/xul/crashtests/384373-1.xul
new file mode 100644
index 0000000000..603b53cdea
--- /dev/null
+++ b/layout/xul/crashtests/384373-1.xul
@@ -0,0 +1,10 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" 

+onerror="var x=document.getElementsByTagName('*');x[Math.floor(Math.random()*x.length)].focus()"

+onblur="event.originalTarget.parentNode.parentNode.removeChild(event.originalTarget.parentNode)">

+<script xmlns="http://www.w3.org/1999/xhtml">setTimeout(function() {window.location.reload()}, 200);</script>

+

+<broadcasterset style="display: block;">

+  <broadcaster style="display: block;"></broadcaster>

+</broadcasterset>

+<preferences></preferences>

+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/384373-2.xul b/layout/xul/crashtests/384373-2.xul
new file mode 100644
index 0000000000..1d56394e31
--- /dev/null
+++ b/layout/xul/crashtests/384373-2.xul
@@ -0,0 +1,4 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onerror="document.getElementsByTagName('*')[1].focus()" onfocus="event.target.parentNode.removeChild(event.target)">

+<broadcaster style="display: block;"/>

+<preferences/>

+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/384373.html b/layout/xul/crashtests/384373.html
new file mode 100644
index 0000000000..c3bc92f16a
--- /dev/null
+++ b/layout/xul/crashtests/384373.html
@@ -0,0 +1,23 @@
+<!DOCTYPE HTML>
+<html class="reftest-wait"><head>
+    <meta charset="utf-8">
+    <title>Testcase for bug 384373</title>
+<script>
+function reload() {
+  this.location.reload();
+}
+// Run the test for 1 second
+setTimeout(function() {
+    document.body.getBoundingClientRect();
+    document.documentElement.removeChild(document.body);
+    document.documentElement.className = "";
+  }, 2000);
+</script>
+</head>
+<body onload="document.body.getBoundingClientRect()">
+
+<iframe src="384373-1.xul"></iframe>
+<iframe onload="this.contentWindow.setTimeout(reload,500)" src="384373-2.xul"></iframe>
+
+</body>
+</html>
diff --git a/layout/xul/crashtests/384491-1.xhtml b/layout/xul/crashtests/384491-1.xhtml
new file mode 100644
index 0000000000..2eb065f8d2
--- /dev/null
+++ b/layout/xul/crashtests/384491-1.xhtml
@@ -0,0 +1,8 @@
+<html xmlns="http://www.w3.org/1999/xhtml" 
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<body>
+
+<xul:listboxbody style="overflow: hidden" />
+
+</body>
+</html>
diff --git a/layout/xul/crashtests/384871-1-inner.xul b/layout/xul/crashtests/384871-1-inner.xul
new file mode 100644
index 0000000000..62efdb2608
--- /dev/null
+++ b/layout/xul/crashtests/384871-1-inner.xul
@@ -0,0 +1,9 @@
+<popup xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<script xmlns="http://www.w3.org/1999/xhtml">
+function doe(){
+document.documentElement.autoPosition = 'on';
+window.location.reload();
+}
+setTimeout(doe, 300);
+</script>
+</popup>
\ No newline at end of file
diff --git a/layout/xul/crashtests/384871-1.html b/layout/xul/crashtests/384871-1.html
new file mode 100644
index 0000000000..6bb2a9e07b
--- /dev/null
+++ b/layout/xul/crashtests/384871-1.html
@@ -0,0 +1,9 @@
+<html class="reftest-wait">
+<head>
+<script>
+setTimeout('document.documentElement.className = ""', 500);
+</script>
+<body>
+<iframe src="384871-1-inner.xul"></iframe>
+</body>
+</html>
diff --git a/layout/xul/crashtests/386642.xul b/layout/xul/crashtests/386642.xul
new file mode 100644
index 0000000000..50db21a095
--- /dev/null
+++ b/layout/xul/crashtests/386642.xul
@@ -0,0 +1,31 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="Bug 386642 Crash [@ IsCanvasFrame] while opening context menu or changing styles">
+<toolbarbutton type="menu" id="a">
+<menupopup id="b"/>
+</toolbarbutton>
+
+<style xmlns="http://www.w3.org/1999/xhtml">
+.one image {
+display: -moz-box;
+}
+image{
+display: none;
+}
+
+</style>
+<script><![CDATA[
+var gg=0;
+function doe() {
+  var a = document.getElementById('a');
+  if (!a.hasAttribute('class')) {
+    a.setAttribute('class', 'one');
+  } else {
+    a.removeAttribute('class');
+  }
+document.getElementById('b').hidePopup();
+}
+
+doe();
+setInterval(doe, 200);
+]]></script>
+</window>
diff --git a/layout/xul/crashtests/387033-1.xhtml b/layout/xul/crashtests/387033-1.xhtml
new file mode 100644
index 0000000000..58325b1a79
--- /dev/null
+++ b/layout/xul/crashtests/387033-1.xhtml
@@ -0,0 +1,31 @@
+<?xml version="1.0"?>
+<html xmlns="http://www.w3.org/1999/xhtml"
+      xmlns:xbl="http://www.mozilla.org/xbl"
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <head>
+    <xbl:bindings>
+      <xbl:binding id="test" extends="chrome://global/content/bindings/text.xml#text-label">
+        <xbl:implementation>
+          <xbl:property name="accessKey">
+            <xbl:getter>
+              <![CDATA[
+                this.parentNode.parentNode.removeChild(this.parentNode);
+                return "";
+              ]]>
+            </xbl:getter>
+            <xbl:setter>
+              <![CDATA[
+                return val;
+              ]]>
+            </xbl:setter>
+          </xbl:property>
+        </xbl:implementation>
+      </xbl:binding>
+    </xbl:bindings>
+  </head>
+  <body>
+    <xul:hbox>
+      <xul:label value="foobar" style="-moz-binding: url(#test)"/>
+    </xul:hbox>
+  </body>
+</html>
diff --git a/layout/xul/crashtests/387080-1.xul b/layout/xul/crashtests/387080-1.xul
new file mode 100644
index 0000000000..4eb9bd784b
--- /dev/null
+++ b/layout/xul/crashtests/387080-1.xul
@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <description>
+    <foo height="1793689537164611773" width="20000238421986669650" />
+  </description>
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/391974-1-inner.xul b/layout/xul/crashtests/391974-1-inner.xul
new file mode 100644
index 0000000000..f13aa2110f
--- /dev/null
+++ b/layout/xul/crashtests/391974-1-inner.xul
@@ -0,0 +1,19 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<menuitem>
+<tooltip/>
+<box/>
+</menuitem>
+
+<script xmlns="http://www.w3.org/1999/xhtml">
+function doe2() {
+document.getElementsByTagName('menuitem')[0].setAttribute('description', 'tetx');
+}
+
+function doe3() {
+document.getElementsByTagName('menuitem')[0].removeAttribute('description');
+document.getElementsByTagName('tooltip')[0].setAttribute('ordinal', '0');
+}
+setTimeout(doe2,150);
+setTimeout(doe3,200);
+</script>
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/391974-1.html b/layout/xul/crashtests/391974-1.html
new file mode 100644
index 0000000000..c72a1a73cc
--- /dev/null
+++ b/layout/xul/crashtests/391974-1.html
@@ -0,0 +1,9 @@
+<html class="reftest-wait">
+<head>
+<script>
+setTimeout('document.documentElement.className = ""', 1000);
+</script>
+<body>
+<iframe src="391974-1-inner.xul"></iframe>
+</body>
+</html>
diff --git a/layout/xul/crashtests/394120-1.xhtml b/layout/xul/crashtests/394120-1.xhtml
new file mode 100644
index 0000000000..9df4478621
--- /dev/null
+++ b/layout/xul/crashtests/394120-1.xhtml
@@ -0,0 +1,19 @@
+<html xmlns="http://www.w3.org/1999/xhtml" 
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<head>
+<script>
+function boom()
+{
+  var XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+  var xultext = document.createElementNS(XUL_NS, "text");
+  var hbox = document.getElementById("hbox")
+  hbox.appendChild(xultext);
+}
+</script>
+</head>
+<body onload="boom();">
+
+<xul:listboxbody><xul:hbox id="hbox" /></xul:listboxbody>
+
+</body>
+</html>
diff --git a/layout/xul/crashtests/397293.xhtml b/layout/xul/crashtests/397293.xhtml
new file mode 100644
index 0000000000..cfd1819215
--- /dev/null
+++ b/layout/xul/crashtests/397293.xhtml
@@ -0,0 +1,21 @@
+<html xmlns="http://www.w3.org/1999/xhtml"  
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+      style="opacity: 0.2;">
+<head>
+<script>
+
+function x()
+{
+  document.documentElement.style.counterReset = "chicken";
+  
+  document.body.offsetHeight;
+}
+
+</script>
+</head>
+
+<body onload="setTimeout(x, 0);">Foo</body>
+
+<xul:listbox/>
+
+</html>
diff --git a/layout/xul/crashtests/397304-1.html b/layout/xul/crashtests/397304-1.html
new file mode 100644
index 0000000000..3501f05811
--- /dev/null
+++ b/layout/xul/crashtests/397304-1.html
@@ -0,0 +1 @@
+<html><body><listboxbody style="display: -moz-grid-group;"></listboxbody></body></html>
\ No newline at end of file
diff --git a/layout/xul/crashtests/398326-1.xhtml b/layout/xul/crashtests/398326-1.xhtml
new file mode 100644
index 0000000000..a265ae4e00
--- /dev/null
+++ b/layout/xul/crashtests/398326-1.xhtml
@@ -0,0 +1,17 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+<script>
+var XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+
+function boom()
+{
+  var listbox = document.createElementNS(XUL_NS, 'listbox');
+  document.body.appendChild(listbox);
+  var listitem = document.createElementNS(XUL_NS, 'listitem');
+  listbox.appendChild(listitem);
+}
+</script>
+</head>
+<body onload="boom();">
+</body>
+</html>
diff --git a/layout/xul/crashtests/399013.xul b/layout/xul/crashtests/399013.xul
new file mode 100644
index 0000000000..a2349aff84
--- /dev/null
+++ b/layout/xul/crashtests/399013.xul
@@ -0,0 +1,31 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<menulist id="b" style="display: -moz-groupbox;">
+<panel id="c" style=" position: absolute;">
+<popup onunderflow="document.getElementById('c').removeAttribute('style')"/>
+</panel>
+<menupopup id="a" style="display: -moz-stack;">
+<menulist/>
+</menupopup>
+<panel style="display: -moz-deck;" onoverflow="document.getElementById('b').removeAttribute('style')">
+<popup style="display: -moz-deck;"/>
+</panel>
+</menulist>
+

+<script id="script" xmlns="http://www.w3.org/1999/xhtml"><![CDATA[

+function doe() {

+document.getElementById('c').removeAttribute('style');

+document.documentElement.boxObject.height;

+document.getElementById('b').removeAttribute('style');

+document.getElementById('a').setAttribute('selected', 'true');

+document.getElementById('a').setAttribute('style', 'position: fixed;');

+document.documentElement.boxObject.height;

+document.getElementById('a').removeAttribute('style');

+}

+

+function doe2() {

+window.location.reload();

+}

+setTimeout(doe2, 200);

+setTimeout(doe,100);

+]]></script>

+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/400779-1.xhtml b/layout/xul/crashtests/400779-1.xhtml
new file mode 100644
index 0000000000..c0f5d493c7
--- /dev/null
+++ b/layout/xul/crashtests/400779-1.xhtml
@@ -0,0 +1,16 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<head>
+<script>
+
+function boom()
+{
+  var menulist = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "menulist");
+  document.getElementById("h").appendChild(menulist);
+}
+
+</script>
+</head>
+<body onload="boom();">
+<xul:listboxbody><xul:hbox id="h"/></xul:listboxbody>
+</body>
+</html>
diff --git a/layout/xul/crashtests/402912-1.xhtml b/layout/xul/crashtests/402912-1.xhtml
new file mode 100644
index 0000000000..b2cb98dc5a
--- /dev/null
+++ b/layout/xul/crashtests/402912-1.xhtml
@@ -0,0 +1,5 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<body>
+<xul:vbox equalsize="always"><xul:hbox flex="1"><span><xul:hbox width="10" height="10"/></span><xul:button /></xul:hbox><xul:hbox maxheight="0"/></xul:vbox>
+</body>
+</html>
diff --git a/layout/xul/crashtests/404192.xhtml b/layout/xul/crashtests/404192.xhtml
new file mode 100644
index 0000000000..4ad5af348b
--- /dev/null
+++ b/layout/xul/crashtests/404192.xhtml
@@ -0,0 +1,12 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" class="reftest-wait">

+<xul:titlebar id="a" style="overflow: auto;"/>

+

+<script>

+function doe() {

+document.getElementsByTagName('*')[1].focus();

+document.getElementsByTagName('*')[0].focus();

+document.documentElement.removeAttribute("class");

+}

+setTimeout(doe, 200);

+</script>

+</html>

diff --git a/layout/xul/crashtests/407152.xul b/layout/xul/crashtests/407152.xul
new file mode 100644
index 0000000000..0a5adf69eb
--- /dev/null
+++ b/layout/xul/crashtests/407152.xul
@@ -0,0 +1,7 @@
+<triple xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" style="display: block;">
+<box style="display: block; position: relative; -moz-binding: url(data:text/xml;charset=utf-8,%3Cbindings%20xmlns%3D%22http%3A//www.mozilla.org/xbl%22%3E%0A%3Cbinding%20id%3D%22a%22%3E%0A%3Cimplementation%3E%0A%3Cfield%20name%3D%22_field%22%3Ethis.ownerDocument.getBoxObjectFor%28this.ownerDocument.documentElement%29%3B%3C/field%3E%0A%3C/implementation%3E%0A%3Ccontent%3E%0A%3C/binding%3E%0A%3C/bindings%3E);">
+<box style="position: fixed; -moz-binding: url(data:text/xml;charset=utf-8,%3Cbindings%20xmlns%3D%22http%3A//www.mozilla.org/xbl%22%3E%0A%3Cbinding%20id%3D%22a%22%3E%0A%3Ccontent%3E%0A%3Cchildren%20xmlns%3D%22http%3A//www.mozilla.org/xbl%22/%3E%3C/content%3E%3C/binding%3E%3C/bindings%3E);"/>
+<iframe/>
+</box>
+<scrollbox onoverflow="document.documentElement.removeAttribute('style')"/>
+</triple>
\ No newline at end of file
diff --git a/layout/xul/crashtests/408904-1.xul b/layout/xul/crashtests/408904-1.xul
new file mode 100644
index 0000000000..59f215c73b
--- /dev/null
+++ b/layout/xul/crashtests/408904-1.xul
@@ -0,0 +1 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"><grid><rows><label/></rows><columns><column><label/></column></columns></grid></window>
diff --git a/layout/xul/crashtests/412479-1.xhtml b/layout/xul/crashtests/412479-1.xhtml
new file mode 100644
index 0000000000..b1086a816e
--- /dev/null
+++ b/layout/xul/crashtests/412479-1.xhtml
@@ -0,0 +1,4 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<head></head>
+<body><xul:menubar style="display: table-column; padding: 10px 3000px;"/></body>
+</html>
diff --git a/layout/xul/crashtests/415394-1.xhtml b/layout/xul/crashtests/415394-1.xhtml
new file mode 100644
index 0000000000..7dc24dc9f7
--- /dev/null
+++ b/layout/xul/crashtests/415394-1.xhtml
@@ -0,0 +1,28 @@
+<html xmlns="http://www.w3.org/1999/xhtml" 
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+      class="reftest-wait">
+<head>
+<script type="text/javascript">
+
+function boom()
+{
+  document.execCommand("justifycenter", false, null);
+
+  var listboxbody = document.getElementById("lbb");
+  listboxbody.height = 9;
+  setTimeout(boom2, 0);
+
+  function boom2()
+  {
+    var td = document.createElementNS("http://www.w3.org/1999/xhtml", "td");
+    listboxbody.appendChild(td);
+    document.documentElement.removeAttribute("class");
+  }
+}
+
+</script>
+</head>
+
+<body onload="setTimeout(boom, 0);" contenteditable="true"><xul:listboxbody id="lbb"><xul:hbox/><span><col style="width: 100px;" /></span></xul:listboxbody></body>
+
+</html>
diff --git a/layout/xul/crashtests/417509.xul b/layout/xul/crashtests/417509.xul
new file mode 100644
index 0000000000..81703ada37
--- /dev/null
+++ b/layout/xul/crashtests/417509.xul
@@ -0,0 +1,7 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<span id="a" datasources="" xmlns="http://www.w3.org/1999/xhtml"/>
+<script xmlns="http://www.w3.org/1999/xhtml">
+document.documentElement.appendChild(document.getElementById('a'));
+
+</script>
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/420424-1.xul b/layout/xul/crashtests/420424-1.xul
new file mode 100644
index 0000000000..e608417065
--- /dev/null
+++ b/layout/xul/crashtests/420424-1.xul
@@ -0,0 +1,6 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="document.getElementById('a').ensureElementIsVisible(null);">
+
+<listbox id="a"/>
+
+</window>
diff --git a/layout/xul/crashtests/430356-1.xhtml b/layout/xul/crashtests/430356-1.xhtml
new file mode 100644
index 0000000000..6e5717ae94
--- /dev/null
+++ b/layout/xul/crashtests/430356-1.xhtml
@@ -0,0 +1,5 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+<body style="visibility: collapse;">
+<tabpanels xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" style="width: -moz-max-content;"></tabpanels>
+</body>
+</html>
diff --git a/layout/xul/crashtests/431738.xhtml b/layout/xul/crashtests/431738.xhtml
new file mode 100644
index 0000000000..9ce917a3fb
--- /dev/null
+++ b/layout/xul/crashtests/431738.xhtml
@@ -0,0 +1,7 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<body>
+<div>
+<span style="font-size: 0pt;"><xul:listboxbody><span style="border: 1px solid red;"/></xul:listboxbody></span>
+</div>
+</body>
+</html>
diff --git a/layout/xul/crashtests/432058-1.xul b/layout/xul/crashtests/432058-1.xul
new file mode 100644
index 0000000000..a7f63adf8d
--- /dev/null
+++ b/layout/xul/crashtests/432058-1.xul
@@ -0,0 +1,31 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="boom();">
+
+<script type="text/javascript">
+// <![CDATA[
+
+var XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+
+function boom()
+{
+  var lb = document.getElementById("lb");
+  var firstli = document.getElementById("firstli");
+  lb.appendChild(document.createElementNS(XUL_NS, "hbox"));
+  lb.appendChild(document.createElementNS(XUL_NS, "listitem"));
+  firstli.style.display = "none";
+
+  // Flush layout.
+  document.getBoxObjectFor(document.documentElement).height;
+
+  lb.removeChild(firstli);
+}
+
+// ]]>
+</script>
+
+<listbox id="lb"><listitem id="firstli"/></listbox>
+
+</window>
diff --git a/layout/xul/crashtests/432068-1.xul b/layout/xul/crashtests/432068-1.xul
new file mode 100644
index 0000000000..02c3114e61
--- /dev/null
+++ b/layout/xul/crashtests/432068-1.xul
@@ -0,0 +1,31 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="boom();">
+
+<hbox style="display: none;">
+  <bindings xmlns="http://www.mozilla.org/xbl">
+    <binding id="x">
+      <content><listitem xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"/></content>
+    </binding>
+  </bindings>
+</hbox>
+
+<script type="text/javascript">
+
+function boom()
+{
+  document.getElementById("b").style.MozBinding = "url('#x')";
+  
+  // Flush layout.
+  document.documentElement.boxObject.height;
+  
+  document.getElementById("listbox").removeChild(document.getElementById("c"));
+}
+
+</script>
+
+<listbox id="listbox"><listitem/><listitem id="b"/><listitem id="c"/></listbox>
+
+</window>
diff --git a/layout/xul/crashtests/432068-2.xul b/layout/xul/crashtests/432068-2.xul
new file mode 100644
index 0000000000..c75984bae9
--- /dev/null
+++ b/layout/xul/crashtests/432068-2.xul
@@ -0,0 +1,24 @@
+<?xml version="1.0"?>

+

+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>

+

+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="boom();">

+

+<script type="text/javascript">

+

+function boom()

+{

+  var l = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "listitem");

+  l.style.display = "none";

+

+  var c = document.getElementById("c");

+  c.parentNode.insertBefore(l, c);

+  

+  document.getElementById("listbox").removeChild(document.getElementById("c"));

+}

+

+</script>

+

+<listbox id="listbox"><listitem/><listitem id="c"/></listbox>

+

+</window>

diff --git a/layout/xul/crashtests/433296-1.xul b/layout/xul/crashtests/433296-1.xul
new file mode 100644
index 0000000000..10fd0ec7b3
--- /dev/null
+++ b/layout/xul/crashtests/433296-1.xul
@@ -0,0 +1,5 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<hbox><listboxbody><listheader/><hbox><iframe/></hbox></listboxbody><tabpanels><tabpanels/></tabpanels></hbox>
+
+</window>
diff --git a/layout/xul/crashtests/433429.xul b/layout/xul/crashtests/433429.xul
new file mode 100644
index 0000000000..a52bce68f9
--- /dev/null
+++ b/layout/xul/crashtests/433429.xul
@@ -0,0 +1,23 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="boom();">
+
+<script type="text/javascript">
+
+function boom()
+{
+  var listbox = document.getElementById("listbox");
+
+  listbox.removeChild(listbox.childNodes[1]);
+  document.documentElement.style.MozBinding = "url('data:text/xml,%3Cbindings%20xmlns%3D%22http%3A%2F%2Fwww.mozilla.org%2Fxbl%22%3E%3Cbinding%20id%3D%22foo%22%3E%3Ccontent%3E%0A%3Chbox%20xmlns%3D%22http%3A%2F%2Fwww.mozilla.org%2Fkeymaster%2Fgatekeeper%2Fthere.is.only.xul%22%2F%3E%0A%3C%2Fcontent%3E%3C%2Fbinding%3E%3C%2Fbindings%3E%0A')";
+  document.documentElement.boxObject.height;
+  listbox.removeChild(listbox.childNodes[0]);
+}
+
+</script>
+
+<listbox id="listbox" style="-moz-binding: url(data:text/xml,%3Cbindings%20xmlns%3D%22http%3A%2F%2Fwww.mozilla.org%2Fxbl%22%3E%3Cbinding%20id%3D%22foo%22%3E%3Ccontent%3E%0A%3Clistbox%20xmlns%3D%22http%3A%2F%2Fwww.mozilla.org%2Fkeymaster%2Fgatekeeper%2Fthere.is.only.xul%22%3E%3Cchildren%20xmlns%3D%22http%3A%2F%2Fwww.mozilla.org%2Fxbl%22%2F%3E%3C%2Flistbox%3E%0A%3C%2Fcontent%3E%3C%2Fbinding%3E%3C%2Fbindings%3E%0A);"><listitem/><listitem/></listbox>
+
+</window>
diff --git a/layout/xul/crashtests/434458-1.xul b/layout/xul/crashtests/434458-1.xul
new file mode 100644
index 0000000000..fbec2a4134
--- /dev/null
+++ b/layout/xul/crashtests/434458-1.xul
@@ -0,0 +1,20 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="setTimeout(boom, 30);" class="reftest-wait">
+
+<script>
+function boom() {
+  var a = document.getElementById('a');
+  var x = a.popupBoxObject;
+  a.parentNode.removeChild(a);
+  x.enableKeyboardNavigator(true);
+  x.openPopup(null, "after_start", 0, 0, false, false, null);
+  x.openPopupAtScreen(2, 2, false, null);
+  x.showPopup(document.documentElement, a, -1, -1, "popup", "topleft", "topleft");
+  x.hidePopup();
+  document.documentElement.removeAttribute("class");
+}
+
+</script>
+
+<menupopup id="a"/>
+
+</window>
diff --git a/layout/xul/crashtests/452185.html b/layout/xul/crashtests/452185.html
new file mode 100644
index 0000000000..d4981ffdf2
--- /dev/null
+++ b/layout/xul/crashtests/452185.html
@@ -0,0 +1,3 @@
+<html><head></head><body><div style="position: absolute;"> </div>

+<style>div, head {-moz-binding:url(452185.xml#a);</style>

+</body></html>

diff --git a/layout/xul/crashtests/452185.xml b/layout/xul/crashtests/452185.xml
new file mode 100644
index 0000000000..655c43a8d1
--- /dev/null
+++ b/layout/xul/crashtests/452185.xml
@@ -0,0 +1,5 @@
+<bindings xmlns="http://www.mozilla.org/xbl" xmlns:xlink="http://www.w3.org/1999/xlink">
+<binding id="a">
+<content><tbody xmlns="http://www.w3.org/1999/xhtml"><style>*::before { content:"b"; }</style></tbody></content>
+
+</binding></bindings>
\ No newline at end of file
diff --git a/layout/xul/crashtests/460900-1.xul b/layout/xul/crashtests/460900-1.xul
new file mode 100644
index 0000000000..bff7c5c36b
--- /dev/null
+++ b/layout/xul/crashtests/460900-1.xul
@@ -0,0 +1,3 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="document.getElementById('label').control='c';">
+<label id="label"><hbox><listboxbody><hbox/><tooltip/></listboxbody><autorepeatbutton/></hbox></label>
+</window>
diff --git a/layout/xul/crashtests/464149-1.xul b/layout/xul/crashtests/464149-1.xul
new file mode 100644
index 0000000000..556656f021
--- /dev/null
+++ b/layout/xul/crashtests/464149-1.xul
@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window onload="boom();" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<bindings xmlns="http://www.mozilla.org/xbl">
+  <binding id="m"><content><xul:textbox type="text"><children/></xul:textbox></content></binding>
+</bindings>
+
+<script type="text/javascript">
+<![CDATA[
+
+function boom()
+{
+  document.getElementById("b").style.MozBinding = 'url("data:text/xml,' + encodeURIComponent("<bindings xmlns='http://www.mozilla.org/xbl'><binding id='foo'><content><hbox xmlns='http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul'><children xmlns='http://www.mozilla.org/xbl'/></hbox></content></binding></bindings>\n") + '")';
+}
+
+]]>
+</script>
+
+<listbox style="float: right;"><listitem/><listitem id="b"/><listitem><hbox style="-moz-binding: url(#m);"/></listitem></listbox>
+
+</window>
diff --git a/layout/xul/crashtests/464407-1.xhtml b/layout/xul/crashtests/464407-1.xhtml
new file mode 100644
index 0000000000..83666a6a46
--- /dev/null
+++ b/layout/xul/crashtests/464407-1.xhtml
@@ -0,0 +1,9 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<head>
+</head>
+<body>
+
+<xul:radio style="overflow: auto; height: 72057594037927940pt; display: table-cell;"/>
+
+</body>
+</html>
diff --git a/layout/xul/crashtests/467080.xul b/layout/xul/crashtests/467080.xul
new file mode 100644
index 0000000000..bc579b0ee3
--- /dev/null
+++ b/layout/xul/crashtests/467080.xul
@@ -0,0 +1,24 @@
+<?xml-stylesheet href="chrome://browser/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" xmlns:html="http://www.w3.org/1999/xhtml" xmlns:mathml="http://www.w3.org/1998/Math/MathML" style="-moz-binding:url(#a);" class="reftest-wait">
+
+<content xmlns="http://www.mozilla.org/xbl" ordinal="-1">
+<mathml:median style="display: block;"/>
+</content>
+
+<script xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+function finish() {
+  document.documentElement.removeAttribute("class");
+}
+function doe() {
+document.documentElement.removeAttribute('style');
+setTimeout(finish, 0);
+}
+setTimeout(doe, 100);
+]]></script>
+
+
+<bindings xmlns="http://www.mozilla.org/xbl">
+<binding id="a">
+<content><children/></content>
+</binding></bindings>
+</window>
diff --git a/layout/xul/crashtests/467481-1.xul b/layout/xul/crashtests/467481-1.xul
new file mode 100644
index 0000000000..56fbd44413
--- /dev/null
+++ b/layout/xul/crashtests/467481-1.xul
@@ -0,0 +1,6 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="document.getElementById('a').setAttribute('ordinal', 30);">
+  <listbox>
+    <listitem id="a"/>
+    <listitem><iframe/></listitem>
+  </listbox>
+</window>
diff --git a/layout/xul/crashtests/470063-1.html b/layout/xul/crashtests/470063-1.html
new file mode 100644
index 0000000000..11c01b30e4
--- /dev/null
+++ b/layout/xul/crashtests/470063-1.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html>
+<head>
+<script type="text/javascript">
+
+function boom()
+{
+  document.removeChild(document.documentElement)
+  document.appendChild(document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "hbox"));
+}
+
+</script>
+</head>
+<body onload="boom();"></body>
+</html>
diff --git a/layout/xul/crashtests/470272.html b/layout/xul/crashtests/470272.html
new file mode 100644
index 0000000000..f23de269b9
--- /dev/null
+++ b/layout/xul/crashtests/470272.html
@@ -0,0 +1,21 @@
+<html>
+<head>
+<script>
+function doe2(i) {
+document.documentElement.offsetHeight;
+document.getElementById('a').setAttribute('style', 'display: -moz-inline-box;');
+document.documentElement.offsetHeight;
+}
+</script>
+</head>
+<body style="float: right; -moz-column-count: 2; height: 20%;" onload="setTimeout(doe2,0);">
+  <div style="display: none;"></div>
+  <ul style="display: -moz-inline-box;"></ul>
+  <span id="a">
+    <ul style="display: -moz-grid; overflow: scroll;"></ul>
+      <span style="display: -moz-inline-box; height: 10px;">
+        <span style="position: absolute;"></span>
+      </span>
+  </span>
+</body>
+</html>
diff --git a/layout/xul/crashtests/472189.xul b/layout/xul/crashtests/472189.xul
new file mode 100644
index 0000000000..e276d8fc70
--- /dev/null
+++ b/layout/xul/crashtests/472189.xul
@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window id="yourwindow" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<script type="text/javascript">
+<![CDATA[
+function onload() {
+  document.addEventListener("DOMAttrModified", function() {}, true);
+  document.getElementById("test").setAttribute("value", "50");
+}
+]]>
+</script>
+<progressmeter id="test"/>
+</window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/475133.html b/layout/xul/crashtests/475133.html
new file mode 100644
index 0000000000..ea4ee63250
--- /dev/null
+++ b/layout/xul/crashtests/475133.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<html>
+<head>
+<script type="text/javascript">
+function x()
+{
+  document.removeEventListener("DOMAttrModified", x, false);
+  document.removeChild(document.documentElement);
+}
+
+function boom()
+{
+  var p = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "progressmeter");
+  document.addEventListener("DOMAttrModified", x, false);
+  document.documentElement.appendChild(p);
+}
+</script>
+</head>
+<body onload="boom();"></body>
+</html>
diff --git a/layout/xul/crashtests/488210-1.xhtml b/layout/xul/crashtests/488210-1.xhtml
new file mode 100644
index 0000000000..9c8e2640c1
--- /dev/null
+++ b/layout/xul/crashtests/488210-1.xhtml
@@ -0,0 +1,19 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+<script type="text/javascript">
+
+function boom()
+{
+  var XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+  var listbox = document.createElementNS(XUL_NS, 'listbox');
+  document.body.appendChild(listbox);
+  listbox.appendChild(document.createElementNS(XUL_NS, 'listitem'));
+  listbox.appendChild(document.createElementNS(XUL_NS, 'listboxbody'));
+  listbox.appendChild(document.createElementNS(XUL_NS, 'hbox'));
+}
+
+</script>
+</head>
+
+<body onload="boom();"></body>
+</html>
diff --git a/layout/xul/crashtests/495728-1.xul b/layout/xul/crashtests/495728-1.xul
new file mode 100644
index 0000000000..ee8498d054
--- /dev/null
+++ b/layout/xul/crashtests/495728-1.xul
@@ -0,0 +1,239 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window id="list-testcase" title="Testcase"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        class="reftest-wait">
+
+<script>
+function scrollup() {
+  var list = document.getElementById('list');
+  var firstindex = list.getIndexOfItem(document.getElementById('first'));
+  list.ensureIndexIsVisible(firstindex);
+  setTimeout("document.documentElement.removeAttribute('class')",1);
+}
+
+function scrolldown() {
+  var list = document.getElementById('list');
+  var lastindex = list.getIndexOfItem(document.getElementById('last'));
+  list.ensureIndexIsVisible(lastindex);
+  setTimeout("scrollup()",1);
+}
+
+window.addEventListener("load", scrolldown, false);
+</script>
+		
+<listbox id="list">
+<listitem label="Item x" id="first"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x"/>
+<listitem label="Item x" id="last"/>
+</listbox>
+
+</window>
diff --git a/layout/xul/crashtests/508927-1.xul b/layout/xul/crashtests/508927-1.xul
new file mode 100644
index 0000000000..98faff4a6c
--- /dev/null
+++ b/layout/xul/crashtests/508927-1.xul
@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<bindings xmlns="http://www.mozilla.org/xbl"><binding id="foo"><content><xul:listrows xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"><xul:listboxbody/><children xmlns="http://www.mozilla.org/xbl"/></xul:listrows></content></binding></bindings>
+<hbox style="-moz-binding: url(#foo);"><listitem/><listitem/></hbox>
+</window>
diff --git a/layout/xul/crashtests/508927-2.xul b/layout/xul/crashtests/508927-2.xul
new file mode 100644
index 0000000000..5bf4f9a0c7
--- /dev/null
+++ b/layout/xul/crashtests/508927-2.xul
@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<bindings xmlns="http://www.mozilla.org/xbl"><binding id="foo"><content><xul:listrows xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"><xul:listboxbody/><children xmlns="http://www.mozilla.org/xbl"/></xul:listrows></content></binding></bindings>
+<hbox style="-moz-binding: url(#foo);"><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/><listitem/></hbox>
+</window>
diff --git a/layout/xul/crashtests/514300-1.xul b/layout/xul/crashtests/514300-1.xul
new file mode 100644
index 0000000000..d0d655011e
--- /dev/null
+++ b/layout/xul/crashtests/514300-1.xul
@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="document.getElementById('listbox').removeChild(document.getElementById('span'));">
+
+<bindings xmlns="http://www.mozilla.org/xbl">
+  <binding id="foo">
+    <content><listitem xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"><children xmlns="http://www.mozilla.org/xbl"/></listitem></content>
+  </binding>
+</bindings>
+
+<listbox id="listbox" style="-moz-binding: url(#foo)"><span xmlns="http://www.w3.org/1999/xhtml" id="span"/></listbox>
+
+</window>
diff --git a/layout/xul/crashtests/536931-1.xhtml b/layout/xul/crashtests/536931-1.xhtml
new file mode 100644
index 0000000000..6f3fc1396a
--- /dev/null
+++ b/layout/xul/crashtests/536931-1.xhtml
@@ -0,0 +1,4 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+<listbox id="listbox" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"><tab/></listbox>
+<script>window.addEventListener("load", function() { document.documentElement.appendChild(document.getElementById("listbox")); }, false);</script>
+</html>
diff --git a/layout/xul/crashtests/538308-1.xul b/layout/xul/crashtests/538308-1.xul
new file mode 100644
index 0000000000..a96f3fa4ed
--- /dev/null
+++ b/layout/xul/crashtests/538308-1.xul
@@ -0,0 +1,32 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        onload="run()">
+
+    <tree id="tr" flex="1">
+        <treecols>
+            <treecol/>
+        </treecols>
+        <treechildren>
+            <html:optgroup id="group">
+                <html:option id="victim" label="never see this"/>
+            </html:optgroup>
+        </treechildren>
+    </tree>
+
+    <script type="text/javascript"><![CDATA[
+    function run() {
+        group = document.getElementById("group");
+        tc = document.createElement("treechildren");
+        group.appendChild(tc);
+
+        v = document.getElementById("victim");
+        v.parentNode.removeChild(v);
+        v = null;
+
+        tree = document.getElementById("tr");
+        col = tree.columns[0];
+        alert(tree.view.getItemAtIndex(1, col)); 
+    }
+    ]]></script>
+</window>
diff --git a/layout/xul/crashtests/557174-1.xml b/layout/xul/crashtests/557174-1.xml
new file mode 100644
index 0000000000..02850a2db9
--- /dev/null
+++ b/layout/xul/crashtests/557174-1.xml
@@ -0,0 +1 @@
+<ther:window xmlns:ther="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" a="" e=""><HTML><ther:statusbar l="" c=""><ther:menulist d=""><ther:menu t="" i="" l=""><mat:h xmlns:mat="http://www.w3.org/1998/Math/MathML" w=""/></ther:menu><ther:menupopup p=""/><ther:menu a="" t="" l=""><ther:menuseparator u="" x=""><xht:html xmlns:xht="http://www.w3.org/1999/xhtml" x=""><xht:body d=""><xht:abbr d=""><xht:abbr p=""><xht:small s=""><xht:a s=""><xht:var e=""><xht:samp e=""><xht:code p=""><xht:b e=""><xht:b d=""><xht:del t=""><xht:h4 r=""><xht:var l=""><xht:i r=""><xht:em r=""><xht:em n=""><xht:map g=""><xht:isindex d=""/></xht:map></xht:em></xht:em></xht:i></xht:var></xht:h4></xht:del></xht:b></xht:b></xht:code></xht:samp></xht:var></xht:a></xht:small></xht:abbr></xht:abbr></xht:body></xht:html></ther:menuseparator></ther:menu></ther:menulist></ther:statusbar></HTML></ther:window>
\ No newline at end of file
diff --git a/layout/xul/crashtests/564705-1.xul b/layout/xul/crashtests/564705-1.xul
new file mode 100644
index 0000000000..b0f29bef7a
--- /dev/null
+++ b/layout/xul/crashtests/564705-1.xul
@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"><label value="&#x2026;" accesskey="b"></label></window>
+
diff --git a/layout/xul/crashtests/583957-1.html b/layout/xul/crashtests/583957-1.html
new file mode 100644
index 0000000000..85b51bf0c2
--- /dev/null
+++ b/layout/xul/crashtests/583957-1.html
@@ -0,0 +1,20 @@
+<html>
+<head>
+<script>
+
+function boom()
+{
+  window.addEventListener("DOMSubtreeModified", function(){}, false);
+
+  var m = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "menuitem");
+  document.body.appendChild(m);
+  m.setAttribute("type", "checkbox");
+  m.setAttribute("checked", "true");
+  m.removeAttribute("type");
+}
+
+</script>
+</head>
+
+<body onload="boom();"></body>
+</html>
diff --git a/layout/xul/crashtests/617089.html b/layout/xul/crashtests/617089.html
new file mode 100644
index 0000000000..22e5f6d535
--- /dev/null
+++ b/layout/xul/crashtests/617089.html
@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html>
+  <body>
+    <div style="display: -moz-inline-box;">
+      <table style="height: 101%;"><tbody><tr><td><div></div></td></tr></tbody></table>
+      <table style="height: 101%;"><tbody><tr><td><div></div></td></tr></tbody></table>
+    </div>
+  </body>
+</html>
diff --git a/layout/xul/crashtests/716503.html b/layout/xul/crashtests/716503.html
new file mode 100644
index 0000000000..250ad2ba40
--- /dev/null
+++ b/layout/xul/crashtests/716503.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html>
+<head>
+<style>
+div::before {
+  content: "j";
+  display:-moz-inline-box;
+}
+</style>
+<body><div></div></body>
+</html>
diff --git a/layout/xul/crashtests/crashtests.list b/layout/xul/crashtests/crashtests.list
new file mode 100644
index 0000000000..4ee6654c60
--- /dev/null
+++ b/layout/xul/crashtests/crashtests.list
@@ -0,0 +1,99 @@
+load 131008-1.xul
+load 137216-1.xul
+load 140218-1.xml
+load 151826-1.xul
+load 168724-1.xul
+load 189814-1.xul
+load 237787-1.xul
+load 265161-1.xul
+load 289410-1.xul
+load 290743.html
+load 291702-1.xul
+load 291702-2.xul
+load 291702-3.xul
+load 294371-1.xul
+load 311457-1.html
+load 321056-1.xhtml
+load 322786-1.xul
+load 325377.xul
+load 326834-1.html
+load 326879-1.xul
+load 327776-1.xul
+load 328135-1.xul
+load 329327-1.xul
+load 329407-1.xml
+load 329477-1.xhtml
+load 336962-1.xul
+load 344228-1.xul
+load 346083-1.xul
+load 346281-1.xul
+load 350460.xul
+load 360642-1.xul
+load 365151.xul
+load 366112-1.xul
+asserts(0-50) load 366203-1.xul # bug 1217984
+asserts(24) asserts-if(Android&&!asyncPan,9) load 367185-1.xhtml # bug 1220345
+load 369942-1.xhtml
+load 374102-1.xul
+load 376137-1.html
+load 376137-2.html
+load 377592-1.svg
+load 378961.html
+load 381862.html
+load 382746-1.xul
+load 382899-1.xul
+load 383236-1.xul
+load 384037-1.xhtml
+load 384105-1.html
+load 384373.html
+load 384491-1.xhtml
+load 384871-1.html
+load 386642.xul
+load 387033-1.xhtml
+load 387080-1.xul
+load 391974-1.html
+load 394120-1.xhtml
+load 397293.xhtml
+load 397304-1.html
+load 398326-1.xhtml
+load 399013.xul
+load 400779-1.xhtml
+load 402912-1.xhtml
+load 404192.xhtml
+load 407152.xul
+load 408904-1.xul
+load 412479-1.xhtml
+asserts(4) asserts-if(gtkWidget&&browserIsRemote,6) load 415394-1.xhtml # Bug 163838, bug 1195474
+load 417509.xul
+load 420424-1.xul
+load 430356-1.xhtml
+load 431738.xhtml
+load 432058-1.xul
+load 432068-1.xul
+load 432068-2.xul
+load 433296-1.xul
+load 433429.xul
+load 434458-1.xul
+load 452185.html
+load 460900-1.xul
+load 464149-1.xul
+asserts-if(winWidget,1) asserts-if(Android,0-1) load 464407-1.xhtml # Bug 450974 on win, Bug 1267054 on Android
+load 467080.xul
+load 467481-1.xul
+load 470063-1.html
+load 470272.html
+load 472189.xul
+load 475133.html
+load 488210-1.xhtml
+load 495728-1.xul
+load 508927-1.xul
+load 508927-2.xul
+load 514300-1.xul
+load 536931-1.xhtml
+asserts(1) load 538308-1.xul
+load 557174-1.xml
+load 564705-1.xul 
+load 583957-1.html
+load 617089.html
+load menulist-focused.xhtml
+load 716503.html
diff --git a/layout/xul/crashtests/menulist-focused.xhtml b/layout/xul/crashtests/menulist-focused.xhtml
new file mode 100644
index 0000000000..7a09a838d7
--- /dev/null
+++ b/layout/xul/crashtests/menulist-focused.xhtml
@@ -0,0 +1,5 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<body>
+<xul:menulist focused="true"/>
+</body>
+</html>
diff --git a/layout/xul/grid/crashtests/306911-crash.xul b/layout/xul/grid/crashtests/306911-crash.xul
new file mode 100644
index 0000000000..cf55dfdf87
--- /dev/null
+++ b/layout/xul/grid/crashtests/306911-crash.xul
@@ -0,0 +1,4 @@
+<?xml version="1.0"?>

<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>

<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

<listbox id="thelist" flex="1">
  <listitem label="Item1" value="item1">
+     <listitem label="Item2" value="item2"/>
+  </listitem>
</listbox>


+</window>
\ No newline at end of file
diff --git a/layout/xul/grid/crashtests/306911-grid-testcases.xul b/layout/xul/grid/crashtests/306911-grid-testcases.xul
new file mode 100644
index 0000000000..bb69f5bcd2
--- /dev/null
+++ b/layout/xul/grid/crashtests/306911-grid-testcases.xul
@@ -0,0 +1,99 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+	<tabbox>
+		<tabs>
+			<tab label="full grid" />
+			<tab label="grid alone" />
+			<tab label="columns alone" />
+			<tab label="rows alone" />
+			<tab label="column alone" />
+			<tab label="row alone" />
+			<tab label="wacky" />
+		</tabs>
+		<tabpanels>
+			<tabpanel>
+				<grid>
+					<rows style="color: blue">
+						<row>
+							<label value="row 1,1" />
+							<label value="row 1,2" />
+						</row>
+						<row>
+							<label value="row 2,1" />
+							<label value="row 2,2" />
+						</row>
+					</rows>
+					<columns style="color: fuchsia; opacity: 0.7">
+						<column>
+							<label value="column 1,1" />
+							<label value="column 1,2" />
+						</column>
+						<column>
+							<label value="column 2,1" />
+							<label value="column 2,2" />
+						</column>
+					</columns>
+				</grid>
+			</tabpanel>
+			<tabpanel>
+				<grid>
+					<label value="Text inside grid" />
+				</grid>
+			</tabpanel>
+			<tabpanel>
+				<columns>
+					<label value="Text inside columns" />
+				</columns>
+			</tabpanel>
+			<tabpanel>
+				<rows>
+					<label value="Text inside rows" />
+				</rows>
+			</tabpanel>
+			<tabpanel>
+				<column>
+					<label value="Text inside column" />
+				</column>
+			</tabpanel>
+			<tabpanel>
+				<row>
+					<label value="Text inside row" />
+				</row>
+			</tabpanel>
+			<tabpanel>
+				<grid>
+					<label value="Text inside grid one" />
+					<rows style="color: blue">
+                                                <label value="Text inside rows #1" />
+						<row>
+							<label value="row 1,1" />
+							<label value="row 1,2" />
+						</row>
+                                                <label value="Text inside rows #2" />
+						<row>
+							<label value="row 2,1" />
+							<label value="row 2,2" />
+						</row>
+                                                <label value="Text inside rows #3" />
+					</rows>
+					<label value="Text inside grid two" style="opacity: 0.7" />
+					<columns style="color: fuchsia; opacity: 0.7">
+                                                <label value="Text inside columns #1" />
+						<column>
+							<label value="column 1,1" />
+							<label value="column 1,2" />
+						</column>
+                                                <label value="Text inside columns #2" />
+						<column>
+							<label value="column 2,1" />
+							<label value="column 2,2" />
+						</column>
+                                                <label value="Text inside columns #3" />
+					</columns>
+					<label value="Text inside grid three" style="opacity: 0.4" />
+				</grid>
+			</tabpanel>
+		</tabpanels>
+	</tabbox>
+</window>
diff --git a/layout/xul/grid/crashtests/306911-grid-testcases2.xul b/layout/xul/grid/crashtests/306911-grid-testcases2.xul
new file mode 100644
index 0000000000..c6b4e3849e
--- /dev/null
+++ b/layout/xul/grid/crashtests/306911-grid-testcases2.xul
@@ -0,0 +1,98 @@
+<?xml version="1.0"?>
+<!-- vim:sw=4:ts=4:noet:
+  -->
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+	<tabbox>
+		<tabs>
+			<tab label="no group" />
+			<tab label="wacky orientations" />
+		</tabs>
+		<tabpanels>
+			<tabpanel>
+				<grid>
+					<row>
+						<label value="row 1,1" />
+						<label value="row 1,2" />
+					</row>
+					<row>
+						<label value="row 2,1" />
+						<label value="row 2,2" />
+					</row>
+					<column>
+						<label value="column 1,1" />
+						<label value="column 1,2" />
+					</column>
+					<column>
+						<label value="column 2,1" />
+						<label value="column 2,2" />
+					</column>
+				</grid>
+			</tabpanel>
+			<tabpanel>
+				<grid>
+					<rows style="color: green">
+						<row>
+							<label value="rows+row 1" />
+							<label value="rows+row 2" />
+						</row>
+						<column>
+							<label value="rows+column 1" />
+							<label value="rows+column 2" />
+						</column>
+						<rows style="color: purple">
+							<row>
+								<label value="rows+rows+row 1" />
+								<label value="rows+rows+row 2" />
+							</row>
+							<column>
+								<label value="rows+rows+column 1" />
+								<label value="rows+rows+column 2" />
+							</column>
+						</rows>
+						<columns style="color: blue">
+							<row>
+								<label value="rows+columns+row 1" />
+								<label value="rows+columns+row 2" />
+							</row>
+							<column>
+								<label value="rows+columns+column 1" />
+								<label value="rows+columns+column 2" />
+							</column>
+						</columns>
+					</rows>
+					<columns style="opacity: 0.7; color: lime">
+						<row>
+							<label value="columns+row 1" />
+							<label value="columns+row 2" />
+						</row>
+						<column>
+							<label value="columns+column 1" />
+							<label value="columns+column 2" />
+						</column>
+						<rows style="color: fuchsia">
+							<row>
+								<label value="columns+rows+row 1" />
+								<label value="columns+rows+row 2" />
+							</row>
+							<column>
+								<label value="columns+rows+column 1" />
+								<label value="columns+rows+column 2" />
+							</column>
+						</rows>
+						<columns style="color: aqua">
+							<row>
+								<label value="columns+columns+row 1" />
+								<label value="columns+columns+row 2" />
+							</row>
+							<column>
+								<label value="columns+columns+column 1" />
+								<label value="columns+columns+column 2" />
+							</column>
+						</columns>
+					</columns>
+				</grid>
+			</tabpanel>
+		</tabpanels>
+	</tabbox>
+</window>
diff --git a/layout/xul/grid/crashtests/311710-1.xul b/layout/xul/grid/crashtests/311710-1.xul
new file mode 100644
index 0000000000..403b267e96
--- /dev/null
+++ b/layout/xul/grid/crashtests/311710-1.xul
@@ -0,0 +1,22 @@
+<window title="Testcase bug 311710 - Evil xul testcase, using display:-moz-grid-group causes crash [@ nsGridRow::IsCollapsed]"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" 
+        xmlns:html="http://www.w3.org/1999/xhtml">
+<script type="application/x-javascript">
+function clickit() {
+  var button = document.getElementById('button');
+  var evt = document.createEvent("MouseEvents");
+  evt.initMouseEvent("click", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
+  button.dispatchEvent(evt);
+}
+window.addEventListener('load', clickit, false);
+</script>
+
+        <grid>
+          <rows>
+            <row>
+            <separator/> 
+            </row>
+          </rows>
+        </grid>
+<button id="button" onclick="document.getElementsByTagName('row')[0].style.display='-moz-grid-group'" label="Mozilla should not crash, when clicking this button"/>
+</window>
diff --git a/layout/xul/grid/crashtests/312784-1.xul b/layout/xul/grid/crashtests/312784-1.xul
new file mode 100644
index 0000000000..ee4054d800
--- /dev/null
+++ b/layout/xul/grid/crashtests/312784-1.xul
@@ -0,0 +1,29 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<script type="application/x-JavaScript">
+function crash() {
+  document.getElementById("test").style.display = "none";
+}
+
+function clickit() {
+  var button = document.getElementById('button');
+  var evt = document.createEvent("MouseEvents");
+  evt.initMouseEvent("click", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
+  button.dispatchEvent(evt);
+}
+
+window.onload = clickit;
+
+</script>
+
+        <grid>
+          <columns>
+            <column/>
+          </columns>
+          <rows id="test">
+	    <row><button label="placeholder"/></row>
+          </rows>
+        </grid>
+<button id="button" label="Crash me" onclick="crash()"/>
+</window>
diff --git a/layout/xul/grid/crashtests/313173-1-inner.xul b/layout/xul/grid/crashtests/313173-1-inner.xul
new file mode 100644
index 0000000000..284d6c1f1e
--- /dev/null
+++ b/layout/xul/grid/crashtests/313173-1-inner.xul
@@ -0,0 +1,41 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window title="Testcase bug - Crash with evil xul testcase, using -moz-grid/table-caption"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<grid flex="1">
+  <columns>
+    <column flex="1"/>
+  </columns>
+
+  <rows>
+    <row>
+    </row>
+  </rows>
+</grid>
+
+<html:script>
+function doe(){
+document.getElementsByTagName('columns')[0].style.display='table-caption';
+setTimeout(doe2,20);
+}
+function doe2(){
+document.getElementsByTagName('columns')[0].style.display='-moz-grid';
+}     
+
+function clickit() {
+  var button = document.getElementById('button');
+  var evt = document.createEvent("MouseEvents");
+  evt.initMouseEvent("click", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
+  button.dispatchEvent(evt);
+setTimeout('clickit();', 20);
+}
+window.addEventListener('load', clickit, false);
+
+</html:script>
+        <html:button id="button" onclick="doe()" label="click">Clicking this should not crash Mozilla</html:button>
+</window>
+
diff --git a/layout/xul/grid/crashtests/313173-1.html b/layout/xul/grid/crashtests/313173-1.html
new file mode 100644
index 0000000000..8b45339abb
--- /dev/null
+++ b/layout/xul/grid/crashtests/313173-1.html
@@ -0,0 +1,9 @@
+<html class="reftest-wait">
+<head>
+<script>
+setTimeout('document.documentElement.className = ""', 500);
+</script>
+<body>
+<iframe src="313173-1-inner.xul"></iframe>
+</body>
+</html>
diff --git a/layout/xul/grid/crashtests/321066-1.xul b/layout/xul/grid/crashtests/321066-1.xul
new file mode 100644
index 0000000000..789c2582c7
--- /dev/null
+++ b/layout/xul/grid/crashtests/321066-1.xul
@@ -0,0 +1,8 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <grid>
+    <rows>
+      <column/>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/crashtests/321073-1.xul b/layout/xul/grid/crashtests/321073-1.xul
new file mode 100644
index 0000000000..b92098b623
--- /dev/null
+++ b/layout/xul/grid/crashtests/321073-1.xul
@@ -0,0 +1,7 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <listcols>
+    <grid/>
+    <listitem/>
+  </listcols>
+</window>
\ No newline at end of file
diff --git a/layout/xul/grid/crashtests/382750-1.xul b/layout/xul/grid/crashtests/382750-1.xul
new file mode 100644
index 0000000000..7a9da73ec7
--- /dev/null
+++ b/layout/xul/grid/crashtests/382750-1.xul
@@ -0,0 +1,5 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<grid><rows><listbox/></rows></grid>
+
+</window>
diff --git a/layout/xul/grid/crashtests/400790-1.xul b/layout/xul/grid/crashtests/400790-1.xul
new file mode 100644
index 0000000000..4de7094286
--- /dev/null
+++ b/layout/xul/grid/crashtests/400790-1.xul
@@ -0,0 +1,20 @@
+<xul xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="boom();">
+
+<script>
+
+function boom()
+{
+  var XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+
+  var newListbox = document.createElementNS(XUL_NS, "listbox");
+  document.getElementById("listbox").appendChild(newListbox);
+
+  var newHbox = document.createElementNS(XUL_NS, "hbox");
+  document.getElementById("listitem").appendChild(newHbox);
+}
+
+</script>
+
+<listbox id="listbox"><listitem id="listitem" /></listbox>
+
+</xul>
diff --git a/layout/xul/grid/crashtests/423802-crash.xul b/layout/xul/grid/crashtests/423802-crash.xul
new file mode 100644
index 0000000000..0ae4eab8f0
--- /dev/null
+++ b/layout/xul/grid/crashtests/423802-crash.xul
@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+
+<window xmlns  = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<grid>
+  <columns>
+    <column id="col1" flex="1"/>
+  <column id="col2" flex="1"/>
+    <column id="col3" flex="P-2"/>
+  </columns>
+</grid>
+
+</window>
diff --git a/layout/xul/grid/crashtests/crashtests.list b/layout/xul/grid/crashtests/crashtests.list
new file mode 100644
index 0000000000..afe8e10027
--- /dev/null
+++ b/layout/xul/grid/crashtests/crashtests.list
@@ -0,0 +1,11 @@
+load 306911-crash.xul
+load 306911-grid-testcases.xul
+load 306911-grid-testcases2.xul
+load 311710-1.xul
+load 312784-1.xul
+load 313173-1.html
+load 321066-1.xul
+load 321073-1.xul
+load 382750-1.xul
+load 400790-1.xul
+load 423802-crash.xul
diff --git a/layout/xul/grid/examples/borderedcolumns.xul b/layout/xul/grid/examples/borderedcolumns.xul
new file mode 100644
index 0000000000..15ee069114
--- /dev/null
+++ b/layout/xul/grid/examples/borderedcolumns.xul
@@ -0,0 +1,43 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox>
+    <grid style="border: 2px inset gray;" id="grid">
+	   <columns>
+  	      <column style="border: 10px inset red;"/>
+  	      <column/>
+  	      <column style="border: 10px inset red;"/>
+       </columns>
+
+       <rows style="font-size: 20pt;">
+	     <row>
+		   <text value="Cell 1 "/>
+		   <text value="Cell 2 "/>
+		   <text value="Cell 3 "/>
+		 </row>
+	     <row>
+		   <text value="Cell 4 "/>
+		   <text value="Cell 5 " style="border: 10px inset red;"/>
+		   <text value="Cell 6 "/>
+		 </row>
+	     <row>
+		   <text value="Cell 7 "/>
+		   <text value="Cell 8 "/>
+		   <text value="Cell 9 "/>
+		 </row>
+
+	   </rows>
+	</grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/examples/borderedrowscolumns.xul b/layout/xul/grid/examples/borderedrowscolumns.xul
new file mode 100644
index 0000000000..94d3d8d998
--- /dev/null
+++ b/layout/xul/grid/examples/borderedrowscolumns.xul
@@ -0,0 +1,55 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox>
+    <grid style="border: 2px inset gray;" id="grid">
+	   <columns style="border: 0px solid blue">
+  	      <column/>
+  	      <column/>
+  	      <column/>
+       </columns>
+
+       <rows style="font-size: 40pt; border: 15px inset blue">
+	     <row>
+		   <text value="Cell(1)"/>
+		   <text value="Cell(2)"/>
+		   <text value="Cell(3)"/>
+		 </row>
+		   <rows style="border: 10px inset green">
+			 <row>
+			   <text value="Cell(1)"/>
+			   <text value="Cell(2)"/>
+			   <text value="Cell(3)"/>
+			 </row>
+			 <row>
+			   <text value="Cell(4)"/>
+			   <text value="Cell(5)"/>
+			   <text value="Cell(6)"/>
+			 </row>
+			 <row>
+			   <text value="Cell(7)"/>
+			   <text value="Cell(8)"/>
+			   <text value="Cell(9)"/>
+			 </row>
+
+		   </rows>	     
+	     <row>
+		   <text value="Cell(7)"/>
+		   <text value="Cell(8)"/>
+		   <text value="Cell(9)"/>
+		 </row>
+	   </rows>
+	</grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/examples/borderedrowscolumns2.xul b/layout/xul/grid/examples/borderedrowscolumns2.xul
new file mode 100644
index 0000000000..96b6ca9e5a
--- /dev/null
+++ b/layout/xul/grid/examples/borderedrowscolumns2.xul
@@ -0,0 +1,44 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+<?xml-stylesheet href="gridsample.css" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox>
+    <grid style="border: 2px inset gray;" id="grid">
+	   <columns>
+  	      <column style="border: 10px solid red;"/>
+  	      <column/>
+  	      <column/>
+       </columns>
+
+       <rows style="font-size: 40pt;">
+	     <row style="border: 10px solid red;">
+		   <text value="Cell 1 "/>
+		   <text value="Cell 2 "/>
+		   <text value="Cell 3 "/>
+		 </row>
+	     <row>
+		   <text value="Cell 4 "/>
+		   <text value="Cell 5 "/>
+		   <text value="Cell 6 "/>
+		 </row>
+	     <row>
+		   <text value="Cell 7 "/>
+		   <text value="Cell 8 "/>
+		   <text value="Cell 9 "/>
+		 </row>
+
+	   </rows>
+	</grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/examples/borderedrowscolumns3.xul b/layout/xul/grid/examples/borderedrowscolumns3.xul
new file mode 100644
index 0000000000..30a6fcc1be
--- /dev/null
+++ b/layout/xul/grid/examples/borderedrowscolumns3.xul
@@ -0,0 +1,57 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox>
+    <grid style="border: 2px inset gray;" id="grid">
+	   <columns>
+  	      <column/>
+  	      <columns style="border: 10px solid red">
+  	         <column/>
+		  </columns>
+  	      <column/>
+       </columns>
+
+       <rows style="font-size: 24pt">
+	     <row>
+		   <text value="Cell(1)"/>
+		   <text value="Cell(2)"/>
+		   <text value="Cell(3)"/>
+		 </row>
+		   <rows style="border: 10px solid green">
+			 <row>
+			   <text value="Cell(1)"/>
+			   <text value="Cell(2)"/>
+			   <text value="Cell(3)"/>
+			 </row>
+			 <row>
+			   <text value="Cell(4)"/>
+			   <text value="Cell(5)"/>
+			   <text value="Cell(6)"/>
+			 </row>
+			 <row>
+			   <text value="Cell(7)"/>
+			   <text value="Cell(8)"/>
+			   <text value="Cell(9)"/>
+			 </row>
+
+		   </rows>	     
+	     <row>
+		   <text value="Cell(7)"/>
+		   <text value="Cell(8)"/>
+		   <text value="Cell(9)"/>
+		 </row>
+	   </rows>
+	</grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/examples/bordermargincolumns1.xul b/layout/xul/grid/examples/bordermargincolumns1.xul
new file mode 100644
index 0000000000..009f932a8c
--- /dev/null
+++ b/layout/xul/grid/examples/bordermargincolumns1.xul
@@ -0,0 +1,44 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+<?xml-stylesheet href="gridsample.css" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox>
+    <grid style="border: 2px inset gray;" id="grid">
+	   <columns>
+  	      <column style="border: 10px inset red; margin: 10px; "/>
+  	      <column/>
+  	      <column/>
+       </columns>
+
+       <rows style="font-size: 40pt;">
+	     <row style="border: 5px solid green">
+		   <text value="Cell 1"/>
+		   <text value="Cell 2"/>
+		   <text value="Cell 3"/>
+		 </row>
+	     <row>
+		   <text value="Cell 4"/>
+		   <text value="Cell 5"/>
+		   <text value="Cell 6"/>
+		 </row>
+	     <row>
+		   <text value="Cell 7"/>
+		   <text value="Cell 8"/>
+		   <text value="Cell 9"/>
+		 </row>
+
+	   </rows>
+	</grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/examples/collapsetest.xul b/layout/xul/grid/examples/collapsetest.xul
new file mode 100644
index 0000000000..5e1a042f61
--- /dev/null
+++ b/layout/xul/grid/examples/collapsetest.xul
@@ -0,0 +1,67 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical" style="border: 2px solid green"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+<script>
+
+   function collapseTag(id)
+   {
+     var row = window.document.getElementById(id);
+	 row.setAttribute("collapsed","true");
+   }
+
+   function uncollapseTag(id)
+   {
+     var row = window.document.getElementById(id);
+	 row.setAttribute("collapsed","false");
+   }
+
+
+</script>
+
+    <hbox>
+		<grid style="border: 2px solid red;" id="grid">
+		   <columns id="columns1">
+		      <column id="column1"/>
+		      <column id="column2"/>
+		      <column id="column3"/>
+		   </columns>
+
+		   <rows id="rows1" style="font-size: 24pt">
+			 <row id="row1">
+			    <text value="cell1"/>
+			    <text value="cell2"/>
+			    <text value="cell3"/>
+			 </row>
+ 			 <row id="row2">
+			    <text value="cell4"/>
+			    <text value="cell5"/>
+			    <text value="cell6"/>
+			 </row>
+			 <row id="row3">
+			    <text value="cell7"/>
+			    <text value="cell8"/>
+			    <text value="cell9"/>
+			 </row>
+		   </rows>
+		</grid>
+    </hbox>
+	<hbox>
+	  <button label="collapse row 2"   oncommand="collapseTag('row2');"/>
+	  <button label="uncollapse row 2" oncommand="uncollapseTag('row2');"/>
+ 	  <button label="collapse column 2"   oncommand="collapseTag('column2');"/>
+	  <button label="uncollapse column 2" oncommand="uncollapseTag('column2');"/>
+
+	</hbox>
+
+</window>
diff --git a/layout/xul/grid/examples/divcolumngrid.xul b/layout/xul/grid/examples/divcolumngrid.xul
new file mode 100644
index 0000000000..2268c302cb
--- /dev/null
+++ b/layout/xul/grid/examples/divcolumngrid.xul
@@ -0,0 +1,33 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical" style="border: 2px solid green"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+  <hbox>
+    <grid style="border: 2px solid red;">
+	   <columns>
+          <column/>
+		  <description style="border: 10px inset gray">
+		    hello
+		  </description>
+		  <column/>
+	   </columns>
+     
+	   <rows>
+	     <row>
+			 <text style="font-size: 40px" value="foo1"/>
+			 <text style="font-size: 40px" value="foo2"/>
+		 </row>
+	   </rows>
+	</grid>
+	<spacer flex="1" style="background-color: white"/>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/examples/divrowgrid.xul b/layout/xul/grid/examples/divrowgrid.xul
new file mode 100644
index 0000000000..657553aab3
--- /dev/null
+++ b/layout/xul/grid/examples/divrowgrid.xul
@@ -0,0 +1,36 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical" style="border: 2px solid green"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox>
+    <grid style="width: 100px; border: 2px solid red;">     
+	   <rows>
+	     <row style="font-size: 40px">
+			 <text value="foo1"/>
+			 <text value="foo2"/>
+		 </row>
+		<description>
+			this is some html in the row this should wrap if it is big enough.
+		</description>
+	     <row style="font-size: 40px">
+			 <text value="foo3"/>
+			 <text value="foo4"/>
+		 </row>
+
+	   </rows>
+	</grid>
+	<spacer flex="1" style="background-color: white"/>
+  </hbox>
+
+
+</window>
diff --git a/layout/xul/grid/examples/dynamicgrid.xul b/layout/xul/grid/examples/dynamicgrid.xul
new file mode 100644
index 0000000000..d718df5f91
--- /dev/null
+++ b/layout/xul/grid/examples/dynamicgrid.xul
@@ -0,0 +1,370 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+<?xml-stylesheet href="gridsample.css" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical" 
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+		onload="start()"> 
+
+<script>
+
+   var selected;
+   var count = 0;
+
+   function isCell(box)
+   {
+     if (box.localName == "row" || 
+	     box.localName == "column" ||
+		 box.localName == "rows" ||
+		 box.localName == "columns" ||
+		 box.localName == "grid")
+		 return false;
+
+	 return true;
+   }
+
+   function start()
+   {
+      selectIt(window.document.getElementById("rows"));
+   }
+
+   function selectIt(box)
+   {
+     if (!box)
+	   return;
+
+     var a = box.getAttribute("selected");
+	 if (a != "true") {
+	   box.setAttribute("selected","true");
+  	   if (selected)
+	      selected.setAttribute("selected","false");
+
+	   selected = box;
+     }
+   }
+
+   function addCellSelectionHandle(box)
+   {
+	 box.setAttribute("oncommand", "selectIt(this);");
+   }
+
+   function addRowColumnSelectionHandle(box)
+   {
+	 box.setAttribute("onclick", "selectIt(this);");
+   }
+
+   function createButton(str)
+   {
+	 var b = document.createElement("button");
+	 b.setAttribute("label", str+count);
+	 count++;
+	 addCellSelectionHandle(b);
+	 return b;
+   }
+
+   function createRow()
+   {
+	 var b = document.createElement("row");
+ 	 b.setAttribute("dynamic","true");
+
+	 addRowColumnSelectionHandle(b);
+	 return b;
+   }
+
+   function createColumn()
+   {
+	 var b = document.createElement("column");
+	 b.setAttribute("dynamic","true");
+	 addRowColumnSelectionHandle(b);
+	 return b;
+   }
+
+   function createText(str)
+   {
+	 var text = document.createElement("text");
+	 text.setAttribute("value", str+count);
+	 count++;
+	 text.setAttribute("style", "font-size: 40pt");
+	 addCellSelectionHandle(text);
+	 return text;
+   }
+
+   function appendElement(element, prepend)
+   {
+     if (!selected)
+	    return;
+
+     setUserAttribute(element);
+
+	 if (selected.localName == "rows") 
+	   appendRow(false);
+     else if (selected.localName == "columns")
+	   appendColumn(false);
+
+	 if (selected.localName == "row" || selected.localName == "column" ) { // is row or column
+		 selected.appendChild(element); 
+	 } else {
+		  var parent = selected.parentNode;
+		  if (prepend)
+		    parent.insertBefore(element, selected);	 
+		  else {
+		    var next = selected.nextSibling;
+			if (next)
+		      parent.insertBefore(element,next);
+			else
+			  parent.appendChild(element);
+		  }
+	 }
+     
+	 selectIt(element);
+   }
+
+   function getRows(box)
+   {
+      return window.document.getElementById("rows");
+   }
+
+   function getColumns(box)
+   {
+      return window.document.getElementById("columns");
+   }
+
+   function setUserAttribute(element)
+   {
+   	 var attributeBox = document.getElementById("attributebox");
+	 var valueBox = document.getElementById("valuebox");
+	 var attribute = attributeBox.value;
+	 var value = valueBox.value;
+	 if (attribute != "")
+	   element.setAttribute(attribute,value);
+   }
+
+   function appendRowColumn(rowColumn, prepend)
+   {
+     if (!selected)
+	    return;
+
+     setUserAttribute(rowColumn); 
+
+     var row = rowColumn;
+
+	 // first see what we are adding.
+
+	 if (isCell(selected)) { // if cell then select row/column
+	   selectIt(selected.parentNode);
+	 }
+
+	 if (selected.localName == "row" || selected.localName == "rows")
+	   if (row.localName == "column") {
+	     selectIt(getColumns(selected)); 
+		 dump("Selecting the column")
+		 dump("Selected="+selected.localName);
+		 }
+
+	 if (selected.localName == "column" || selected.localName == "columns")
+	   if (row.localName == "row")
+	     selectIt(getRows(selected));
+
+	 if (selected.localName == "rows" || selected.localName == "columns" ) 
+	 { // if rows its easy
+		 selected.appendChild(row); 
+	 } else {
+		  var parent = selected.parentNode;
+		  if (prepend)
+		    parent.insertBefore(row, selected);	 
+		  else {
+		    var next = selected.nextSibling;
+			if (next)
+		      parent.insertBefore(row,next);
+			else
+			  parent.appendChild(row);
+		  }
+	 }
+
+     selectIt(row);
+   }
+
+ function appendRow(prepend)
+ {
+   var row = createRow();
+   appendRowColumn(row,prepend);
+ }
+
+
+ function appendColumn(prepend)
+ {
+   var column = createColumn();
+   appendRowColumn(column,prepend);
+ }
+
+
+ function selectRows()
+ {
+    var rows = getRows();
+	if (rows.firstChild)
+      selectIt(rows.firstChild);
+	else
+	  selectIt(rows);
+ }
+
+
+ function selectColumns()
+ {
+    var columns = getColumns();
+	if (columns.firstChild)
+      selectIt(columns.firstChild);
+	else
+	  selectIt(columns);
+ }
+
+ function nextElement()
+ {
+   if (!selected)
+     return;
+
+   selectIt(selected.nextSibling);
+ }
+
+ function previousElement()
+ {
+   if (!selected)
+     return;
+
+   selectIt(selected.previousSibling);
+ }
+
+ function selectRow()
+ {
+   if (!selected)
+     return;
+
+   if (selected.localName == "row")
+     return;
+
+   if (isCell(selected)) {
+     if (selected.parentNode.localName == "row")
+       selectIt(selected.parentNode);
+   }
+ }
+
+ function selectColumn()
+ {
+   if (!selected)
+     return;
+
+   if (selected.localName == "column")
+     return;
+
+   if (isCell(selected)) {
+     if (selected.parentNode.localName == "column")
+       selectIt(selected.parentNode);
+   }
+ }
+
+ function collapseGrid()
+ {
+	 var grid = document.getElementById("grid");
+	 var collapsed = grid.getAttribute("collapsed");
+
+	 if (collapsed == "")
+	   grid.setAttribute("collapsed","true");
+	 else
+   	   grid.setAttribute("collapsed","");
+
+ }
+
+ function collapseElement()
+ {
+   if (selected) {
+	 var collapsed = selected.getAttribute("collapsed");
+
+	 if (collapsed == "")
+	   selected.setAttribute("collapsed","true");
+	 else
+   	   selected.setAttribute("collapsed","");
+	}
+ }
+
+</script>
+
+    <hbox flex="1" style="border: 2px inset gray; overflow: auto">
+	 <vbox flex="1">
+	  <hbox>
+		<grid id="grid" style="border: 2px solid red;">
+		   <columns id="columns">
+		   </columns>
+
+		   <rows start="true" id="rows">
+		   </rows>
+		</grid>
+	    <spacer flex="1"/>
+      </hbox>
+ 	    <spacer flex="1"/>
+	 </vbox>
+    </hbox>
+
+    <grid style="background-color: blue">
+	   <columns>
+             <column flex="1"/> 
+             <column flex="1"/>
+             <column flex="1"/>             
+             <column flex="1"/>
+ 	   </columns>
+	 <rows>
+     
+         <row>
+		  <button label="append row" oncommand="appendRow(false);"/>
+		  <button label="prepend row" oncommand="appendRow(true);"/>
+
+		  <button label="append column" oncommand="appendColumn(false);"/>
+		  <button label="prepend column" oncommand="appendColumn(true);"/>
+		 </row>
+
+        <row>
+
+		 <button label="append button" oncommand="appendElement(createButton('button'),false);"/>
+		 <button label="prepend button" oncommand="appendElement(createButton('button'),true);"/>
+
+		 <button label="append text" oncommand="appendElement(createText('text'),false);"/>
+		 <button label="prepend text" oncommand="appendElement(createText('text'),true);"/>
+
+        </row>
+
+		 <row>
+
+ 	     <button label="select rows" oncommand="selectRows()"/>
+	     <button label="select columns" oncommand="selectColumns()"/>
+
+		 <button label="next" oncommand="nextElement()"/>
+		 <button label="previous" oncommand="previousElement()"/>
+
+        </row>
+
+	<hbox align="center">
+ 	     <button label="collapse/uncollapse grid" flex="1" oncommand="collapseGrid()"/>
+ 	     <button label="collapse/uncollapse element" flex="1" oncommand="collapseElement()"/>
+        </hbox>
+
+
+
+	<hbox>
+
+         <text value="attribute"/>
+		 <textbox id="attributebox" value="" flex="1"/>
+         <text value="value"/>
+		 <textbox id="valuebox" value="" flex="2"/>
+        </hbox>
+
+
+       </rows>
+	</grid>
+
+</window>
diff --git a/layout/xul/grid/examples/flexgroupgrid.xul b/layout/xul/grid/examples/flexgroupgrid.xul
new file mode 100644
index 0000000000..f4cd6622cd
--- /dev/null
+++ b/layout/xul/grid/examples/flexgroupgrid.xul
@@ -0,0 +1,47 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+<?xml-stylesheet href="gridsample.css" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+   <hbox>
+      <grid style="border: 2px inset gray;" flex="1">
+         <columns>
+            <columns style="border: 10px solid red" flex="1">
+            <column flex="2"/>
+            <column flex="1"/>
+            </columns>
+            <column flex="1"/>
+         </columns>
+
+         <rows style="font-size: 20pt">
+            <rows>
+               <row>
+                  <text class="yellow" value="CellA"/>
+                  <text class="yellow" value="CellAB"/>
+                  <text class="yellow" value="CellABC"/>
+               </row>
+               <row>
+                  <text class="yellow" value="CellA"/>
+                  <text class="yellow" value="CellAB"/>
+                  <text class="yellow" value="CellABC"/>
+               </row>
+            </rows>
+            <row>
+               <text class="yellow" value="CellA"/>
+               <text class="yellow" value="CellAB"/>
+               <text class="yellow" value="CellABC"/>
+            </row>  
+         </rows>
+      </grid>
+   </hbox>
+</window>
diff --git a/layout/xul/grid/examples/javascriptappend.xul b/layout/xul/grid/examples/javascriptappend.xul
new file mode 100644
index 0000000000..f2a415cae2
--- /dev/null
+++ b/layout/xul/grid/examples/javascriptappend.xul
@@ -0,0 +1,42 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical" style="border: 2px solid green"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <script>
+    function start()
+	{
+	   var row = document.getElementById("row");
+	   var text = document.createElement("text");
+	   text.setAttribute("value", "foo");
+	   row.appendChild(text);
+	}
+
+  </script>
+
+  <hbox>
+    <grid style="border: 2px solid red;" id="grid">
+	   <columns>
+	   </columns>
+
+	   <rows>
+	     <row id="row">
+		   <button label="value"/>
+		 </row>
+	   </rows>
+	</grid>
+	<spacer flex="1" style="background-color: white"/>
+  </hbox>
+
+  <button label="insert" oncommand="start()"/>
+
+</window>
diff --git a/layout/xul/grid/examples/jumpygrid.xul b/layout/xul/grid/examples/jumpygrid.xul
new file mode 100644
index 0000000000..8bbeb5806a
--- /dev/null
+++ b/layout/xul/grid/examples/jumpygrid.xul
@@ -0,0 +1,82 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+<?xml-stylesheet href="gridsample.css" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical" style="border: 2px solid green"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+    <script>
+	  function flip(child)
+	  {
+	    var jump = child.getAttribute("jumpy");
+		if (jump != "true")
+		  child.setAttribute("jumpy","true");
+		else
+ 		  child.setAttribute("jumpy","false");
+	  }
+
+	</script>
+    <hbox>
+		<grid style="border: 2px solid yellow;">
+		   <columns>
+		   </columns>
+
+		   <rows>
+			 <row>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			 </row>
+			 <row>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			 </row>
+			 <row>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			 </row>
+			 <row>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			 </row>
+			 <row>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			 </row>
+			 <row>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			   <button label="button" class="jumpy"/>
+			 </row>
+
+		   </rows>
+		</grid>
+		<spacer style="border: 2px solid white;" flex="1"/>
+    </hbox>
+	<spacer style="border: 2px solid white;" flex="1"/>
+
+</window>
diff --git a/layout/xul/grid/examples/nestedrows.xul b/layout/xul/grid/examples/nestedrows.xul
new file mode 100644
index 0000000000..700f785b39
--- /dev/null
+++ b/layout/xul/grid/examples/nestedrows.xul
@@ -0,0 +1,48 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox flex="1">
+    <grid style="border: 2px solid red" flex="1">
+
+     <columns>
+        <column flex="1"/>
+        <column flex="1"/>
+        <column flex="1"/>
+     </columns>
+
+       <rows>
+         <row>
+	   		  <text  value="out1"/>
+	   		  <text  value="out2"/>
+	   		  <text  value="out3"/>
+         </row>
+
+         <rows flex="1" style="border: 10px inset yellow; font-size: 20pt">
+           <row>
+	   	  	  <text  value="in1"/>
+	   	  	  <text  value="in2"/>
+	   	  	  <text  value="in3"/>
+	       </row>
+           <row>
+	   	  	  <text  value="in4"/>
+	   	  	  <text  value="in5"/>
+	   	  	  <text  value="in5"/>
+	       </row>
+	     </rows>
+
+	 </rows>
+
+	</grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/examples/rowspan.xul b/layout/xul/grid/examples/rowspan.xul
new file mode 100644
index 0000000000..266a32229f
--- /dev/null
+++ b/layout/xul/grid/examples/rowspan.xul
@@ -0,0 +1,41 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical" style="border: 2px solid green"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox>
+    <grid style="border: 2px solid red;">
+	   <columns>
+         <column/>
+         <column/>
+	   </columns>
+     
+	   <rows>
+	     <row style="font-size: 40px">
+			 <text value="foo1"/>
+			 <text value="foo2"/>
+		 </row>
+		<box width="50" style="border:5px inset grey">
+			<text value="hello there. This spans"/>
+		</box>
+	     <row style="font-size: 40px" >
+			 <text value="foo1"/>
+			 <text value="foo2"/>
+		 </row>
+
+	   </rows>
+	</grid>
+	<spacer flex="1" style="background-color: white"/>
+  </hbox>
+
+
+</window>
diff --git a/layout/xul/grid/examples/scrollingcolumns.xul b/layout/xul/grid/examples/scrollingcolumns.xul
new file mode 100644
index 0000000000..f299096248
--- /dev/null
+++ b/layout/xul/grid/examples/scrollingcolumns.xul
@@ -0,0 +1,80 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox flex="1">
+    <grid style="border: 2px solid red" flex="1">
+
+       <rows>
+				<row flex="1"/>
+				<row flex="1"/>
+				<row flex="1"/>
+           </rows>
+       <columns>
+
+		   <column>
+	   		  <button label="left"/>
+	   		  <button label="left"/>
+	   		  <button label="left"/>
+   		   </column>
+
+         <columns flex="1" style="min-width: 1px; overflow: auto; background-color: green">
+           <column>
+	   	  	  <button label="cell1"/>
+	   	  	  <button label="cell1"/>
+	   	  	  <button label="cell1"/>
+	       </column>
+           <column>
+	   	  	  <button label="cell2"/>
+	   	  	  <button label="cell2"/>
+	   	  	  <button label="cell2"/>
+	       </column>
+           <column>
+	   	  	  <button label="cell3"/>
+	   	  	  <button label="cell3"/>
+	   	  	  <button label="cell3"/>
+	       </column>
+           <column>
+	   	  	  <button label="cell4"/>
+	   	  	  <button label="cell4"/>
+	   	  	  <button label="cell4"/>
+	       </column>
+           <column>
+	   	  	  <button label="cell5"/>
+	   	  	  <button label="cell5"/>
+	   	  	  <button label="cell5"/>
+	       </column>
+           <column>
+	   	  	  <button label="cell6"/>
+	   	  	  <button label="cell6"/>
+	   	  	  <button label="cell6"/>
+	       </column>
+           <column>
+	   	  	  <button label="cell7"/>
+	   	  	  <button label="cell7"/>
+	   	  	  <button label="cell7"/>
+	       </column>
+	   </columns>
+  		   <column>
+	   		  <button label="right"/>
+	   		  <button label="right"/>
+	   		  <button label="right"/>
+   		   </column>
+
+	 </columns>
+
+	</grid>
+	<spacer width="100"/>
+  </hbox>
+  <spacer height="100"/>
+</window>
diff --git a/layout/xul/grid/examples/scrollingrows.xul b/layout/xul/grid/examples/scrollingrows.xul
new file mode 100644
index 0000000000..fd5077cde3
--- /dev/null
+++ b/layout/xul/grid/examples/scrollingrows.xul
@@ -0,0 +1,80 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox flex="1">
+    <grid style="border: 2px solid red" flex="1">
+
+     <columns>
+        <column flex="1"/>
+        <column flex="1"/>
+        <column flex="1"/>
+     </columns>
+
+       <rows>
+		   <row>
+	   		  <button label="left"/>
+	   		  <button label="left"/>
+	   		  <button label="left"/>
+   		   </row>
+
+         <rows flex="1" style="border: 10px inset gray; overflow: auto; background-color: green">
+           <row>
+	   	  	  <button label="cell1"/>
+	   	  	  <button label="cell1"/>
+	   	  	  <button label="cell1"/>
+	       </row>
+           <row>
+	   	  	  <button label="cell2"/>
+	   	  	  <button label="cell2"/>
+	   	  	  <button label="cell2"/>
+	       </row>
+           <row>
+	   	  	  <button label="cell3"/>
+	   	  	  <button label="cell3"/>
+	   	  	  <button label="cell3"/>
+	       </row>
+           <row>
+	   	  	  <button label="cell4"/>
+	   	  	  <button label="cell4"/>
+	   	  	  <button label="cell4"/>
+	       </row>
+           <row>
+	   	  	  <button label="cell5"/>
+	   	  	  <button label="cell5"/>
+	   	  	  <button label="cell5"/>
+	       </row>
+           <row>
+	   	  	  <button label="cell6"/>
+	   	  	  <button label="cell6"/>
+	   	  	  <button label="cell6"/>
+	       </row>
+           <row>
+	   	  	  <button label="cell7"/>
+	   	  	  <button label="cell7"/>
+	   	  	  <button label="cell7"/>
+	       </row>
+	   </rows>
+  		   <row>
+	   		  <button label="right"/>
+	   		  <button label="right"/>
+	   		  <button label="right"/>
+   		   </row>
+
+	 </rows>
+
+	</grid>
+	<spacer width="100"/>
+  </hbox>
+  <spacer height="100"/>
+</window>
diff --git a/layout/xul/grid/examples/splitter.xul b/layout/xul/grid/examples/splitter.xul
new file mode 100644
index 0000000000..67946d4874
--- /dev/null
+++ b/layout/xul/grid/examples/splitter.xul
@@ -0,0 +1,40 @@
+<?xml version="1.0"?> 
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?> 
+
+<!DOCTYPE window> 
+
+
+<window orient="vertical" style="border: 2px solid green"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> 
+
+  <hbox>
+    <grid style="border: 2px solid red;">
+	   <columns>
+         <column style="min-width: 1px"/>
+         <splitter/>
+         <column style="min-width: 1px"/>
+	   </columns>
+     
+	   <rows>
+	     <row>
+			 <text style="font-size: 40px" value="foo1"/>
+			 <text style="font-size: 40px" value="foo2"/>
+		 </row>
+		 <label value="this is some text. This is longer"/>
+	     <row>
+    		 <text style="font-size: 40px" value="foo1"/>
+			 <text style="font-size: 40px" value="foo2"/>
+		 </row>
+
+	   </rows>
+	</grid>
+	<spacer flex="1" style="background-color: white"/>
+  </hbox>
+
+
+</window>
diff --git a/layout/xul/grid/moz.build b/layout/xul/grid/moz.build
new file mode 100644
index 0000000000..074985aafb
--- /dev/null
+++ b/layout/xul/grid/moz.build
@@ -0,0 +1,43 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+with Files('**'):
+    BUG_COMPONENT = ('Core', 'XP Toolkit/Widgets: XUL')
+
+EXPORTS += [
+    'nsGrid.h',
+    'nsGridCell.h',
+    'nsGridLayout2.h',
+    'nsGridRow.h',
+    'nsGridRowGroupLayout.h',
+    'nsGridRowLayout.h',
+    'nsGridRowLeafFrame.h',
+    'nsGridRowLeafLayout.h',
+    'nsIGridPart.h',
+]
+
+UNIFIED_SOURCES += [
+    'nsGrid.cpp',
+    'nsGridCell.cpp',
+    'nsGridLayout2.cpp',
+    'nsGridRow.cpp',
+    'nsGridRowGroupFrame.cpp',
+    'nsGridRowGroupLayout.cpp',
+    'nsGridRowLayout.cpp',
+    'nsGridRowLeafFrame.cpp',
+    'nsGridRowLeafLayout.cpp',
+]
+
+FINAL_LIBRARY = 'xul'
+LOCAL_INCLUDES += [
+    '..',
+    '../../forms',
+    '../../generic',
+    '../../style',
+]
+
+if CONFIG['GNU_CXX']:
+    CXXFLAGS += ['-Wno-error=shadow']
diff --git a/layout/xul/grid/nsGrid.cpp b/layout/xul/grid/nsGrid.cpp
new file mode 100644
index 0000000000..762bbfcd78
--- /dev/null
+++ b/layout/xul/grid/nsGrid.cpp
@@ -0,0 +1,1276 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsGrid.h"
+#include "nsGridRowGroupLayout.h"
+#include "nsBox.h"
+#include "nsIScrollableFrame.h"
+#include "nsSprocketLayout.h"
+#include "nsGridLayout2.h"
+#include "nsGridRow.h"
+#include "nsGridCell.h"
+#include "mozilla/ReflowInput.h"
+
+/*
+The grid control expands the idea of boxes from 1 dimension to 2 dimensions. 
+It works by allowing the XUL to define a collection of rows and columns and then 
+stacking them on top of each other. Here is and example.
+
+Example 1:
+
+<grid>
+   <columns>
+      <column/>
+      <column/>
+   </columns>
+
+   <rows>
+      <row/>
+      <row/>
+   </rows>
+</grid>
+
+example 2:
+
+<grid>
+   <columns>
+      <column flex="1"/>
+      <column flex="1"/>
+   </columns>
+
+   <rows>
+      <row>
+         <text value="hello"/>
+         <text value="there"/>
+      </row>
+   </rows>
+</grid>
+
+example 3:
+
+<grid>
+
+<rows>
+      <row>
+         <text value="hello"/>
+         <text value="there"/>
+      </row>
+   </rows>
+
+   <columns>
+      <column>
+         <text value="Hey I'm in the column and I'm on top!"/>
+      </column>
+      <column/>
+   </columns>
+
+</grid>
+
+Usually the columns are first and the rows are second, so the rows will be drawn on top of the columns. 
+You can reverse this by defining the rows first.
+Other tags are then placed in the <row> or <column> tags causing the grid to accommodate everyone.  
+It does this by creating 3 things: A cellmap, a row list, and a column list. The cellmap is a 2 
+dimensional array of nsGridCells. Each cell contains 2 boxes.  One cell from the column list 
+and one from the row list. When a cell is asked for its size it returns that smallest size it can 
+be to accommodate the 2 cells. Row lists and Column lists use the same data structure: nsGridRow. 
+Essentially a row and column are the same except a row goes alone the x axis and a column the y. 
+To make things easier and save code everything is written in terms of the x dimension. A flag is 
+passed in called "isHorizontal" that can flip the calculations to the y axis.
+
+Usually the number of cells in a row match the number of columns, but not always. 
+It is possible to define 5 columns for a grid but have 10 cells in one of the rows. 
+In this case 5 extra columns will be added to the column list to handle the situation. 
+These are called extraColumns/Rows.
+*/
+
+using namespace mozilla;
+
+nsGrid::nsGrid():mBox(nullptr),
+                 mRowsBox(nullptr),
+                 mColumnsBox(nullptr),
+                 mNeedsRebuild(true),
+                 mRowCount(0),
+                 mColumnCount(0),
+                 mExtraRowCount(0),
+                 mExtraColumnCount(0),
+                 mMarkingDirty(false)
+{
+    MOZ_COUNT_CTOR(nsGrid);
+}
+
+nsGrid::~nsGrid()
+{
+    FreeMap();
+    MOZ_COUNT_DTOR(nsGrid);
+}
+
+/*
+ * This is called whenever something major happens in the grid. And example 
+ * might be when many cells or row are added. It sets a flag signaling that 
+ * all the grids caches information should be recalculated.
+ */
+void
+nsGrid::NeedsRebuild(nsBoxLayoutState& aState)
+{
+  if (mNeedsRebuild)
+    return;
+
+  // iterate through columns and rows and dirty them
+  mNeedsRebuild = true;
+
+  // find the new row and column box. They could have 
+  // been changed.
+  mRowsBox = nullptr;
+  mColumnsBox = nullptr;
+  FindRowsAndColumns(&mRowsBox, &mColumnsBox);
+
+  // tell all the rows and columns they are dirty
+  DirtyRows(mRowsBox, aState);
+  DirtyRows(mColumnsBox, aState);
+}
+
+
+
+/**
+ * If we are marked for rebuild. Then build everything
+ */
+void
+nsGrid::RebuildIfNeeded()
+{
+  if (!mNeedsRebuild)
+    return;
+
+  mNeedsRebuild = false;
+
+  // find the row and columns frames
+  FindRowsAndColumns(&mRowsBox, &mColumnsBox);
+
+  // count the rows and columns
+  int32_t computedRowCount = 0;
+  int32_t computedColumnCount = 0;
+  int32_t rowCount = 0;
+  int32_t columnCount = 0;
+
+  CountRowsColumns(mRowsBox, rowCount, computedColumnCount);
+  CountRowsColumns(mColumnsBox, columnCount, computedRowCount);
+
+  // computedRowCount are the actual number of rows as determined by the 
+  // columns children.
+  // computedColumnCount are the number of columns as determined by the number
+  // of rows children.
+  // We can use this information to see how many extra columns or rows we need.
+  // This can happen if there are are more children in a row that number of columns
+  // defined. Example:
+  //
+  // <columns>
+  //   <column/>
+  // </columns>
+  //
+  // <rows>
+  //   <row>
+  //     <button/><button/>
+  //   </row>
+  // </rows>
+  //
+  // computedColumnCount = 2 // for the 2 buttons in the row tag
+  // computedRowCount = 0 // there is nothing in the  column tag
+  // mColumnCount = 1 // one column defined
+  // mRowCount = 1 // one row defined
+  // 
+  // So in this case we need to make 1 extra column.
+  //
+
+  // Make sure to update mExtraColumnCount no matter what, since it might
+  // happen that we now have as many columns as are defined, and we wouldn't
+  // want to have a positive mExtraColumnCount hanging about in that case!
+  mExtraColumnCount = computedColumnCount - columnCount;
+  if (computedColumnCount > columnCount) {
+     columnCount = computedColumnCount;
+  }
+
+  // Same for rows.
+  mExtraRowCount = computedRowCount - rowCount;
+  if (computedRowCount > rowCount) {
+     rowCount = computedRowCount;
+  }
+
+  // build and poplulate row and columns arrays
+  mRows = BuildRows(mRowsBox, rowCount, true);
+  mColumns = BuildRows(mColumnsBox, columnCount, false);
+
+  // build and populate the cell map
+  mCellMap = BuildCellMap(rowCount, columnCount);
+
+  mRowCount = rowCount;
+  mColumnCount = columnCount;
+
+  // populate the cell map from column and row children
+  PopulateCellMap(mRows.get(), mColumns.get(), mRowCount, mColumnCount, true);
+  PopulateCellMap(mColumns.get(), mRows.get(), mColumnCount, mRowCount, false);
+}
+
+void
+nsGrid::FreeMap()
+{
+  mRows = nullptr;
+  mColumns = nullptr;
+  mCellMap = nullptr;
+  mColumnCount = 0;
+  mRowCount = 0;
+  mExtraColumnCount = 0;
+  mExtraRowCount = 0;
+  mRowsBox = nullptr;
+  mColumnsBox = nullptr;
+}
+
+/**
+ * finds the first <rows> and <columns> tags in the <grid> tag
+ */
+void
+nsGrid::FindRowsAndColumns(nsIFrame** aRows, nsIFrame** aColumns)
+{
+  *aRows = nullptr;
+  *aColumns = nullptr;
+
+  // find the boxes that contain our rows and columns
+  nsIFrame* child = nullptr;
+  // if we have <grid></grid> then mBox will be null (bug 125689)
+  if (mBox)
+    child = nsBox::GetChildXULBox(mBox);
+
+  while(child)
+  {
+    nsIFrame* oldBox = child;
+    nsIScrollableFrame *scrollFrame = do_QueryFrame(child);
+    if (scrollFrame) {
+       nsIFrame* scrolledFrame = scrollFrame->GetScrolledFrame();
+       NS_ASSERTION(scrolledFrame,"Error no scroll frame!!");
+       child = do_QueryFrame(scrolledFrame);
+    }
+
+    nsCOMPtr<nsIGridPart> monument = GetPartFromBox(child);
+    if (monument)
+    {
+      nsGridRowGroupLayout* rowGroup = monument->CastToRowGroupLayout();
+      if (rowGroup) {
+         bool isHorizontal = !nsSprocketLayout::IsXULHorizontal(child);
+         if (isHorizontal)
+           *aRows = child;
+         else
+           *aColumns = child;
+
+         if (*aRows && *aColumns)
+           return;
+      }
+    }
+
+    if (scrollFrame) {
+      child = oldBox;
+    }
+
+    child = nsBox::GetNextXULBox(child);
+  }
+}
+
+/**
+ * Count the number of rows and columns in the given box. aRowCount well become the actual number
+ * rows defined in the xul. aComputedColumnCount will become the number of columns by counting the number
+ * of cells in each row.
+ */
+void
+nsGrid::CountRowsColumns(nsIFrame* aRowBox, int32_t& aRowCount, int32_t& aComputedColumnCount)
+{
+  aRowCount = 0;
+  aComputedColumnCount = 0;
+  // get the rowboxes layout manager. Then ask it to do the work for us
+  if (aRowBox) {
+    nsCOMPtr<nsIGridPart> monument = GetPartFromBox(aRowBox);
+    if (monument) 
+       monument->CountRowsColumns(aRowBox, aRowCount, aComputedColumnCount);
+  }
+}
+
+
+/**
+ * Given the number of rows create nsGridRow objects for them and full them out.
+ */
+UniquePtr<nsGridRow[]>
+nsGrid::BuildRows(nsIFrame* aBox, int32_t aRowCount, bool aIsHorizontal)
+{
+  // if no rows then return null
+  if (aRowCount == 0) {
+    return nullptr;
+  }
+
+  // create the array
+  UniquePtr<nsGridRow[]> row;
+  
+  // only create new rows if we have to. Reuse old rows.
+  if (aIsHorizontal)
+  { 
+    if (aRowCount > mRowCount) {
+       row = MakeUnique<nsGridRow[]>(aRowCount);
+    } else {
+      for (int32_t i=0; i < mRowCount; i++)
+        mRows[i].Init(nullptr, false);
+
+      row = Move(mRows);
+    }
+  } else {
+    if (aRowCount > mColumnCount) {
+       row = MakeUnique<nsGridRow[]>(aRowCount);
+    } else {
+       for (int32_t i=0; i < mColumnCount; i++)
+         mColumns[i].Init(nullptr, false);
+
+       row = Move(mColumns);
+    }
+  }
+
+  // populate it if we can. If not it will contain only dynamic columns
+  if (aBox)
+  {
+    nsCOMPtr<nsIGridPart> monument = GetPartFromBox(aBox);
+    if (monument) {
+       monument->BuildRows(aBox, row.get());
+    }
+  }
+
+  return row;
+}
+
+
+/**
+ * Given the number of rows and columns. Build a cellmap
+ */
+UniquePtr<nsGridCell[]>
+nsGrid::BuildCellMap(int32_t aRows, int32_t aColumns)
+{
+  int32_t size = aRows*aColumns;
+  int32_t oldsize = mRowCount*mColumnCount;
+  if (size == 0) {
+    return nullptr;
+  }
+
+  if (size > oldsize) {
+    return MakeUnique<nsGridCell[]>(size);
+  }
+
+  // clear out cellmap
+  for (int32_t i=0; i < oldsize; i++) {
+    mCellMap[i].SetBoxInRow(nullptr);
+    mCellMap[i].SetBoxInColumn(nullptr);
+  }
+  return Move(mCellMap);
+}
+
+/** 
+ * Run through all the cells in the rows and columns and populate then with 2 cells. One from the row and one
+ * from the column
+ */
+void
+nsGrid::PopulateCellMap(nsGridRow* aRows, nsGridRow* aColumns, int32_t aRowCount, int32_t aColumnCount, bool aIsHorizontal)
+{
+  if (!aRows)
+    return;
+
+   // look through the columns
+  int32_t j = 0;
+
+  for(int32_t i=0; i < aRowCount; i++) 
+  {
+     nsIFrame* child = nullptr;
+     nsGridRow* row = &aRows[i];
+
+     // skip bogus rows. They have no cells
+     if (row->mIsBogus) 
+       continue;
+
+     child = row->mBox;
+     if (child) {
+       child = nsBox::GetChildXULBox(child);
+
+       j = 0;
+
+       while(child && j < aColumnCount)
+       {
+         // skip bogus column. They have no cells
+         nsGridRow* column = &aColumns[j];
+         if (column->mIsBogus) 
+         {
+           j++;
+           continue;
+         }
+
+         if (aIsHorizontal)
+           GetCellAt(j,i)->SetBoxInRow(child);
+         else
+           GetCellAt(i,j)->SetBoxInColumn(child);
+
+         child = nsBox::GetNextXULBox(child);
+
+         j++;
+       }
+     }
+  }
+}
+
+/**
+ * Run through the rows in the given box and mark them dirty so they 
+ * will get recalculated and get a layout.
+ */
+void 
+nsGrid::DirtyRows(nsIFrame* aRowBox, nsBoxLayoutState& aState)
+{
+  // make sure we prevent others from dirtying things.
+  mMarkingDirty = true;
+
+  // if the box is a grid part have it recursively hand it.
+  if (aRowBox) {
+    nsCOMPtr<nsIGridPart> part = GetPartFromBox(aRowBox);
+    if (part) 
+       part->DirtyRows(aRowBox, aState);
+  }
+
+  mMarkingDirty = false;
+}
+
+nsGridRow*
+nsGrid::GetColumnAt(int32_t aIndex, bool aIsHorizontal)
+{
+  return GetRowAt(aIndex, !aIsHorizontal);
+}
+
+nsGridRow*
+nsGrid::GetRowAt(int32_t aIndex, bool aIsHorizontal)
+{
+  RebuildIfNeeded();
+
+  if (aIsHorizontal) {
+    NS_ASSERTION(aIndex < mRowCount && aIndex >= 0, "Index out of range");
+    return &mRows[aIndex];
+  } else {
+    NS_ASSERTION(aIndex < mColumnCount && aIndex >= 0, "Index out of range");
+    return &mColumns[aIndex];
+  }
+}
+
+nsGridCell*
+nsGrid::GetCellAt(int32_t aX, int32_t aY)
+{
+  RebuildIfNeeded();
+
+  NS_ASSERTION(aY < mRowCount && aY >= 0, "Index out of range");
+  NS_ASSERTION(aX < mColumnCount && aX >= 0, "Index out of range");
+  return &mCellMap[aY*mColumnCount+aX];
+}
+
+int32_t
+nsGrid::GetExtraColumnCount(bool aIsHorizontal)
+{
+  return GetExtraRowCount(!aIsHorizontal);
+}
+
+int32_t
+nsGrid::GetExtraRowCount(bool aIsHorizontal)
+{
+  RebuildIfNeeded();
+
+  if (aIsHorizontal)
+    return mExtraRowCount;
+  else
+    return mExtraColumnCount;
+}
+
+
+/**
+ * These methods return the preferred, min, max sizes for a given row index.
+ * aIsHorizontal if aIsHorizontal is true. If you pass false you will get the inverse.
+ * As if you called GetPrefColumnSize(aState, index, aPref)
+ */
+nsSize
+nsGrid::GetPrefRowSize(nsBoxLayoutState& aState, int32_t aRowIndex, bool aIsHorizontal)
+{ 
+  nsSize size(0,0);
+  if (!(aRowIndex >=0 && aRowIndex < GetRowCount(aIsHorizontal)))
+    return size;
+
+  nscoord height = GetPrefRowHeight(aState, aRowIndex, aIsHorizontal);
+  SetLargestSize(size, height, aIsHorizontal);
+
+  return size;
+}
+
+nsSize
+nsGrid::GetMinRowSize(nsBoxLayoutState& aState, int32_t aRowIndex, bool aIsHorizontal)
+{ 
+  nsSize size(0,0);
+  if (!(aRowIndex >=0 && aRowIndex < GetRowCount(aIsHorizontal)))
+    return size;
+
+  nscoord height = GetMinRowHeight(aState, aRowIndex, aIsHorizontal);
+  SetLargestSize(size, height, aIsHorizontal);
+
+  return size;
+}
+
+nsSize
+nsGrid::GetMaxRowSize(nsBoxLayoutState& aState, int32_t aRowIndex, bool aIsHorizontal)
+{ 
+  nsSize size(NS_INTRINSICSIZE,NS_INTRINSICSIZE);
+  if (!(aRowIndex >=0 && aRowIndex < GetRowCount(aIsHorizontal)))
+    return size;
+
+  nscoord height = GetMaxRowHeight(aState, aRowIndex, aIsHorizontal);
+  SetSmallestSize(size, height, aIsHorizontal);
+
+  return size;
+}
+
+// static
+nsIGridPart*
+nsGrid::GetPartFromBox(nsIFrame* aBox)
+{
+  if (!aBox)
+    return nullptr;
+
+  nsBoxLayout* layout = aBox->GetXULLayoutManager();
+  return layout ? layout->AsGridPart() : nullptr;
+}
+
+nsMargin
+nsGrid::GetBoxTotalMargin(nsIFrame* aBox, bool aIsHorizontal)
+{
+  nsMargin margin(0,0,0,0);
+  // walk the boxes parent chain getting the border/padding/margin of our parent rows
+  
+  // first get the layour manager
+  nsIGridPart* part = GetPartFromBox(aBox);
+  if (part)
+    margin = part->GetTotalMargin(aBox, aIsHorizontal);
+
+  return margin;
+}
+
+/**
+ * The first and last rows can be affected by <rows> tags with borders or margin
+ * gets first and last rows and their indexes.
+ * If it fails because there are no rows then:
+ * FirstRow is nullptr
+ * LastRow is nullptr
+ * aFirstIndex = -1
+ * aLastIndex = -1
+ */
+void
+nsGrid::GetFirstAndLastRow(int32_t& aFirstIndex,
+                           int32_t& aLastIndex,
+                           nsGridRow*& aFirstRow,
+                           nsGridRow*& aLastRow,
+                           bool aIsHorizontal)
+{
+  aFirstRow = nullptr;
+  aLastRow = nullptr;
+  aFirstIndex = -1;
+  aLastIndex = -1;
+
+  int32_t count = GetRowCount(aIsHorizontal);
+
+  if (count == 0)
+    return;
+
+
+  // We could have collapsed columns either before or after our index.
+  // they should not count. So if we are the 5th row and the first 4 are
+  // collaped we become the first row. Or if we are the 9th row and
+  // 10 up to the last row are collapsed we then become the last.
+
+  // see if we are first
+  int32_t i;
+  for (i=0; i < count; i++)
+  {
+     nsGridRow* row = GetRowAt(i,aIsHorizontal);
+     if (!row->IsXULCollapsed()) {
+       aFirstIndex = i;
+       aFirstRow = row;
+       break;
+     }
+  }
+
+  // see if we are last
+  for (i=count-1; i >= 0; i--)
+  {
+     nsGridRow* row = GetRowAt(i,aIsHorizontal);
+     if (!row->IsXULCollapsed()) {
+       aLastIndex = i;
+       aLastRow = row;
+       break;
+     }
+
+  }
+}
+
+/**
+ * A row can have a top and bottom offset. Usually this is just the top and bottom border/padding.
+ * However if the row is the first or last it could be affected by the fact a column or columns could
+ * have a top or bottom margin. 
+ */
+void
+nsGrid::GetRowOffsets(int32_t aIndex, nscoord& aTop, nscoord& aBottom, bool aIsHorizontal)
+{
+
+  RebuildIfNeeded();
+
+  nsGridRow* row = GetRowAt(aIndex, aIsHorizontal);
+
+  if (row->IsOffsetSet()) 
+  {
+    aTop    = row->mTop;
+    aBottom = row->mBottom;
+    return;
+  }
+
+  // first get the rows top and bottom border and padding
+  nsIFrame* box = row->GetBox();
+
+  // add up all the padding
+  nsMargin margin(0,0,0,0);
+  nsMargin border(0,0,0,0);
+  nsMargin padding(0,0,0,0);
+  nsMargin totalBorderPadding(0,0,0,0);
+  nsMargin totalMargin(0,0,0,0);
+
+  // if there is a box and it's not bogus take its
+  // borders padding into account
+  if (box && !row->mIsBogus)
+  {
+    if (!box->IsXULCollapsed())
+    {
+       // get real border and padding. GetXULBorderAndPadding
+       // is redefined on nsGridRowLeafFrame. If we called it here
+       // we would be in finite recurson.
+       box->GetXULBorder(border);
+       box->GetXULPadding(padding);
+
+       totalBorderPadding += border;
+       totalBorderPadding += padding;
+     }
+
+     // if we are the first or last row
+     // take into account <rows> tags around us
+     // that could have borders or margins.
+     // fortunately they only affect the first
+     // and last row inside the <rows> tag
+
+     totalMargin = GetBoxTotalMargin(box, aIsHorizontal);
+  }
+
+  if (aIsHorizontal) {
+    row->mTop = totalBorderPadding.top;
+    row->mBottom = totalBorderPadding.bottom;
+    row->mTopMargin = totalMargin.top;
+    row->mBottomMargin = totalMargin.bottom;
+  } else {
+    row->mTop = totalBorderPadding.left;
+    row->mBottom = totalBorderPadding.right;
+    row->mTopMargin = totalMargin.left;
+    row->mBottomMargin = totalMargin.right;
+  }
+
+  // if we are the first or last row take into account the top and bottom borders
+  // of each columns. 
+
+  // If we are the first row then get the largest top border/padding in 
+  // our columns. If that's larger than the rows top border/padding use it.
+
+  // If we are the last row then get the largest bottom border/padding in 
+  // our columns. If that's larger than the rows bottom border/padding use it.
+  int32_t firstIndex = 0;
+  int32_t lastIndex = 0;
+  nsGridRow* firstRow = nullptr;
+  nsGridRow* lastRow = nullptr;
+  GetFirstAndLastRow(firstIndex, lastIndex, firstRow, lastRow, aIsHorizontal);
+
+  if (aIndex == firstIndex || aIndex == lastIndex) {
+    nscoord maxTop = 0;
+    nscoord maxBottom = 0;
+
+    // run through the columns. Look at each column
+    // pick the largest top border or bottom border
+    int32_t count = GetColumnCount(aIsHorizontal); 
+
+    for (int32_t i=0; i < count; i++)
+    {  
+      nsMargin totalChildBorderPadding(0,0,0,0);
+
+      nsGridRow* column = GetColumnAt(i,aIsHorizontal);
+      nsIFrame* box = column->GetBox();
+
+      if (box) 
+      {
+        // ignore collapsed children
+        if (!box->IsXULCollapsed())
+        {
+           // include the margin of the columns. To the row
+           // at this point border/padding and margins all added
+           // up to more needed space.
+           margin = GetBoxTotalMargin(box, !aIsHorizontal);
+           // get real border and padding. GetXULBorderAndPadding
+           // is redefined on nsGridRowLeafFrame. If we called it here
+           // we would be in finite recurson.
+           box->GetXULBorder(border);
+           box->GetXULPadding(padding);
+           totalChildBorderPadding += border;
+           totalChildBorderPadding += padding;
+           totalChildBorderPadding += margin;
+        }
+
+        nscoord top;
+        nscoord bottom;
+
+        // pick the largest top margin
+        if (aIndex == firstIndex) {
+          if (aIsHorizontal) {
+            top = totalChildBorderPadding.top;
+          } else {
+            top = totalChildBorderPadding.left;
+          }
+          if (top > maxTop)
+            maxTop = top;
+        } 
+
+        // pick the largest bottom margin
+        if (aIndex == lastIndex) {
+          if (aIsHorizontal) {
+            bottom = totalChildBorderPadding.bottom;
+          } else {
+            bottom = totalChildBorderPadding.right;
+          }
+          if (bottom > maxBottom)
+             maxBottom = bottom;
+        }
+
+      }
+    
+      // If the biggest top border/padding the columns is larger than this rows top border/padding
+      // the use it.
+      if (aIndex == firstIndex) {
+        if (maxTop > (row->mTop + row->mTopMargin))
+          row->mTop = maxTop - row->mTopMargin;
+      }
+
+      // If the biggest bottom border/padding the columns is larger than this rows bottom border/padding
+      // the use it.
+      if (aIndex == lastIndex) {
+        if (maxBottom > (row->mBottom + row->mBottomMargin))
+          row->mBottom = maxBottom - row->mBottomMargin;
+      }
+    }
+  }
+  
+  aTop    = row->mTop;
+  aBottom = row->mBottom;
+}
+
+/**
+ * These methods return the preferred, min, max coord for a given row index if
+ * aIsHorizontal is true. If you pass false you will get the inverse.
+ * As if you called GetPrefColumnHeight(aState, index, aPref).
+ */
+nscoord
+nsGrid::GetPrefRowHeight(nsBoxLayoutState& aState, int32_t aIndex, bool aIsHorizontal)
+{
+  RebuildIfNeeded();
+
+  nsGridRow* row = GetRowAt(aIndex, aIsHorizontal);
+
+  if (row->IsXULCollapsed())
+    return 0;
+
+  if (row->IsPrefSet()) 
+    return row->mPref;
+
+  nsIFrame* box = row->mBox;
+
+  // set in CSS?
+  if (box) 
+  {
+    bool widthSet, heightSet;
+    nsSize cssSize(-1, -1);
+    nsIFrame::AddXULPrefSize(box, cssSize, widthSet, heightSet);
+
+    row->mPref = GET_HEIGHT(cssSize, aIsHorizontal);
+
+    // yep do nothing.
+    if (row->mPref != -1)
+      return row->mPref;
+  }
+
+  // get the offsets so they are cached.
+  nscoord top;
+  nscoord bottom;
+  GetRowOffsets(aIndex, top, bottom, aIsHorizontal);
+
+  // is the row bogus? If so then just ask it for its size
+  // it should not be affected by cells in the grid. 
+  if (row->mIsBogus)
+  {
+     nsSize size(0,0);
+     if (box) 
+     {
+       size = box->GetXULPrefSize(aState);
+       nsBox::AddMargin(box, size);
+       nsGridLayout2::AddOffset(box, size);
+     }
+
+     row->mPref = GET_HEIGHT(size, aIsHorizontal);
+     return row->mPref;
+  }
+
+  nsSize size(0,0);
+
+  nsGridCell* child;
+
+  int32_t count = GetColumnCount(aIsHorizontal); 
+
+  for (int32_t i=0; i < count; i++)
+  {  
+    if (aIsHorizontal)
+     child = GetCellAt(i,aIndex);
+    else
+     child = GetCellAt(aIndex,i);
+
+    // ignore collapsed children
+    if (!child->IsXULCollapsed())
+    {
+      nsSize childSize = child->GetXULPrefSize(aState);
+
+      nsSprocketLayout::AddLargestSize(size, childSize, aIsHorizontal);
+    }
+  }
+
+  row->mPref = GET_HEIGHT(size, aIsHorizontal) + top + bottom;
+
+  return row->mPref;
+}
+
+nscoord
+nsGrid::GetMinRowHeight(nsBoxLayoutState& aState, int32_t aIndex, bool aIsHorizontal)
+{
+  RebuildIfNeeded();
+
+  nsGridRow* row = GetRowAt(aIndex, aIsHorizontal);
+
+  if (row->IsXULCollapsed())
+    return 0;
+
+  if (row->IsMinSet()) 
+    return row->mMin;
+
+  nsIFrame* box = row->mBox;
+
+  // set in CSS?
+  if (box) {
+    bool widthSet, heightSet;
+    nsSize cssSize(-1, -1);
+    nsIFrame::AddXULMinSize(aState, box, cssSize, widthSet, heightSet);
+
+    row->mMin = GET_HEIGHT(cssSize, aIsHorizontal);
+
+    // yep do nothing.
+    if (row->mMin != -1)
+      return row->mMin;
+  }
+
+  // get the offsets so they are cached.
+  nscoord top;
+  nscoord bottom;
+  GetRowOffsets(aIndex, top, bottom, aIsHorizontal);
+
+  // is the row bogus? If so then just ask it for its size
+  // it should not be affected by cells in the grid. 
+  if (row->mIsBogus)
+  {
+     nsSize size(0,0);
+     if (box) {
+       size = box->GetXULPrefSize(aState);
+       nsBox::AddMargin(box, size);
+       nsGridLayout2::AddOffset(box, size);
+     }
+
+     row->mMin = GET_HEIGHT(size, aIsHorizontal) + top + bottom;
+     return row->mMin;
+  }
+
+  nsSize size(0,0);
+
+  nsGridCell* child;
+
+  int32_t count = GetColumnCount(aIsHorizontal); 
+
+  for (int32_t i=0; i < count; i++)
+  {  
+    if (aIsHorizontal)
+     child = GetCellAt(i,aIndex);
+    else
+     child = GetCellAt(aIndex,i);
+
+    // ignore collapsed children
+    if (!child->IsXULCollapsed())
+    {
+      nsSize childSize = child->GetXULMinSize(aState);
+
+      nsSprocketLayout::AddLargestSize(size, childSize, aIsHorizontal);
+    }
+  }
+
+  row->mMin = GET_HEIGHT(size, aIsHorizontal);
+
+  return row->mMin;
+}
+
+nscoord
+nsGrid::GetMaxRowHeight(nsBoxLayoutState& aState, int32_t aIndex, bool aIsHorizontal)
+{
+  RebuildIfNeeded();
+
+  nsGridRow* row = GetRowAt(aIndex, aIsHorizontal);
+
+  if (row->IsXULCollapsed())
+    return 0;
+
+  if (row->IsMaxSet()) 
+    return row->mMax;
+
+  nsIFrame* box = row->mBox;
+
+  // set in CSS?
+  if (box) {
+    bool widthSet, heightSet;
+    nsSize cssSize(-1, -1);
+    nsIFrame::AddXULMaxSize(box, cssSize, widthSet, heightSet);
+
+    row->mMax = GET_HEIGHT(cssSize, aIsHorizontal);
+
+    // yep do nothing.
+    if (row->mMax != -1)
+      return row->mMax;
+  }
+
+  // get the offsets so they are cached.
+  nscoord top;
+  nscoord bottom;
+  GetRowOffsets(aIndex, top, bottom, aIsHorizontal);
+
+  // is the row bogus? If so then just ask it for its size
+  // it should not be affected by cells in the grid. 
+  if (row->mIsBogus)
+  {
+     nsSize size(NS_INTRINSICSIZE,NS_INTRINSICSIZE);
+     if (box) {
+       size = box->GetXULPrefSize(aState);
+       nsBox::AddMargin(box, size);
+       nsGridLayout2::AddOffset(box, size);
+     }
+
+     row->mMax = GET_HEIGHT(size, aIsHorizontal);
+     return row->mMax;
+  }
+
+  nsSize size(NS_INTRINSICSIZE,NS_INTRINSICSIZE);
+
+  nsGridCell* child;
+
+  int32_t count = GetColumnCount(aIsHorizontal); 
+
+  for (int32_t i=0; i < count; i++)
+  {  
+    if (aIsHorizontal)
+     child = GetCellAt(i,aIndex);
+    else
+     child = GetCellAt(aIndex,i);
+
+    // ignore collapsed children
+    if (!child->IsXULCollapsed())
+    {
+      nsSize min = child->GetXULMinSize(aState);
+      nsSize childSize = nsBox::BoundsCheckMinMax(min, child->GetXULMaxSize(aState));
+      nsSprocketLayout::AddLargestSize(size, childSize, aIsHorizontal);
+    }
+  }
+
+  row->mMax = GET_HEIGHT(size, aIsHorizontal) + top + bottom;
+
+  return row->mMax;
+}
+
+bool
+nsGrid::IsGrid(nsIFrame* aBox)
+{
+  nsIGridPart* part = GetPartFromBox(aBox);
+  if (!part)
+    return false;
+
+  nsGridLayout2* grid = part->CastToGridLayout();
+
+  if (grid)
+    return true;
+
+  return false;
+}
+
+/**
+ * This get the flexibilty of the row at aIndex. It's not trivial. There are a few
+ * things we need to look at. Specifically we need to see if any <rows> or <columns>
+ * tags are around us. Their flexibilty will affect ours.
+ */
+nscoord
+nsGrid::GetRowFlex(int32_t aIndex, bool aIsHorizontal)
+{
+  RebuildIfNeeded();
+
+  nsGridRow* row = GetRowAt(aIndex, aIsHorizontal);
+
+  if (row->IsFlexSet()) 
+    return row->mFlex;
+
+  nsIFrame* box = row->mBox;
+  row->mFlex = 0;
+
+  if (box) {
+
+    // We need our flex but a inflexible row could be around us. If so
+    // neither are we. However if its the row tag just inside the grid it won't 
+    // affect us. We need to do this for this case:
+    // <grid> 
+    //   <rows> 
+    //     <rows> // this is not flexible. So our children should not be flexible
+    //        <row flex="1"/>
+    //        <row flex="1"/>
+    //     </rows>
+    //        <row/>
+    //   </rows>
+    // </grid>
+    //
+    // or..
+    //
+    // <grid> 
+    //  <rows>
+    //   <rows> // this is not flexible. So our children should not be flexible
+    //     <rows flex="1"> 
+    //        <row flex="1"/>
+    //        <row flex="1"/>
+    //     </rows>
+    //        <row/>
+    //   </rows>
+    //  </row>
+    // </grid>
+
+
+    // So here is how it looks
+    //
+    // <grid>     
+    //   <rows>   // parentsParent
+    //     <rows> // parent
+    //        <row flex="1"/> 
+    //        <row flex="1"/>
+    //     </rows>
+    //        <row/>
+    //   </rows>
+    // </grid>
+
+    // so the answer is simple: 1) Walk our parent chain. 2) If we find
+    // someone who is not flexible and they aren't the rows immediately in
+    // the grid. 3) Then we are not flexible
+
+    box = GetScrollBox(box);
+    nsIFrame* parent = nsBox::GetParentXULBox(box);
+    nsIFrame* parentsParent=nullptr;
+
+    while(parent)
+    {
+      parent = GetScrollBox(parent);
+      parentsParent = nsBox::GetParentXULBox(parent);
+
+      // if our parents parent is not a grid
+      // the get its flex. If its 0 then we are
+      // not flexible.
+      if (parentsParent) {
+        if (!IsGrid(parentsParent)) {
+          nscoord flex = parent->GetXULFlex();
+          nsIFrame::AddXULFlex(parent, flex);
+          if (flex == 0) {
+            row->mFlex = 0;
+            return row->mFlex;
+          }
+        } else 
+          break;
+      }
+
+      parent = parentsParent;
+    }
+    
+    // get the row flex.
+    row->mFlex = box->GetXULFlex();
+    nsIFrame::AddXULFlex(box, row->mFlex);
+  }
+
+  return row->mFlex;
+}
+
+void
+nsGrid::SetLargestSize(nsSize& aSize, nscoord aHeight, bool aIsHorizontal)
+{
+  if (aIsHorizontal) {
+    if (aSize.height < aHeight)
+      aSize.height = aHeight;
+  } else {
+    if (aSize.width < aHeight)
+      aSize.width = aHeight;
+  }
+}
+
+void
+nsGrid::SetSmallestSize(nsSize& aSize, nscoord aHeight, bool aIsHorizontal)
+{
+  if (aIsHorizontal) {
+    if (aSize.height > aHeight)
+      aSize.height = aHeight;
+  } else {
+    if (aSize.width < aHeight)
+      aSize.width = aHeight;
+  }
+}
+
+int32_t 
+nsGrid::GetRowCount(int32_t aIsHorizontal)
+{
+  RebuildIfNeeded();
+
+  if (aIsHorizontal)
+    return mRowCount;
+  else
+    return mColumnCount;
+}
+
+int32_t 
+nsGrid::GetColumnCount(int32_t aIsHorizontal)
+{
+  return GetRowCount(!aIsHorizontal);
+}
+
+/*
+ * A cell in the given row or columns at the given index has had a child added or removed
+ */
+void 
+nsGrid::CellAddedOrRemoved(nsBoxLayoutState& aState, int32_t aIndex, bool aIsHorizontal)
+{
+  // TBD see if the cell will fit in our current row. If it will
+  // just add it in. 
+  // but for now rebuild everything.
+  if (mMarkingDirty)
+    return;
+
+  NeedsRebuild(aState);
+}
+
+/**
+ * A row or columns at the given index had been added or removed
+ */
+void 
+nsGrid::RowAddedOrRemoved(nsBoxLayoutState& aState, int32_t aIndex, bool aIsHorizontal)
+{
+  // TBD see if we have extra room in the table and just add the new row in
+  // for now rebuild the world
+  if (mMarkingDirty)
+    return;
+
+  NeedsRebuild(aState);
+}
+
+/*
+ * Scrollframes are tranparent. If this is given a scrollframe is will return the
+ * frame inside. If there is no scrollframe it does nothing.
+ */
+nsIFrame*
+nsGrid::GetScrolledBox(nsIFrame* aChild)
+{
+  // first see if it is a scrollframe. If so walk down into it and get the scrolled child
+      nsIScrollableFrame *scrollFrame = do_QueryFrame(aChild);
+      if (scrollFrame) {
+         nsIFrame* scrolledFrame = scrollFrame->GetScrolledFrame();
+         NS_ASSERTION(scrolledFrame,"Error no scroll frame!!");
+         return scrolledFrame;
+      }
+
+      return aChild;
+}
+
+/*
+ * Scrollframes are tranparent. If this is given a child in a scrollframe is will return the
+ * scrollframe ourside it. If there is no scrollframe it does nothing.
+ */
+nsIFrame*
+nsGrid::GetScrollBox(nsIFrame* aChild)
+{
+  if (!aChild)
+    return nullptr;
+
+  // get parent
+  nsIFrame* parent = nsBox::GetParentXULBox(aChild);
+
+  // walk up until we find a scrollframe or a part
+  // if it's a scrollframe return it.
+  // if it's a parent then the child passed does not
+  // have a scroll frame immediately wrapped around it.
+  while (parent) {
+    nsIScrollableFrame *scrollFrame = do_QueryFrame(parent);
+    // scrollframe? Yep return it.
+    if (scrollFrame)
+      return parent;
+
+    nsCOMPtr<nsIGridPart> parentGridRow = GetPartFromBox(parent);
+    // if a part then just return the child
+    if (parentGridRow) 
+      break;
+
+    parent = nsBox::GetParentXULBox(parent);
+  }
+
+  return aChild;
+}
+
+
+
+#ifdef DEBUG_grid
+void
+nsGrid::PrintCellMap()
+{
+  
+  printf("-----Columns------\n");
+  for (int x=0; x < mColumnCount; x++) 
+  {
+   
+    nsGridRow* column = GetColumnAt(x);
+    printf("%d(pf=%d, mn=%d, mx=%d) ", x, column->mPref, column->mMin, column->mMax);
+  }
+
+  printf("\n-----Rows------\n");
+  for (x=0; x < mRowCount; x++) 
+  {
+    nsGridRow* column = GetRowAt(x);
+    printf("%d(pf=%d, mn=%d, mx=%d) ", x, column->mPref, column->mMin, column->mMax);
+  }
+
+  printf("\n");
+  
+}
+#endif
diff --git a/layout/xul/grid/nsGrid.h b/layout/xul/grid/nsGrid.h
new file mode 100644
index 0000000000..d8726a9460
--- /dev/null
+++ b/layout/xul/grid/nsGrid.h
@@ -0,0 +1,132 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsGrid_h___
+#define nsGrid_h___
+
+#include "nsStackLayout.h"
+#include "nsIGridPart.h"
+#include "nsCOMPtr.h"
+#include "mozilla/UniquePtr.h"
+
+class nsBoxLayoutState;
+class nsGridCell;
+
+//#define DEBUG_grid 1
+
+/**
+ * The grid data structure, i.e., the grid cellmap.
+ */
+class nsGrid
+{
+public:
+  nsGrid();
+  ~nsGrid();
+
+  nsGridRow* GetColumnAt(int32_t aIndex, bool aIsHorizontal = true);
+  nsGridRow* GetRowAt(int32_t aIndex, bool aIsHorizontal = true);
+  nsGridCell* GetCellAt(int32_t aX, int32_t aY);
+
+  void NeedsRebuild(nsBoxLayoutState& aBoxLayoutState);
+  void RebuildIfNeeded();
+
+  // For all the methods taking an aIsHorizontal parameter:
+  // * When aIsHorizontal is true, the words "rows" and (for
+  //   GetColumnCount) "columns" refer to their normal meanings.
+  // * When aIsHorizontal is false, the meanings are flipped.
+  // FIXME:  Maybe eliminate GetColumnCount and change aIsHorizontal to
+  // aIsRows?  (Calling it horizontal doesn't really make sense because
+  // row groups and columns have vertical orientation, whereas column
+  // groups and rows are horizontal.)
+
+  nsSize GetPrefRowSize(nsBoxLayoutState& aBoxLayoutState, int32_t aRowIndex, bool aIsHorizontal = true);
+  nsSize GetMinRowSize(nsBoxLayoutState& aBoxLayoutState, int32_t aRowIndex, bool aIsHorizontal = true);
+  nsSize GetMaxRowSize(nsBoxLayoutState& aBoxLayoutState, int32_t aRowIndex, bool aIsHorizontal = true);
+  nscoord GetRowFlex(int32_t aRowIndex, bool aIsHorizontal = true);
+
+  nscoord GetPrefRowHeight(nsBoxLayoutState& aBoxLayoutState, int32_t aRowIndex, bool aIsHorizontal = true);
+  nscoord GetMinRowHeight(nsBoxLayoutState& aBoxLayoutState, int32_t aRowIndex, bool aIsHorizontal = true);
+  nscoord GetMaxRowHeight(nsBoxLayoutState& aBoxLayoutState, int32_t aRowIndex, bool aIsHorizontal = true);
+  void GetRowOffsets(int32_t aIndex, nscoord& aTop, nscoord& aBottom, bool aIsHorizontal = true);
+
+  void RowAddedOrRemoved(nsBoxLayoutState& aBoxLayoutState, int32_t aIndex, bool aIsHorizontal = true);
+  void CellAddedOrRemoved(nsBoxLayoutState& aBoxLayoutState, int32_t aIndex, bool aIsHorizontal = true);
+  void DirtyRows(nsIFrame* aRowBox, nsBoxLayoutState& aState);
+#ifdef DEBUG_grid
+  void PrintCellMap();
+#endif
+  int32_t GetExtraColumnCount(bool aIsHorizontal = true);
+  int32_t GetExtraRowCount(bool aIsHorizontal = true);
+
+// accessors
+  void SetBox(nsIFrame* aBox) { mBox = aBox; }
+  nsIFrame* GetBox() { return mBox; }
+  nsIFrame* GetRowsBox() { return mRowsBox; }
+  nsIFrame* GetColumnsBox() { return mColumnsBox; }
+  int32_t GetRowCount(int32_t aIsHorizontal = true);
+  int32_t GetColumnCount(int32_t aIsHorizontal = true);
+
+  static nsIFrame* GetScrolledBox(nsIFrame* aChild);
+  static nsIFrame* GetScrollBox(nsIFrame* aChild);
+  static nsIGridPart* GetPartFromBox(nsIFrame* aBox);
+  void GetFirstAndLastRow(int32_t& aFirstIndex,
+                          int32_t& aLastIndex,
+                          nsGridRow*& aFirstRow,
+                          nsGridRow*& aLastRow,
+                          bool aIsHorizontal);
+
+private:
+
+  nsMargin GetBoxTotalMargin(nsIFrame* aBox, bool aIsHorizontal = true);
+
+  void FreeMap();
+  void FindRowsAndColumns(nsIFrame** aRows, nsIFrame** aColumns);
+  mozilla::UniquePtr<nsGridRow[]> BuildRows(nsIFrame* aBox, int32_t aSize,
+                                            bool aIsHorizontal = true);
+  mozilla::UniquePtr<nsGridCell[]> BuildCellMap(int32_t aRows, int32_t aColumns);
+  void PopulateCellMap(nsGridRow* aRows, nsGridRow* aColumns, int32_t aRowCount, int32_t aColumnCount, bool aIsHorizontal = true);
+  void CountRowsColumns(nsIFrame* aBox, int32_t& aRowCount, int32_t& aComputedColumnCount);
+  void SetLargestSize(nsSize& aSize, nscoord aHeight, bool aIsHorizontal = true);
+  void SetSmallestSize(nsSize& aSize, nscoord aHeight, bool aIsHorizontal = true);
+  bool IsGrid(nsIFrame* aBox);
+
+  // the box that implement the <grid> tag
+  nsIFrame* mBox;
+
+  // an array of row object
+  mozilla::UniquePtr<nsGridRow[]> mRows;
+
+  // an array of columns objects.
+  mozilla::UniquePtr<nsGridRow[]> mColumns;
+
+  // the first in the <grid> that implements the <rows> tag.
+  nsIFrame* mRowsBox;
+
+  // the first in the <grid> that implements the <columns> tag.
+  nsIFrame* mColumnsBox;
+
+  // a flag that is false tells us to rebuild the who grid
+  bool mNeedsRebuild;
+
+  // number of rows and columns as defined by the XUL
+  int32_t mRowCount;
+  int32_t mColumnCount;
+
+  // number of rows and columns that are implied but not 
+  // explicitly defined int he XUL
+  int32_t mExtraRowCount;
+  int32_t mExtraColumnCount;
+
+  // x,y array of cells in the rows and columns
+  mozilla::UniquePtr<nsGridCell[]> mCellMap;
+
+  // a flag that when true suppresses all other MarkDirties. This
+  // prevents lots of extra work being done.
+  bool mMarkingDirty;
+};
+
+#endif
+
diff --git a/layout/xul/grid/nsGridCell.cpp b/layout/xul/grid/nsGridCell.cpp
new file mode 100644
index 0000000000..c54256297d
--- /dev/null
+++ b/layout/xul/grid/nsGridCell.cpp
@@ -0,0 +1,127 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsGridCell.h"
+#include "nsFrame.h"
+#include "nsBox.h"
+#include "nsGridLayout2.h"
+
+
+nsGridCell::nsGridCell():mBoxInColumn(nullptr),mBoxInRow(nullptr)
+{
+    MOZ_COUNT_CTOR(nsGridCell);
+}                                               
+        
+nsGridCell::~nsGridCell()
+{
+    MOZ_COUNT_DTOR(nsGridCell);
+}
+
+nsSize
+nsGridCell::GetXULPrefSize(nsBoxLayoutState& aState)
+{
+  nsSize sum(0,0);
+
+  // take our 2 children and add them up.
+  // we are as wide as the widest child plus its left offset
+  // we are tall as the tallest child plus its top offset
+
+  if (mBoxInColumn) {
+    nsSize pref = mBoxInColumn->GetXULPrefSize(aState);
+
+    nsBox::AddMargin(mBoxInColumn, pref);
+    nsGridLayout2::AddOffset(mBoxInColumn, pref);
+
+    nsBoxLayout::AddLargestSize(sum, pref);
+  }
+
+  if (mBoxInRow) {
+    nsSize pref = mBoxInRow->GetXULPrefSize(aState);
+
+    nsBox::AddMargin(mBoxInRow, pref);
+    nsGridLayout2::AddOffset(mBoxInRow, pref);
+
+    nsBoxLayout::AddLargestSize(sum, pref);
+  }
+
+  return sum;
+}
+
+nsSize
+nsGridCell::GetXULMinSize(nsBoxLayoutState& aState)
+{
+  nsSize sum(0, 0);
+
+  // take our 2 children and add them up.
+  // we are as wide as the widest child plus its left offset
+  // we are tall as the tallest child plus its top offset
+
+  if (mBoxInColumn) {
+    nsSize min = mBoxInColumn->GetXULMinSize(aState);
+
+    nsBox::AddMargin(mBoxInColumn, min);
+    nsGridLayout2::AddOffset(mBoxInColumn, min);
+
+    nsBoxLayout::AddLargestSize(sum, min);
+  }
+
+  if (mBoxInRow) {
+    nsSize min = mBoxInRow->GetXULMinSize(aState);
+
+    nsBox::AddMargin(mBoxInRow, min);
+    nsGridLayout2::AddOffset(mBoxInRow, min);
+
+    nsBoxLayout::AddLargestSize(sum, min);
+  }
+
+  return sum;
+}
+
+nsSize
+nsGridCell::GetXULMaxSize(nsBoxLayoutState& aState)
+{
+  nsSize sum(NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+
+  // take our 2 children and add them up.
+  // we are as wide as the smallest child plus its left offset
+  // we are tall as the shortest child plus its top offset
+
+  if (mBoxInColumn) {
+    nsSize max = mBoxInColumn->GetXULMaxSize(aState);
+ 
+    nsBox::AddMargin(mBoxInColumn, max);
+    nsGridLayout2::AddOffset(mBoxInColumn, max);
+
+    nsBoxLayout::AddSmallestSize(sum, max);
+  }
+
+  if (mBoxInRow) {
+    nsSize max = mBoxInRow->GetXULMaxSize(aState);
+
+    nsBox::AddMargin(mBoxInRow, max);
+    nsGridLayout2::AddOffset(mBoxInRow, max);
+
+    nsBoxLayout::AddSmallestSize(sum, max);
+  }
+
+  return sum;
+}
+
+
+bool
+nsGridCell::IsXULCollapsed()
+{
+  return ((mBoxInColumn && mBoxInColumn->IsXULCollapsed()) ||
+          (mBoxInRow && mBoxInRow->IsXULCollapsed()));
+}
+
+
diff --git a/layout/xul/grid/nsGridCell.h b/layout/xul/grid/nsGridCell.h
new file mode 100644
index 0000000000..eca652776f
--- /dev/null
+++ b/layout/xul/grid/nsGridCell.h
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ 
+  Author:
+  Eric D Vaughan
+
+**/
+
+#ifndef nsGridCell_h___
+#define nsGridCell_h___
+
+#include "mozilla/Attributes.h"
+
+class nsBoxLayoutState;
+struct nsSize;
+class nsIFrame;
+
+/*
+ * Grid cell is what makes up the cellmap in the grid. Each GridCell contains
+ * 2 pointers. One to the matching box in the columns and one to the matching box
+ * in the rows. Remember that you can put content in both rows and columns.
+ * When asked for preferred/min/max sizes it works like a stack and takes the 
+ * biggest sizes.
+ */
+
+class nsGridCell final
+{
+public:
+    nsGridCell();
+    ~nsGridCell();
+
+    nsSize      GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState);
+    nsSize      GetXULMinSize(nsBoxLayoutState& aBoxLayoutState);
+    nsSize      GetXULMaxSize(nsBoxLayoutState& aBoxLayoutState);
+    bool        IsXULCollapsed();
+
+// accessors
+    nsIFrame*   GetBoxInColumn()               { return mBoxInColumn; }
+    nsIFrame*   GetBoxInRow()                  { return mBoxInRow; }
+    void        SetBoxInRow(nsIFrame* aBox)    { mBoxInRow = aBox; }
+    void        SetBoxInColumn(nsIFrame* aBox) { mBoxInColumn = aBox; }
+
+private:
+    nsIFrame* mBoxInColumn;
+    nsIFrame* mBoxInRow;
+};
+
+#endif
+
diff --git a/layout/xul/grid/nsGridLayout2.cpp b/layout/xul/grid/nsGridLayout2.cpp
new file mode 100644
index 0000000000..75408dce38
--- /dev/null
+++ b/layout/xul/grid/nsGridLayout2.cpp
@@ -0,0 +1,266 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsGridLayout2.h"
+#include "nsGridRowGroupLayout.h"
+#include "nsGridRow.h"
+#include "nsBox.h"
+#include "nsIScrollableFrame.h"
+#include "nsSprocketLayout.h"
+#include "mozilla/ReflowInput.h"
+
+nsresult
+NS_NewGridLayout2( nsIPresShell* aPresShell, nsBoxLayout** aNewLayout)
+{
+  *aNewLayout = new nsGridLayout2(aPresShell);
+  NS_IF_ADDREF(*aNewLayout);
+
+  return NS_OK;
+  
+} 
+
+nsGridLayout2::nsGridLayout2(nsIPresShell* aPresShell):nsStackLayout()
+{
+}
+
+nsGridLayout2::~nsGridLayout2()
+{
+}
+
+// static
+void
+nsGridLayout2::AddOffset(nsIFrame* aChild, nsSize& aSize)
+{
+  nsMargin offset;
+  GetOffset(aChild, offset);
+  aSize.width += offset.left;
+  aSize.height += offset.top;
+}
+
+NS_IMETHODIMP
+nsGridLayout2::XULLayout(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  // XXX This should be set a better way!
+  mGrid.SetBox(aBox);
+  NS_ASSERTION(aBox->GetXULLayoutManager() == this, "setting incorrect box");
+
+  nsresult rv = nsStackLayout::XULLayout(aBox, aBoxLayoutState);
+#ifdef DEBUG_grid
+  mGrid.PrintCellMap();
+#endif
+  return rv;
+}
+
+void
+nsGridLayout2::IntrinsicISizesDirty(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  nsStackLayout::IntrinsicISizesDirty(aBox, aBoxLayoutState);
+  // XXXldb We really don't need to do all the work that NeedsRebuild
+  // does; we just need to mark intrinsic widths dirty on the
+  // (row/column)(s/-groups).
+  mGrid.NeedsRebuild(aBoxLayoutState);
+}
+
+nsGrid*
+nsGridLayout2::GetGrid(nsIFrame* aBox, int32_t* aIndex, nsGridRowLayout* aRequestor)
+{
+  // XXX This should be set a better way!
+  mGrid.SetBox(aBox);
+  NS_ASSERTION(aBox->GetXULLayoutManager() == this, "setting incorrect box");
+  return &mGrid;
+}
+
+void
+nsGridLayout2::AddWidth(nsSize& aSize, nscoord aSize2, bool aIsHorizontal)
+{
+  nscoord& size = GET_WIDTH(aSize, aIsHorizontal);
+
+  if (size != NS_INTRINSICSIZE) {
+    if (aSize2 == NS_INTRINSICSIZE)
+      size = NS_INTRINSICSIZE;
+    else
+      size += aSize2;
+  }
+}
+
+nsSize
+nsGridLayout2::GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  nsSize minSize = nsStackLayout::GetXULMinSize(aBox, aState); 
+
+  // if there are no <rows> tags that will sum up our columns,
+  // sum up our columns here.
+  nsSize total(0,0);
+  nsIFrame* rowsBox = mGrid.GetRowsBox();
+  nsIFrame* columnsBox = mGrid.GetColumnsBox();
+  if (!rowsBox || !columnsBox) {
+    if (!rowsBox) {
+      // max height is the sum of our rows
+      int32_t rows = mGrid.GetRowCount();
+      for (int32_t i=0; i < rows; i++)
+      {
+        nscoord height = mGrid.GetMinRowHeight(aState, i, true); 
+        AddWidth(total, height, false); // AddHeight
+      }
+    }
+
+    if (!columnsBox) {
+      // max height is the sum of our rows
+      int32_t columns = mGrid.GetColumnCount();
+      for (int32_t i=0; i < columns; i++)
+      {
+        nscoord width = mGrid.GetMinRowHeight(aState, i, false); 
+        AddWidth(total, width, true); // AddWidth
+      }
+    }
+
+    AddMargin(aBox, total);
+    AddOffset(aBox, total);
+    AddLargestSize(minSize, total);
+  }
+  
+  return minSize;
+}
+
+nsSize
+nsGridLayout2::GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  nsSize pref = nsStackLayout::GetXULPrefSize(aBox, aState); 
+
+  // if there are no <rows> tags that will sum up our columns,
+  // sum up our columns here.
+  nsSize total(0,0);
+  nsIFrame* rowsBox = mGrid.GetRowsBox();
+  nsIFrame* columnsBox = mGrid.GetColumnsBox();
+  if (!rowsBox || !columnsBox) {
+    if (!rowsBox) {
+      // max height is the sum of our rows
+      int32_t rows = mGrid.GetRowCount();
+      for (int32_t i=0; i < rows; i++)
+      {
+        nscoord height = mGrid.GetPrefRowHeight(aState, i, true); 
+        AddWidth(total, height, false); // AddHeight
+      }
+    }
+
+    if (!columnsBox) {
+      // max height is the sum of our rows
+      int32_t columns = mGrid.GetColumnCount();
+      for (int32_t i=0; i < columns; i++)
+      {
+        nscoord width = mGrid.GetPrefRowHeight(aState, i, false);
+        AddWidth(total, width, true); // AddWidth
+      }
+    }
+
+    AddMargin(aBox, total);
+    AddOffset(aBox, total);
+    AddLargestSize(pref, total);
+  }
+
+  return pref;
+}
+
+nsSize
+nsGridLayout2::GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  nsSize maxSize = nsStackLayout::GetXULMaxSize(aBox, aState); 
+
+  // if there are no <rows> tags that will sum up our columns,
+  // sum up our columns here.
+  nsSize total(NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+  nsIFrame* rowsBox = mGrid.GetRowsBox();
+  nsIFrame* columnsBox = mGrid.GetColumnsBox();
+  if (!rowsBox || !columnsBox) {
+    if (!rowsBox) {
+      total.height = 0;
+      // max height is the sum of our rows
+      int32_t rows = mGrid.GetRowCount();
+      for (int32_t i=0; i < rows; i++)
+      {
+        nscoord height = mGrid.GetMaxRowHeight(aState, i, true); 
+        AddWidth(total, height, false); // AddHeight
+      }
+    }
+
+    if (!columnsBox) {
+      total.width = 0;
+      // max height is the sum of our rows
+      int32_t columns = mGrid.GetColumnCount();
+      for (int32_t i=0; i < columns; i++)
+      {
+        nscoord width = mGrid.GetMaxRowHeight(aState, i, false);
+        AddWidth(total, width, true); // AddWidth
+      }
+    }
+
+    AddMargin(aBox, total);
+    AddOffset(aBox, total);
+    AddSmallestSize(maxSize, total);
+  }
+
+  return maxSize;
+}
+
+int32_t
+nsGridLayout2::BuildRows(nsIFrame* aBox, nsGridRow* aRows)
+{
+  if (aBox) {
+    aRows[0].Init(aBox, true);
+    return 1;
+  }
+  return 0;
+}
+
+nsMargin
+nsGridLayout2::GetTotalMargin(nsIFrame* aBox, bool aIsHorizontal)
+{
+  nsMargin margin(0,0,0,0);
+  return margin;
+}
+
+void
+nsGridLayout2::ChildrenInserted(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                nsIFrame* aPrevBox,
+                                const nsFrameList::Slice& aNewChildren)
+{
+  mGrid.NeedsRebuild(aState);
+}
+
+void
+nsGridLayout2::ChildrenAppended(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                const nsFrameList::Slice& aNewChildren)
+{
+  mGrid.NeedsRebuild(aState);
+}
+
+void
+nsGridLayout2::ChildrenRemoved(nsIFrame* aBox, nsBoxLayoutState& aState,
+                               nsIFrame* aChildList)
+{
+  mGrid.NeedsRebuild(aState);
+}
+
+void
+nsGridLayout2::ChildrenSet(nsIFrame* aBox, nsBoxLayoutState& aState,
+                           nsIFrame* aChildList)
+{
+  mGrid.NeedsRebuild(aState);
+}
+
+NS_IMPL_ADDREF_INHERITED(nsGridLayout2, nsStackLayout)
+NS_IMPL_RELEASE_INHERITED(nsGridLayout2, nsStackLayout)
+
+NS_INTERFACE_MAP_BEGIN(nsGridLayout2)
+  NS_INTERFACE_MAP_ENTRY(nsIGridPart)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIGridPart)
+NS_INTERFACE_MAP_END_INHERITING(nsStackLayout)
diff --git a/layout/xul/grid/nsGridLayout2.h b/layout/xul/grid/nsGridLayout2.h
new file mode 100644
index 0000000000..eb696faf8b
--- /dev/null
+++ b/layout/xul/grid/nsGridLayout2.h
@@ -0,0 +1,78 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsGridLayout2_h___
+#define nsGridLayout2_h___
+
+#include "mozilla/Attributes.h"
+#include "nsStackLayout.h"
+#include "nsIGridPart.h"
+#include "nsCoord.h"
+#include "nsGrid.h"
+
+class nsGridRowGroupLayout;
+class nsGridRowLayout;
+class nsGridRow;
+class nsBoxLayoutState;
+
+/**
+ * The nsBoxLayout implementation for a grid.
+ */
+class nsGridLayout2 final : public nsStackLayout, 
+                            public nsIGridPart
+{
+public:
+
+  friend nsresult NS_NewGridLayout2(nsIPresShell* aPresShell, nsBoxLayout** aNewLayout);
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+  NS_IMETHOD XULLayout(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual void IntrinsicISizesDirty(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+
+  virtual nsGridRowGroupLayout* CastToRowGroupLayout() override { return nullptr; }
+  virtual nsGridLayout2* CastToGridLayout() override { return this; }
+  virtual nsGrid* GetGrid(nsIFrame* aBox, int32_t* aIndex, nsGridRowLayout* aRequestor=nullptr) override;
+  virtual nsIGridPart* GetParentGridPart(nsIFrame* aBox, nsIFrame** aParentBox) override {
+    NS_NOTREACHED("Should not be called"); return nullptr;
+  }
+  virtual nsSize GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual void CountRowsColumns(nsIFrame* aBox, int32_t& aRowCount, int32_t& aComputedColumnCount) override { aRowCount++; }
+  virtual void DirtyRows(nsIFrame* aBox, nsBoxLayoutState& aState) override { }
+  virtual int32_t BuildRows(nsIFrame* aBox, nsGridRow* aRows) override;
+  virtual nsMargin GetTotalMargin(nsIFrame* aBox, bool aIsHorizontal) override;
+  virtual Type GetType() override { return eGrid; }
+  virtual void ChildrenInserted(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                nsIFrame* aPrevBox,
+                                const nsFrameList::Slice& aNewChildren) override;
+  virtual void ChildrenAppended(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                const nsFrameList::Slice& aNewChildren) override;
+  virtual void ChildrenRemoved(nsIFrame* aBox, nsBoxLayoutState& aState,
+                               nsIFrame* aChildList) override;
+  virtual void ChildrenSet(nsIFrame* aBox, nsBoxLayoutState& aState,
+                           nsIFrame* aChildList) override;
+
+  virtual nsIGridPart* AsGridPart() override { return this; }
+
+  static void AddOffset(nsIFrame* aChild, nsSize& aSize);
+
+protected:
+
+  explicit nsGridLayout2(nsIPresShell* aShell);
+  virtual ~nsGridLayout2();
+  nsGrid mGrid;
+
+private:
+  void AddWidth(nsSize& aSize, nscoord aSize2, bool aIsHorizontal);
+
+
+}; // class nsGridLayout2
+
+
+#endif
+
diff --git a/layout/xul/grid/nsGridRow.cpp b/layout/xul/grid/nsGridRow.cpp
new file mode 100644
index 0000000000..2a2a640168
--- /dev/null
+++ b/layout/xul/grid/nsGridRow.cpp
@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsGridRow.h"
+#include "nsBoxLayoutState.h"
+#include "nsIFrame.h"
+
+nsGridRow::nsGridRow():mIsBogus(false),
+                       mBox(nullptr), 
+                       mFlex(-1),
+                       mPref(-1),
+                       mMin(-1),
+                       mMax(-1),
+                       mTop(-1),
+                       mBottom(-1), 
+                       mTopMargin(0),
+                       mBottomMargin(0)
+
+{
+    MOZ_COUNT_CTOR(nsGridRow);
+}
+
+void
+nsGridRow::Init(nsIFrame* aBox, bool aIsBogus)
+{
+  mBox = aBox;
+  mIsBogus = aIsBogus;
+  mFlex = -1;
+  mPref = -1;
+  mMin = -1;
+  mMax = -1;
+  mTop = -1;
+  mBottom = -1;
+  mTopMargin = 0;
+  mBottomMargin = 0;
+}
+
+nsGridRow::~nsGridRow()
+{
+   MOZ_COUNT_DTOR(nsGridRow);
+}
+
+bool 
+nsGridRow::IsXULCollapsed()
+{
+  return mBox && mBox->IsXULCollapsed();
+}
+
diff --git a/layout/xul/grid/nsGridRow.h b/layout/xul/grid/nsGridRow.h
new file mode 100644
index 0000000000..a5bc391589
--- /dev/null
+++ b/layout/xul/grid/nsGridRow.h
@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ 
+  Author:
+  Eric D Vaughan
+
+**/
+
+#ifndef nsGridRow_h___
+#define nsGridRow_h___
+
+#include "nsCoord.h"
+
+class nsIFrame;
+
+/**
+ * The row (or column) data structure in the grid cellmap.
+ */
+class nsGridRow
+{
+public:
+   nsGridRow();
+   ~nsGridRow();
+
+   void Init(nsIFrame* aBox, bool aIsBogus);
+
+// accessors
+   nsIFrame* GetBox()   { return mBox;          }
+   bool IsPrefSet() { return (mPref != -1); }
+   bool IsMinSet()  { return (mMin  != -1); }
+   bool IsMaxSet()  { return (mMax  != -1); } 
+   bool IsFlexSet() { return (mFlex != -1); }
+   bool IsOffsetSet() { return (mTop != -1 && mBottom != -1); }
+   bool IsXULCollapsed();
+
+public:
+
+   bool    mIsBogus;
+   nsIFrame* mBox;
+   nscoord mFlex;
+   nscoord mPref;
+   nscoord mMin;
+   nscoord mMax;
+   nscoord mTop;
+   nscoord mBottom;
+   nscoord mTopMargin;
+   nscoord mBottomMargin;
+
+};
+
+
+#endif
+
diff --git a/layout/xul/grid/nsGridRowGroupFrame.cpp b/layout/xul/grid/nsGridRowGroupFrame.cpp
new file mode 100644
index 0000000000..5b72d3753f
--- /dev/null
+++ b/layout/xul/grid/nsGridRowGroupFrame.cpp
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsGridRowGroupFrame.h"
+#include "nsGridRowLeafLayout.h"
+#include "nsGridRow.h"
+#include "nsBoxLayoutState.h"
+#include "nsGridLayout2.h"
+
+already_AddRefed<nsBoxLayout> NS_NewGridRowGroupLayout();
+
+nsIFrame*
+NS_NewGridRowGroupFrame(nsIPresShell* aPresShell,
+                        nsStyleContext* aContext)
+{
+  nsCOMPtr<nsBoxLayout> layout = NS_NewGridRowGroupLayout();
+  return new (aPresShell) nsGridRowGroupFrame(aContext, layout);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsGridRowGroupFrame)
+
+
+/**
+ * This is redefined because row groups have a funny property. If they are flexible
+ * then their flex must be equal to the sum of their children's flexes.
+ */
+nscoord
+nsGridRowGroupFrame::GetXULFlex()
+{
+  // if we are flexible out flexibility is determined by our columns.
+  // so first get the our flex. If not 0 then our flex is the sum of
+  // our columns flexes.
+
+  if (!DoesNeedRecalc(mFlex))
+     return mFlex;
+
+  if (nsBoxFrame::GetXULFlex() == 0)
+    return 0;
+
+  // ok we are flexible add up our children
+  nscoord totalFlex = 0;
+  nsIFrame* child = nsBox::GetChildXULBox(this);
+  while (child)
+  {
+    totalFlex += child->GetXULFlex();
+    child = GetNextXULBox(child);
+  }
+
+  mFlex = totalFlex;
+
+  return totalFlex;
+}
+
+
diff --git a/layout/xul/grid/nsGridRowGroupFrame.h b/layout/xul/grid/nsGridRowGroupFrame.h
new file mode 100644
index 0000000000..f367e21216
--- /dev/null
+++ b/layout/xul/grid/nsGridRowGroupFrame.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+
+  Eric D Vaughan
+  A frame that can have multiple children. Only one child may be displayed at one time. So the
+  can be flipped though like a deck of cards.
+ 
+**/
+
+#ifndef nsGridRowGroupFrame_h___
+#define nsGridRowGroupFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+/**
+ * A frame representing a grid row (or column) group, which is usually
+ * an element that is a child of a grid and contains all the rows (or
+ * all the columns).  However, multiple levels of groups are allowed, so
+ * the parent or child could instead be another group.
+ */
+class nsGridRowGroupFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override
+  {
+      return MakeFrameName(NS_LITERAL_STRING("nsGridRowGroup"), aResult);
+  }
+#endif
+
+  nsGridRowGroupFrame(nsStyleContext* aContext,
+                      nsBoxLayout* aLayoutManager):
+    nsBoxFrame(aContext, false, aLayoutManager) {}
+
+  virtual nscoord GetXULFlex() override;
+
+}; // class nsGridRowGroupFrame
+
+
+
+#endif
+
diff --git a/layout/xul/grid/nsGridRowGroupLayout.cpp b/layout/xul/grid/nsGridRowGroupLayout.cpp
new file mode 100644
index 0000000000..1c600cef59
--- /dev/null
+++ b/layout/xul/grid/nsGridRowGroupLayout.cpp
@@ -0,0 +1,265 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+
+/*
+ * The nsGridRowGroupLayout implements the <rows> or <columns> tag in a grid. 
+ */
+
+#include "nsGridRowGroupLayout.h"
+#include "nsCOMPtr.h"
+#include "nsIScrollableFrame.h"
+#include "nsBox.h"
+#include "nsBoxLayoutState.h"
+#include "nsGridLayout2.h"
+#include "nsGridRow.h"
+#include "mozilla/ReflowInput.h"
+
+already_AddRefed<nsBoxLayout> NS_NewGridRowGroupLayout()
+{
+  RefPtr<nsBoxLayout> layout = new nsGridRowGroupLayout();
+  return layout.forget();
+} 
+
+nsGridRowGroupLayout::nsGridRowGroupLayout():nsGridRowLayout(), mRowCount(0)
+{
+}
+
+nsGridRowGroupLayout::~nsGridRowGroupLayout()
+{
+}
+
+void
+nsGridRowGroupLayout::ChildAddedOrRemoved(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  int32_t index = 0;
+  nsGrid* grid = GetGrid(aBox, &index);
+  bool isHorizontal = IsXULHorizontal(aBox);
+
+  if (grid)
+    grid->RowAddedOrRemoved(aState, index, isHorizontal);
+}
+
+void
+nsGridRowGroupLayout::AddWidth(nsSize& aSize, nscoord aSize2, bool aIsHorizontal)
+{
+  nscoord& size = GET_WIDTH(aSize, aIsHorizontal);
+
+  if (size == NS_INTRINSICSIZE || aSize2 == NS_INTRINSICSIZE)
+    size = NS_INTRINSICSIZE;
+  else
+    size += aSize2;
+}
+
+nsSize
+nsGridRowGroupLayout::GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{ 
+  nsSize vpref = nsGridRowLayout::GetXULPrefSize(aBox, aState); 
+
+
+ /* It is possible that we could have some extra columns. This is when less columns in XUL were 
+  * defined that needed. And example might be a grid with 3 defined columns but a row with 4 cells in 
+  * it. We would need an extra column to make the grid work. But because that extra column does not 
+  * have a box associated with it we must add its size in manually. Remember we could have extra rows
+  * as well.
+  */
+
+  int32_t index = 0;
+  nsGrid* grid = GetGrid(aBox, &index);
+
+  if (grid) 
+  {
+    // make sure we add in extra columns sizes as well
+    bool isHorizontal = IsXULHorizontal(aBox);
+    int32_t extraColumns = grid->GetExtraColumnCount(isHorizontal);
+    int32_t start = grid->GetColumnCount(isHorizontal) - grid->GetExtraColumnCount(isHorizontal);
+    for (int32_t i=0; i < extraColumns; i++)
+    {
+      nscoord pref =
+        grid->GetPrefRowHeight(aState, i+start, !isHorizontal); // GetPrefColumnWidth
+
+      AddWidth(vpref, pref, isHorizontal);
+    }
+  }
+
+  return vpref;
+}
+
+nsSize
+nsGridRowGroupLayout::GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+ nsSize maxSize = nsGridRowLayout::GetXULMaxSize(aBox, aState); 
+
+  int32_t index = 0;
+  nsGrid* grid = GetGrid(aBox, &index);
+
+  if (grid) 
+  {
+    // make sure we add in extra columns sizes as well
+    bool isHorizontal = IsXULHorizontal(aBox);
+    int32_t extraColumns = grid->GetExtraColumnCount(isHorizontal);
+    int32_t start = grid->GetColumnCount(isHorizontal) - grid->GetExtraColumnCount(isHorizontal);
+    for (int32_t i=0; i < extraColumns; i++)
+    {
+      nscoord max =
+        grid->GetMaxRowHeight(aState, i+start, !isHorizontal); // GetMaxColumnWidth
+
+      AddWidth(maxSize, max, isHorizontal);
+    }
+  }
+
+  return maxSize;
+}
+
+nsSize
+nsGridRowGroupLayout::GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  nsSize minSize = nsGridRowLayout::GetXULMinSize(aBox, aState); 
+
+  int32_t index = 0;
+  nsGrid* grid = GetGrid(aBox, &index);
+
+  if (grid) 
+  {
+    // make sure we add in extra columns sizes as well
+    bool isHorizontal = IsXULHorizontal(aBox);
+    int32_t extraColumns = grid->GetExtraColumnCount(isHorizontal);
+    int32_t start = grid->GetColumnCount(isHorizontal) - grid->GetExtraColumnCount(isHorizontal);
+    for (int32_t i=0; i < extraColumns; i++)
+    {
+      nscoord min = 
+        grid->GetMinRowHeight(aState, i+start, !isHorizontal); // GetMinColumnWidth
+      AddWidth(minSize, min, isHorizontal);
+    }
+  }
+
+  return minSize;
+}
+
+/*
+ * Run down through our children dirtying them recursively.
+ */
+void
+nsGridRowGroupLayout::DirtyRows(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  if (aBox) {
+    // mark us dirty
+    // XXXldb We probably don't want to walk up the ancestor chain
+    // calling MarkIntrinsicISizesDirty for every row group.
+    aState.PresShell()->FrameNeedsReflow(aBox, nsIPresShell::eTreeChange,
+                                         NS_FRAME_IS_DIRTY);
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+
+    while(child) {
+
+      // walk into scrollframes
+      nsIFrame* deepChild = nsGrid::GetScrolledBox(child);
+
+      // walk into other monuments
+      nsIGridPart* monument = nsGrid::GetPartFromBox(deepChild);
+      if (monument) 
+        monument->DirtyRows(deepChild, aState);
+
+      child = nsBox::GetNextXULBox(child);
+    }
+  }
+}
+
+
+void
+nsGridRowGroupLayout::CountRowsColumns(nsIFrame* aBox, int32_t& aRowCount, int32_t& aComputedColumnCount)
+{
+  if (aBox) {
+    int32_t startCount = aRowCount;
+
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+
+    while(child) {
+      
+      // first see if it is a scrollframe. If so walk down into it and get the scrolled child
+      nsIFrame* deepChild = nsGrid::GetScrolledBox(child);
+
+      nsIGridPart* monument = nsGrid::GetPartFromBox(deepChild);
+      if (monument) {
+        monument->CountRowsColumns(deepChild, aRowCount, aComputedColumnCount);
+        child = nsBox::GetNextXULBox(child);
+        deepChild = child;
+        continue;
+      }
+
+      child = nsBox::GetNextXULBox(child);
+
+      // if not a monument. Then count it. It will be a bogus row
+      aRowCount++;
+    }
+
+    mRowCount = aRowCount - startCount;
+  }
+}
+
+
+/**
+ * Fill out the given row structure recursively
+ */
+int32_t 
+nsGridRowGroupLayout::BuildRows(nsIFrame* aBox, nsGridRow* aRows)
+{ 
+  int32_t rowCount = 0;
+
+  if (aBox) {
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+
+    while(child) {
+      
+      // first see if it is a scrollframe. If so walk down into it and get the scrolled child
+      nsIFrame* deepChild = nsGrid::GetScrolledBox(child);
+
+      nsIGridPart* monument = nsGrid::GetPartFromBox(deepChild);
+      if (monument) {
+        rowCount += monument->BuildRows(deepChild, &aRows[rowCount]);
+        child = nsBox::GetNextXULBox(child);
+        deepChild = child;
+        continue;
+      }
+
+      aRows[rowCount].Init(child, true);
+
+      child = nsBox::GetNextXULBox(child);
+
+      // if not a monument. Then count it. It will be a bogus row
+      rowCount++;
+    }
+  }
+
+  return rowCount;
+}
+
+nsMargin
+nsGridRowGroupLayout::GetTotalMargin(nsIFrame* aBox, bool aIsHorizontal)
+{
+  // group have border and padding added to the total margin
+
+  nsMargin margin = nsGridRowLayout::GetTotalMargin(aBox, aIsHorizontal);
+  
+  // make sure we have the scrollframe on the outside if it has one.
+  // that's where the border is.
+  aBox = nsGrid::GetScrollBox(aBox);
+
+  // add our border/padding to it
+  nsMargin borderPadding(0,0,0,0);
+  aBox->GetXULBorderAndPadding(borderPadding);
+  margin += borderPadding;
+
+  return margin;
+}
+
+
diff --git a/layout/xul/grid/nsGridRowGroupLayout.h b/layout/xul/grid/nsGridRowGroupLayout.h
new file mode 100644
index 0000000000..07f2aa1eb5
--- /dev/null
+++ b/layout/xul/grid/nsGridRowGroupLayout.h
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ 
+  Author:
+  Eric D Vaughan
+
+**/
+
+#ifndef nsGridRowGroupLayout_h___
+#define nsGridRowGroupLayout_h___
+
+#include "mozilla/Attributes.h"
+#include "nsGridRowLayout.h"
+
+/**
+ * The nsBoxLayout implementation for nsGridRowGroupFrame.
+ */
+class nsGridRowGroupLayout : public nsGridRowLayout
+{
+public:
+
+  friend already_AddRefed<nsBoxLayout> NS_NewGridRowGroupLayout();
+
+  virtual nsGridRowGroupLayout* CastToRowGroupLayout() override { return this; }
+  virtual nsSize GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual void CountRowsColumns(nsIFrame* aBox, int32_t& aRowCount, int32_t& aComputedColumnCount) override;
+  virtual void DirtyRows(nsIFrame* aBox, nsBoxLayoutState& aState) override;
+  virtual int32_t BuildRows(nsIFrame* aBox, nsGridRow* aRows) override;
+  virtual nsMargin GetTotalMargin(nsIFrame* aBox, bool aIsHorizontal) override;
+  virtual int32_t GetRowCount() override { return mRowCount; }
+  virtual Type GetType() override { return eRowGroup; }
+
+protected:
+  nsGridRowGroupLayout();
+  virtual ~nsGridRowGroupLayout();
+
+  virtual void ChildAddedOrRemoved(nsIFrame* aBox, nsBoxLayoutState& aState) override;
+  static void AddWidth(nsSize& aSize, nscoord aSize2, bool aIsHorizontal);
+
+private:
+  int32_t mRowCount;
+};
+
+#endif
+
diff --git a/layout/xul/grid/nsGridRowLayout.cpp b/layout/xul/grid/nsGridRowLayout.cpp
new file mode 100644
index 0000000000..a658e088e2
--- /dev/null
+++ b/layout/xul/grid/nsGridRowLayout.cpp
@@ -0,0 +1,197 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsGridRowLayout.h"
+#include "nsBoxLayoutState.h"
+#include "nsIScrollableFrame.h"
+#include "nsBox.h"
+#include "nsStackLayout.h"
+#include "nsGrid.h"
+
+nsGridRowLayout::nsGridRowLayout():nsSprocketLayout()
+{
+}
+
+nsGridRowLayout::~nsGridRowLayout()
+{
+}
+
+void
+nsGridRowLayout::ChildrenInserted(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                  nsIFrame* aPrevBox,
+                                  const nsFrameList::Slice& aNewChildren)
+{
+  ChildAddedOrRemoved(aBox, aState);
+}
+
+void
+nsGridRowLayout::ChildrenAppended(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                  const nsFrameList::Slice& aNewChildren)
+{
+  ChildAddedOrRemoved(aBox, aState);
+}
+
+void
+nsGridRowLayout::ChildrenRemoved(nsIFrame* aBox, nsBoxLayoutState& aState, nsIFrame* aChildList)
+{
+  ChildAddedOrRemoved(aBox, aState);
+}
+
+void
+nsGridRowLayout::ChildrenSet(nsIFrame* aBox, nsBoxLayoutState& aState, nsIFrame* aChildList)
+{
+  ChildAddedOrRemoved(aBox, aState);
+}
+
+nsIGridPart*
+nsGridRowLayout::GetParentGridPart(nsIFrame* aBox, nsIFrame** aParentBox)
+{
+  // go up and find our parent gridRow. Skip and non gridRow
+  // parents.
+  *aParentBox = nullptr;
+  
+  // walk up through any scrollboxes
+  aBox = nsGrid::GetScrollBox(aBox);
+
+  // get the parent
+  if (aBox)
+    aBox = nsBox::GetParentXULBox(aBox);
+
+  if (aBox)
+  {
+    nsIGridPart* parentGridRow = nsGrid::GetPartFromBox(aBox);
+    if (parentGridRow && parentGridRow->CanContain(this)) {
+      *aParentBox = aBox;
+      return parentGridRow;
+    }
+  }
+
+  return nullptr;
+}
+
+
+nsGrid*
+nsGridRowLayout::GetGrid(nsIFrame* aBox, int32_t* aIndex, nsGridRowLayout* aRequestor)
+{
+
+   if (aRequestor == nullptr)
+   {
+      nsIFrame* parentBox; // nsIFrame is implemented by nsIFrame and is not refcounted.
+      nsIGridPart* parent = GetParentGridPart(aBox, &parentBox);
+      if (parent)
+         return parent->GetGrid(parentBox, aIndex, this);
+      return nullptr;
+   }
+
+   int32_t index = -1;
+   nsIFrame* child = nsBox::GetChildXULBox(aBox);
+   int32_t count = 0;
+   while(child)
+   {
+     // if there is a scrollframe walk inside it to its child
+     nsIFrame* childBox = nsGrid::GetScrolledBox(child);
+
+     nsBoxLayout* layout = childBox->GetXULLayoutManager();
+     nsIGridPart* gridRow = nsGrid::GetPartFromBox(childBox);
+     if (gridRow) 
+     {
+       if (layout == aRequestor) {
+          index = count;
+          break;
+       }
+       count += gridRow->GetRowCount();
+     } else 
+       count++;
+
+     child = nsBox::GetNextXULBox(child);
+   }
+
+   // if we didn't find ourselves then the tree isn't properly formed yet
+   // this could happen during initial construction so lets just
+   // fail.
+   if (index == -1) {
+     *aIndex = -1;
+     return nullptr;
+   }
+
+   (*aIndex) += index;
+
+   nsIFrame* parentBox; // nsIFrame is implemented by nsIFrame and is not refcounted.
+   nsIGridPart* parent = GetParentGridPart(aBox, &parentBox);
+   if (parent)
+     return parent->GetGrid(parentBox, aIndex, this);
+
+   return nullptr;
+}
+
+nsMargin
+nsGridRowLayout::GetTotalMargin(nsIFrame* aBox, bool aIsHorizontal)
+{
+  // get our parents margin
+  nsMargin margin(0,0,0,0);
+  nsIFrame* parent = nullptr;
+  nsIGridPart* part = GetParentGridPart(aBox, &parent);
+  if (part && parent) {
+    // if we are the first or last child walk upward and add margins.
+
+    // make sure we check for a scrollbox
+    aBox = nsGrid::GetScrollBox(aBox);
+
+    // see if we have a next to see if we are last
+    nsIFrame* next = nsBox::GetNextXULBox(aBox);
+
+    // get the parent first child to see if we are first
+    nsIFrame* child = nsBox::GetChildXULBox(parent);
+
+    margin = part->GetTotalMargin(parent, aIsHorizontal);
+
+    // if first or last
+    if (child == aBox || next == nullptr) {
+
+       // if it's not the first child remove the top margin
+       // we don't need it.
+       if (child != aBox)
+       {
+          if (aIsHorizontal)
+              margin.top = 0;
+          else 
+              margin.left = 0;
+       }
+
+       // if it's not the last child remove the bottom margin
+       // we don't need it.
+       if (next != nullptr)
+       {
+          if (aIsHorizontal)
+              margin.bottom = 0;
+          else 
+              margin.right = 0;
+       }
+
+    }
+  }
+    
+  // add ours to it.
+  nsMargin ourMargin;
+  aBox->GetXULMargin(ourMargin);
+  margin += ourMargin;
+
+  return margin;
+}
+
+NS_IMPL_ADDREF_INHERITED(nsGridRowLayout, nsBoxLayout)
+NS_IMPL_RELEASE_INHERITED(nsGridRowLayout, nsBoxLayout)
+
+NS_INTERFACE_MAP_BEGIN(nsGridRowLayout)
+  NS_INTERFACE_MAP_ENTRY(nsIGridPart)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIGridPart)
+NS_INTERFACE_MAP_END_INHERITING(nsBoxLayout)
diff --git a/layout/xul/grid/nsGridRowLayout.h b/layout/xul/grid/nsGridRowLayout.h
new file mode 100644
index 0000000000..22a6f12c93
--- /dev/null
+++ b/layout/xul/grid/nsGridRowLayout.h
@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ 
+  Author:
+  Eric D Vaughan
+
+**/
+
+#ifndef nsGridRowLayout_h___
+#define nsGridRowLayout_h___
+
+#include "mozilla/Attributes.h"
+#include "nsSprocketLayout.h"
+#include "nsIGridPart.h"
+class nsGridRowGroupLayout;
+class nsGridLayout2;
+class nsBoxLayoutState;
+class nsGrid;
+
+/**
+ * A common base class for nsGridRowLeafLayout (the nsBoxLayout object
+ * for a grid row or column) and nsGridRowGroupLayout (the nsBoxLayout
+ * object for a grid row group or column group).
+ */
+// XXXldb This needs a name that indicates that it's a base class for
+// both row and rows (row-group).
+class nsGridRowLayout : public nsSprocketLayout,
+                        public nsIGridPart
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  virtual nsGridRowGroupLayout* CastToRowGroupLayout() override { return nullptr; }
+  virtual nsGridLayout2* CastToGridLayout() override { return nullptr; }
+  virtual nsGrid* GetGrid(nsIFrame* aBox, int32_t* aIndex, nsGridRowLayout* aRequestor=nullptr) override;
+  virtual nsIGridPart* GetParentGridPart(nsIFrame* aBox, nsIFrame** aParentBox) override;
+  virtual void ChildrenInserted(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                nsIFrame* aPrevBox,
+                                const nsFrameList::Slice& aNewChildren) override;
+  virtual void ChildrenAppended(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                const nsFrameList::Slice& aNewChildren) override;
+  virtual void ChildrenRemoved(nsIFrame* aBox, nsBoxLayoutState& aState, nsIFrame* aChildList) override;
+  virtual void ChildrenSet(nsIFrame* aBox, nsBoxLayoutState& aState, nsIFrame* aChildList) override;
+  virtual nsMargin GetTotalMargin(nsIFrame* aBox, bool aIsHorizontal) override;
+
+  virtual nsIGridPart* AsGridPart() override { return this; }
+
+protected:
+  virtual void ChildAddedOrRemoved(nsIFrame* aBox, nsBoxLayoutState& aState)=0;
+
+  nsGridRowLayout();
+  virtual ~nsGridRowLayout();
+};
+
+#endif
+
diff --git a/layout/xul/grid/nsGridRowLeafFrame.cpp b/layout/xul/grid/nsGridRowLeafFrame.cpp
new file mode 100644
index 0000000000..e973877a40
--- /dev/null
+++ b/layout/xul/grid/nsGridRowLeafFrame.cpp
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsGridRowLeafFrame.h"
+#include "nsGridRowLeafLayout.h"
+#include "nsGridRow.h"
+#include "nsBoxLayoutState.h"
+#include "nsGridLayout2.h"
+
+already_AddRefed<nsBoxLayout> NS_NewGridRowLeafLayout();
+
+nsIFrame*
+NS_NewGridRowLeafFrame(nsIPresShell* aPresShell,
+                       nsStyleContext* aContext)
+{
+  nsCOMPtr<nsBoxLayout> layout = NS_NewGridRowLeafLayout();
+  return new (aPresShell) nsGridRowLeafFrame(aContext, false, layout);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsGridRowLeafFrame)
+
+/*
+ * Our border and padding could be affected by our columns or rows.
+ * Let's go check it out.
+ */
+nsresult
+nsGridRowLeafFrame::GetXULBorderAndPadding(nsMargin& aBorderAndPadding)
+{
+  // if our columns have made our padding larger add it in.
+  nsresult rv = nsBoxFrame::GetXULBorderAndPadding(aBorderAndPadding);
+
+  nsIGridPart* part = nsGrid::GetPartFromBox(this);
+  if (!part)
+    return rv;
+    
+  int32_t index = 0;
+  nsGrid* grid = part->GetGrid(this, &index);
+
+  if (!grid) 
+    return rv;
+
+  bool isHorizontal = IsXULHorizontal();
+
+  int32_t firstIndex = 0;
+  int32_t lastIndex = 0;
+  nsGridRow* firstRow = nullptr;
+  nsGridRow* lastRow = nullptr;
+  grid->GetFirstAndLastRow(firstIndex, lastIndex, firstRow, lastRow, isHorizontal);
+
+  // only the first and last rows can be affected.
+  if (firstRow && firstRow->GetBox() == this) {
+    
+    nscoord top = 0;
+    nscoord bottom = 0;
+    grid->GetRowOffsets(firstIndex, top, bottom, isHorizontal);
+
+    if (isHorizontal) {
+      if (top > aBorderAndPadding.top)
+        aBorderAndPadding.top = top;
+    } else {
+      if (top > aBorderAndPadding.left)
+        aBorderAndPadding.left = top;
+    } 
+  }
+
+  if (lastRow && lastRow->GetBox() == this) {
+    
+    nscoord top = 0;
+    nscoord bottom = 0;
+    grid->GetRowOffsets(lastIndex, top, bottom, isHorizontal);
+
+    if (isHorizontal) {
+      if (bottom > aBorderAndPadding.bottom)
+        aBorderAndPadding.bottom = bottom;
+    } else {
+      if (bottom > aBorderAndPadding.right)
+        aBorderAndPadding.right = bottom;
+    }
+    
+  }  
+  
+  return rv;
+}
+
+
diff --git a/layout/xul/grid/nsGridRowLeafFrame.h b/layout/xul/grid/nsGridRowLeafFrame.h
new file mode 100644
index 0000000000..dd4ee6835d
--- /dev/null
+++ b/layout/xul/grid/nsGridRowLeafFrame.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+
+  Eric D Vaughan
+  A frame that can have multiple children. Only one child may be displayed at one time. So the
+  can be flipped though like a deck of cards.
+ 
+**/
+
+#ifndef nsGridRowLeafFrame_h___
+#define nsGridRowLeafFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+/**
+ * A frame representing a grid row (or column).  Grid row (and column)
+ * elements are the children of row group (or column group) elements,
+ * and their children are placed one to a cell.
+ */
+// XXXldb This needs a better name that indicates that it's for any grid
+// row.
+class nsGridRowLeafFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewGridRowLeafFrame(nsIPresShell* aPresShell,
+                                          nsStyleContext* aContext);
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override
+  {
+      return MakeFrameName(NS_LITERAL_STRING("nsGridRowLeaf"), aResult);
+  }
+#endif
+
+  nsGridRowLeafFrame(nsStyleContext* aContext,
+                     bool aIsRoot,
+                     nsBoxLayout* aLayoutManager):
+    nsBoxFrame(aContext, aIsRoot, aLayoutManager) {}
+
+  virtual nsresult GetXULBorderAndPadding(nsMargin& aBorderAndPadding) override;
+
+}; // class nsGridRowLeafFrame
+
+
+
+#endif
+
diff --git a/layout/xul/grid/nsGridRowLeafLayout.cpp b/layout/xul/grid/nsGridRowLeafLayout.cpp
new file mode 100644
index 0000000000..2a089af0c8
--- /dev/null
+++ b/layout/xul/grid/nsGridRowLeafLayout.cpp
@@ -0,0 +1,328 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsGridRowLeafLayout.h"
+#include "nsGridRowGroupLayout.h"
+#include "nsGridRow.h"
+#include "nsBoxLayoutState.h"
+#include "nsBox.h"
+#include "nsIScrollableFrame.h"
+#include "nsBoxFrame.h"
+#include "nsGridLayout2.h"
+#include <algorithm>
+
+already_AddRefed<nsBoxLayout> NS_NewGridRowLeafLayout()
+{
+  RefPtr<nsBoxLayout> layout = new nsGridRowLeafLayout();
+  return layout.forget();
+} 
+
+nsGridRowLeafLayout::nsGridRowLeafLayout():nsGridRowLayout()
+{
+}
+
+nsGridRowLeafLayout::~nsGridRowLeafLayout()
+{
+}
+
+nsSize
+nsGridRowLeafLayout::GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  int32_t index = 0;
+  nsGrid* grid = GetGrid(aBox, &index);
+  bool isHorizontal = IsXULHorizontal(aBox);
+
+  // If we are not in a grid. Then we just work like a box. But if we are in a grid
+  // ask the grid for our size.
+  if (!grid) {
+    return nsGridRowLayout::GetXULPrefSize(aBox, aState); 
+  }
+  else {
+    return grid->GetPrefRowSize(aState, index, isHorizontal);
+    //AddBorderAndPadding(aBox, pref);
+  }
+}
+
+nsSize
+nsGridRowLeafLayout::GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  int32_t index = 0;
+  nsGrid* grid = GetGrid(aBox, &index);
+  bool isHorizontal = IsXULHorizontal(aBox);
+
+  if (!grid)
+    return nsGridRowLayout::GetXULMinSize(aBox, aState); 
+  else {
+    nsSize minSize = grid->GetMinRowSize(aState, index, isHorizontal);
+    AddBorderAndPadding(aBox, minSize);
+    return minSize;
+  }
+}
+
+nsSize
+nsGridRowLeafLayout::GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  int32_t index = 0;
+  nsGrid* grid = GetGrid(aBox, &index);
+  bool isHorizontal = IsXULHorizontal(aBox);
+
+  if (!grid)
+    return nsGridRowLayout::GetXULMaxSize(aBox, aState); 
+  else {
+    nsSize maxSize;
+    maxSize = grid->GetMaxRowSize(aState, index, isHorizontal);
+    AddBorderAndPadding(aBox, maxSize);
+    return maxSize;
+  }
+}
+
+/** If a child is added or removed or changes size
+  */
+void
+nsGridRowLeafLayout::ChildAddedOrRemoved(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  int32_t index = 0;
+  nsGrid* grid = GetGrid(aBox, &index);
+  bool isHorizontal = IsXULHorizontal(aBox);
+
+  if (grid)
+    grid->CellAddedOrRemoved(aState, index, isHorizontal);
+}
+
+void
+nsGridRowLeafLayout::PopulateBoxSizes(nsIFrame* aBox, nsBoxLayoutState& aState, nsBoxSize*& aBoxSizes, nscoord& aMinSize, nscoord& aMaxSize, int32_t& aFlexes)
+{
+  int32_t index = 0;
+  nsGrid* grid = GetGrid(aBox, &index);
+  bool isHorizontal = IsXULHorizontal(aBox);
+
+  // Our base class SprocketLayout is giving us a chance to change the box sizes before layout
+  // If we are a row lets change the sizes to match our columns. If we are a column then do the opposite
+  // and make them match or rows.
+  if (grid) {
+    nsGridRow* column;
+    int32_t count = grid->GetColumnCount(isHorizontal); 
+    nsBoxSize* start = nullptr;
+    nsBoxSize* last = nullptr;
+    nsBoxSize* current = nullptr;
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+    for (int i=0; i < count; i++)
+    {
+      column = grid->GetColumnAt(i,isHorizontal); 
+
+      // make sure the value was computed before we use it.
+      // !isHorizontal is passed in to invert the behavior of these methods.
+      nscoord pref =
+        grid->GetPrefRowHeight(aState, i, !isHorizontal); // GetPrefColumnWidth
+      nscoord min = 
+        grid->GetMinRowHeight(aState, i, !isHorizontal);  // GetMinColumnWidth
+      nscoord max = 
+        grid->GetMaxRowHeight(aState, i, !isHorizontal);  // GetMaxColumnWidth
+      nscoord flex = grid->GetRowFlex(i, !isHorizontal);  // GetColumnFlex
+      nscoord left  = 0;
+      nscoord right  = 0;
+      grid->GetRowOffsets(i, left, right, !isHorizontal); // GetColumnOffsets
+      nsIFrame* box = column->GetBox();
+      bool collapsed = false;
+      nscoord topMargin = column->mTopMargin;
+      nscoord bottomMargin = column->mBottomMargin;
+
+      if (box) 
+        collapsed = box->IsXULCollapsed();
+
+      pref = pref - (left + right);
+      if (pref < 0)
+        pref = 0;
+
+      // if this is the first or last column. Take into account that
+      // our row could have a border that could affect our left or right
+      // padding from our columns. If the row has padding subtract it.
+      // would should always be able to garentee that our margin is smaller
+      // or equal to our left or right
+      int32_t firstIndex = 0;
+      int32_t lastIndex = 0;
+      nsGridRow* firstRow = nullptr;
+      nsGridRow* lastRow = nullptr;
+      grid->GetFirstAndLastRow(firstIndex, lastIndex, firstRow, lastRow, !isHorizontal);
+
+      if (i == firstIndex || i == lastIndex) {
+        nsMargin offset = GetTotalMargin(aBox, isHorizontal);
+
+        nsMargin border(0,0,0,0);
+        // can't call GetBorderPadding we will get into recursion
+        aBox->GetXULBorder(border);
+        offset += border;
+        aBox->GetXULPadding(border);
+        offset += border;
+
+        // subtract from out left and right
+        if (i == firstIndex) 
+        {
+          if (isHorizontal)
+           left -= offset.left;
+          else
+           left -= offset.top;
+        }
+
+        if (i == lastIndex)
+        {
+          if (isHorizontal)
+           right -= offset.right;
+          else
+           right -= offset.bottom;
+        }
+      }
+    
+      // initialize the box size here 
+      max = std::max(min, max);
+      pref = nsBox::BoundsCheck(min, pref, max);
+   
+      current = new (aState) nsBoxSize();
+      current->pref = pref;
+      current->min = min;
+      current->max = max;
+      current->flex = flex;
+      current->bogus = column->mIsBogus;
+      current->left = left + topMargin;
+      current->right = right + bottomMargin;
+      current->collapsed = collapsed;
+
+      if (!start) {
+        start = current;
+        last = start;
+      } else {
+        last->next = current;
+        last = current;
+      }
+
+      if (child && !column->mIsBogus)
+        child = nsBox::GetNextXULBox(child);
+
+    }
+    aBoxSizes = start;
+  }
+
+  nsSprocketLayout::PopulateBoxSizes(aBox, aState, aBoxSizes, aMinSize, aMaxSize, aFlexes);
+}
+
+void
+nsGridRowLeafLayout::ComputeChildSizes(nsIFrame* aBox,
+                           nsBoxLayoutState& aState, 
+                           nscoord& aGivenSize, 
+                           nsBoxSize* aBoxSizes, 
+                           nsComputedBoxSize*& aComputedBoxSizes)
+{ 
+  // see if we are in a scrollable frame. If we are then there could be scrollbars present
+  // if so we need to subtract them out to make sure our columns line up.
+  if (aBox) {
+    bool isHorizontal = aBox->IsXULHorizontal();
+
+    // go up the parent chain looking for scrollframes
+    nscoord diff = 0;
+    nsIFrame* parentBox;
+    (void)GetParentGridPart(aBox, &parentBox);
+    while (parentBox) {
+      nsIFrame* scrollbox = nsGrid::GetScrollBox(parentBox);
+      nsIScrollableFrame *scrollable = do_QueryFrame(scrollbox);
+      if (scrollable) {
+        // Don't call GetActualScrollbarSizes here because it's not safe
+        // to call that while we're reflowing the contents of the scrollframe,
+        // which we are here.
+        nsMargin scrollbarSizes = scrollable->GetDesiredScrollbarSizes(&aState);
+        uint32_t visible = scrollable->GetScrollbarVisibility();
+
+        if (isHorizontal && (visible & nsIScrollableFrame::VERTICAL)) {
+          diff += scrollbarSizes.left + scrollbarSizes.right;
+        } else if (!isHorizontal && (visible & nsIScrollableFrame::HORIZONTAL)) {
+          diff += scrollbarSizes.top + scrollbarSizes.bottom;
+        }
+      }
+
+      (void)GetParentGridPart(parentBox, &parentBox);
+    }
+
+    if (diff > 0) {
+      aGivenSize += diff;
+
+      nsSprocketLayout::ComputeChildSizes(aBox, aState, aGivenSize, aBoxSizes, aComputedBoxSizes);
+
+      aGivenSize -= diff;
+
+      nsComputedBoxSize* s    = aComputedBoxSizes;
+      nsComputedBoxSize* last = aComputedBoxSizes;
+      while(s)
+      {
+        last = s;
+        s = s->next;
+      }
+  
+      if (last) 
+        last->size -= diff;                         
+
+      return;
+    }
+  }
+      
+  nsSprocketLayout::ComputeChildSizes(aBox, aState, aGivenSize, aBoxSizes, aComputedBoxSizes);
+
+}
+
+NS_IMETHODIMP
+nsGridRowLeafLayout::XULLayout(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  return nsGridRowLayout::XULLayout(aBox, aBoxLayoutState);
+}
+
+void
+nsGridRowLeafLayout::DirtyRows(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  if (aBox) {
+    // mark us dirty
+    // XXXldb We probably don't want to walk up the ancestor chain
+    // calling MarkIntrinsicISizesDirty for every row.
+    aState.PresShell()->FrameNeedsReflow(aBox, nsIPresShell::eTreeChange,
+                                         NS_FRAME_IS_DIRTY);
+  }
+}
+
+void
+nsGridRowLeafLayout::CountRowsColumns(nsIFrame* aBox, int32_t& aRowCount, int32_t& aComputedColumnCount)
+{
+  if (aBox) {
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+
+    // count the children
+    int32_t columnCount = 0;
+    while(child) {
+      child = nsBox::GetNextXULBox(child);
+      columnCount++;
+    }
+
+    // if our count is greater than the current column count
+    if (columnCount > aComputedColumnCount) 
+      aComputedColumnCount = columnCount;
+
+    aRowCount++;
+  }
+}
+
+int32_t
+nsGridRowLeafLayout::BuildRows(nsIFrame* aBox, nsGridRow* aRows)
+{
+  if (aBox) {
+      aRows[0].Init(aBox, false);
+      return 1;
+  }
+
+  return 0;
+}
+
diff --git a/layout/xul/grid/nsGridRowLeafLayout.h b/layout/xul/grid/nsGridRowLeafLayout.h
new file mode 100644
index 0000000000..b103ab176b
--- /dev/null
+++ b/layout/xul/grid/nsGridRowLeafLayout.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ 
+  Author:
+  Eric D Vaughan
+
+**/
+
+#ifndef nsGridRowLeafLayout_h___
+#define nsGridRowLeafLayout_h___
+
+#include "mozilla/Attributes.h"
+#include "nsGridRowLayout.h"
+#include "nsCOMPtr.h"
+
+/**
+ * The nsBoxLayout implementation for nsGridRowLeafFrame.
+ */
+// XXXldb This needs a better name that indicates that it's for any grid
+// row.
+class nsGridRowLeafLayout final : public nsGridRowLayout
+{
+public:
+
+  friend already_AddRefed<nsBoxLayout> NS_NewGridRowLeafLayout();
+
+  virtual nsSize GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual void ChildAddedOrRemoved(nsIFrame* aBox, nsBoxLayoutState& aState) override;
+  NS_IMETHOD XULLayout(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual void CountRowsColumns(nsIFrame* aBox, int32_t& aRowCount, int32_t& aComputedColumnCount) override;
+  virtual void DirtyRows(nsIFrame* aBox, nsBoxLayoutState& aState) override;
+  virtual int32_t BuildRows(nsIFrame* aBox, nsGridRow* aRows) override;
+  virtual Type GetType() override { return eRowLeaf; }
+
+protected:
+
+  virtual void PopulateBoxSizes(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState,
+                                nsBoxSize*& aBoxSizes, nscoord& aMinSize,
+                                nscoord& aMaxSize, int32_t& aFlexes) override;
+  virtual void ComputeChildSizes(nsIFrame* aBox,
+                                 nsBoxLayoutState& aState,
+                                 nscoord& aGivenSize,
+                                 nsBoxSize* aBoxSizes,
+                                 nsComputedBoxSize*& aComputedBoxSizes) override;
+
+
+  nsGridRowLeafLayout();
+  virtual ~nsGridRowLeafLayout();
+  //virtual void AddBorderAndPadding(nsIFrame* aBox, nsSize& aSize);
+
+private:
+
+}; // class nsGridRowLeafLayout
+
+#endif
+
diff --git a/layout/xul/grid/nsIGridPart.h b/layout/xul/grid/nsIGridPart.h
new file mode 100644
index 0000000000..202429de63
--- /dev/null
+++ b/layout/xul/grid/nsIGridPart.h
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIGridPart_h___
+#define nsIGridPart_h___
+
+#include "nsISupports.h"
+
+class nsGridRowGroupLayout;
+class nsGrid;
+class nsGridRowLayout;
+class nsGridRow;
+class nsGridLayout2;
+
+// 07373ed7-e947-4a5e-b36c-69f7c195677b
+#define NS_IGRIDPART_IID \
+{ 0x07373ed7, 0xe947, 0x4a5e, \
+  { 0xb3, 0x6c, 0x69, 0xf7, 0xc1, 0x95, 0x67, 0x7b } }
+
+/**
+ * An additional interface implemented by nsBoxLayout implementations
+ * for parts of a grid (excluding cells, which are not special).
+ */
+class nsIGridPart : public nsISupports {
+
+public:
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IGRIDPART_IID)
+
+  virtual nsGridRowGroupLayout* CastToRowGroupLayout()=0;
+  virtual nsGridLayout2* CastToGridLayout()=0;
+
+  /**
+   * @param aBox [IN] The other half of the |this| parameter, i.e., the box
+   *                  whose layout manager is |this|.
+   * @param aIndex [INOUT] For callers not setting aRequestor, the value
+   *                       pointed to by aIndex is incremented by the index
+   *                       of the row (aBox) within its row group; if aBox
+   *                       is not a row/column, it is untouched.
+   *                       The implementation does this by doing the aIndex
+   *                       incrementing in the call to the parent row group
+   *                       when aRequestor is non-null.
+   * @param aRequestor [IN] Non-null if and only if this is a recursive
+   *                   call from the GetGrid method on a child grid part,
+   *                   in which case it is a pointer to that grid part.
+   *                   (This may only be non-null for row groups and
+   *                   grids.)
+   * @return The grid of which aBox (a row, row group, or grid) is a part.
+   */
+  virtual nsGrid* GetGrid(nsIFrame* aBox, int32_t* aIndex, nsGridRowLayout* aRequestor=nullptr)=0;
+
+  /**
+   * @param aBox [IN] The other half of the |this| parameter, i.e., the box
+   *                  whose layout manager is |this|.
+   * @param aParentBox [OUT] The box representing the next level up in
+   *                   the grid (i.e., row group for a row, grid for a
+   *                   row group).
+   * @returns The layout manager for aParentBox.
+   */
+  virtual nsIGridPart* GetParentGridPart(nsIFrame* aBox, nsIFrame** aParentBox) = 0;
+
+  /**
+   * @param aBox [IN] The other half of the |this| parameter, i.e., the box
+   *                  whose layout manager is |this|.
+   * @param aRowCount [INOUT] Row count
+   * @param aComputedColumnCount [INOUT] Column count
+   */
+  virtual void CountRowsColumns(nsIFrame* aBox, int32_t& aRowCount, int32_t& aComputedColumnCount)=0;
+  virtual void DirtyRows(nsIFrame* aBox, nsBoxLayoutState& aState)=0;
+  virtual int32_t BuildRows(nsIFrame* aBox, nsGridRow* aRows)=0;
+  virtual nsMargin GetTotalMargin(nsIFrame* aBox, bool aIsHorizontal)=0;
+  virtual int32_t GetRowCount() { return 1; }
+  
+  /**
+   * Return the level of the grid hierarchy this grid part represents.
+   */
+  enum Type { eGrid, eRowGroup, eRowLeaf };
+  virtual Type GetType()=0;
+
+  /**
+   * Return whether this grid part is an appropriate parent for the argument.
+   */
+  bool CanContain(nsIGridPart* aPossibleChild) {
+    Type thisType = GetType(), childType = aPossibleChild->GetType();
+    return thisType + 1 == childType || (thisType == eRowGroup && childType == eRowGroup);
+  }
+
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsIGridPart, NS_IGRIDPART_IID)
+
+#endif
+
diff --git a/layout/xul/grid/reftests/column-sizing-1-ref.xul b/layout/xul/grid/reftests/column-sizing-1-ref.xul
new file mode 100644
index 0000000000..df0113083f
--- /dev/null
+++ b/layout/xul/grid/reftests/column-sizing-1-ref.xul
@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <hbox>
+    <vbox style="background:aqua">
+      <label value="Left" />
+    </vbox>
+    <vbox style="background:yellow">
+      <textbox value="Right" />
+    </vbox>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/reftests/column-sizing-1.xul b/layout/xul/grid/reftests/column-sizing-1.xul
new file mode 100644
index 0000000000..2a94569ba4
--- /dev/null
+++ b/layout/xul/grid/reftests/column-sizing-1.xul
@@ -0,0 +1,15 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <grid>
+    <columns>
+      <column style="background:aqua">
+        <label value="Left" />
+      </column>
+      <column style="background:yellow">
+        <textbox value="Right" />
+      </column>
+    </columns>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/not-full-basic-ref.xhtml b/layout/xul/grid/reftests/not-full-basic-ref.xhtml
new file mode 100644
index 0000000000..cd233585a3
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-basic-ref.xhtml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+	<title>XUL Grid Test</title>
+	<style type="text/css">
+	html { background: black; }
+	html, body { margin: 0; padding: 0; height: 100%; }
+	div { position: absolute; }
+	</style>
+</head>
+<body>
+
+<div style="background: rgb(0, 102, 153);
+            top: 0px; height: 200px; left: 0px; width: 200px;" />
+<div style="background: rgb(0, 255, 0);
+            top: 200px; bottom: 0px; left: 0px; width: 100px;" />
+<div style="background: rgb(0, 255, 0);
+            top: 200px; height: 100px; left: 100px; width: 100px;" />
+<div style="background: rgb(0, 0, 153);
+            top: 0px; height: 100px; left: 200px; right: 0px;" />
+<div style="background: rgb(0, 0, 153);
+            top: 100px; height: 100px; left: 200px; width: 100px;" />
+
+</body>
+</html>
diff --git a/layout/xul/grid/reftests/not-full-basic.xul b/layout/xul/grid/reftests/not-full-basic.xul
new file mode 100644
index 0000000000..5c7fa91236
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-basic.xul
@@ -0,0 +1,45 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+  ]]></style>
+  <grid flex="1">
+    <columns>
+      <column style="background: rgb(0, 255, 0)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+      <column>
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+      </column>
+      <column>
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row style="background: rgba(0, 0, 255, 0.6)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+      <row>
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+      </row>
+      <row>
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/not-full-grid-pack-align.xul b/layout/xul/grid/reftests/not-full-grid-pack-align.xul
new file mode 100644
index 0000000000..3fe6a95cba
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-grid-pack-align.xul
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+  ]]></style>
+  <!-- align and pack should be no-ops on grid element (not on columns/rows) -->
+  <grid flex="1" align="start" pack="end">
+    <columns>
+      <column style="background: rgb(0, 255, 0)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+      <column>
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+      </column>
+      <column>
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row style="background: rgba(0, 0, 255, 0.6)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+      <row>
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+      </row>
+      <row>
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/not-full-row-group-align-ref.xhtml b/layout/xul/grid/reftests/not-full-row-group-align-ref.xhtml
new file mode 100644
index 0000000000..abef67f87c
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-group-align-ref.xhtml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+	<title>XUL Grid Test</title>
+	<style type="text/css">
+	html { background: black; }
+	html, body { margin: 0; padding: 0; height: 100%; }
+	div { position: absolute; }
+	</style>
+</head>
+<body>
+
+<div style="background: rgb(0, 102, 153);
+            top: 100px; height: 100px; left: 100px; width: 100px;" />
+<div style="background: rgb(0, 255, 0);
+            top: 0px; height: 100px; left: 100px; width: 100px;" />
+<div style="background: rgb(0, 255, 0);
+            top: 200px; height: 100px; left: 100px; width: 100px;" />
+<div style="background: rgb(0, 0, 153);
+            top: 100px; height: 100px; left: 0px; width: 100px;" />
+<div style="background: rgb(0, 0, 153);
+            top: 100px; height: 100px; left: 200px; width: 100px;" />
+
+</body>
+</html>
diff --git a/layout/xul/grid/reftests/not-full-row-group-align.xul b/layout/xul/grid/reftests/not-full-row-group-align.xul
new file mode 100644
index 0000000000..0037d9fb83
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-group-align.xul
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+  ]]></style>
+  <grid flex="1">
+    <!-- does anybody actually *want* the way columns align="start" behaves here? -->
+    <columns align="start">
+      <column style="background: rgb(0, 255, 0)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+      <column>
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+      </column>
+      <column>
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+    </columns>
+    <rows align="start">
+      <row style="background: rgba(0, 0, 255, 0.6)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+      <row>
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+      </row>
+      <row>
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/not-full-row-group-direction-ref.xhtml b/layout/xul/grid/reftests/not-full-row-group-direction-ref.xhtml
new file mode 100644
index 0000000000..b2a92b07b5
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-group-direction-ref.xhtml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+	<title>XUL Grid Test</title>
+	<style type="text/css">
+	html { background: black; }
+	html, body { margin: 0; padding: 0; height: 100%; }
+	div { position: absolute; }
+	</style>
+</head>
+<body>
+
+<div style="background: rgb(0, 102, 153);
+            bottom: 0px; height: 100px; right: 0px; width: 100px;" />
+<div style="background: rgb(0, 0, 153);
+            bottom: 0px; height: 100px; left: 0px; right: 100px;" />
+<div style="background: rgb(0, 0, 153);
+            bottom: 100px; height: 100px; left: 0px; width: 300px;" />
+<div style="background: rgb(0, 255, 0);
+            top: 0px; bottom: 100px; right: 0px; width: 100px;" />
+<div style="background: rgb(0, 255, 0);
+            top: 0px; height: 300px; right: 100px; width: 100px;" />
+
+</body>
+</html>
diff --git a/layout/xul/grid/reftests/not-full-row-group-direction.xul b/layout/xul/grid/reftests/not-full-row-group-direction.xul
new file mode 100644
index 0000000000..c38db40a5e
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-group-direction.xul
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+    rows, columns { -moz-box-direction: reverse; }
+  ]]></style>
+  <grid flex="1">
+    <columns>
+      <column style="background: rgb(0, 255, 0)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+      <column>
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+      </column>
+      <column>
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row style="background: rgba(0, 0, 255, 0.6)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+      <row>
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+      </row>
+      <row>
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/not-full-row-group-pack-ref.xhtml b/layout/xul/grid/reftests/not-full-row-group-pack-ref.xhtml
new file mode 100644
index 0000000000..9232f6ba42
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-group-pack-ref.xhtml
@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+	<title>XUL Grid Test</title>
+	<style type="text/css">
+	html { background: black; }
+	html, body { margin: 0; padding: 0; height: 100%; }
+	div { position: absolute; }
+	</style>
+</head>
+<body>
+
+<div style="background: rgb(0, 102, 153);
+            bottom: 200px; height: 100px; right: 200px; width: 100px;" />
+<div style="background: rgb(0, 0, 153);
+            bottom: 200px; height: 100px; left: 0px; right: 300px;" />
+<div style="background: rgb(0, 0, 153);
+            bottom: 100px; height: 100px; left: 0px; width: 300px;" />
+<div style="background: rgb(0, 0, 153);
+            bottom: 200px; height: 100px; right: 0px; width: 200px;" />
+<div style="background: rgb(0, 255, 0);
+            top: 0px; bottom: 300px; right: 200px; width: 100px;" />
+<div style="background: rgb(0, 255, 0);
+            top: 0px; height: 300px; right: 100px; width: 100px;" />
+<div style="background: rgb(0, 255, 0);
+            bottom: 0px; height: 200px; right: 200px; width: 100px;" />
+
+</body>
+</html>
diff --git a/layout/xul/grid/reftests/not-full-row-group-pack.xul b/layout/xul/grid/reftests/not-full-row-group-pack.xul
new file mode 100644
index 0000000000..bb8f650ae8
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-group-pack.xul
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+    rows, columns { -moz-box-pack: end; }
+  ]]></style>
+  <grid flex="1">
+    <columns>
+      <column style="background: rgb(0, 255, 0)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+      <column>
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+      </column>
+      <column>
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row style="background: rgba(0, 0, 255, 0.6)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+      <row>
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+      </row>
+      <row>
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/not-full-row-leaf-align.xul b/layout/xul/grid/reftests/not-full-row-leaf-align.xul
new file mode 100644
index 0000000000..806514ebde
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-leaf-align.xul
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+    row, column { -moz-box-align: start; }
+  ]]></style>
+  <grid flex="1">
+    <columns>
+      <column style="background: rgb(0, 255, 0)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+      <column>
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+      </column>
+      <column>
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row style="background: rgba(0, 0, 255, 0.6)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+      <row>
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+      </row>
+      <row>
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/not-full-row-leaf-direction.xul b/layout/xul/grid/reftests/not-full-row-leaf-direction.xul
new file mode 100644
index 0000000000..17c3a6585e
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-leaf-direction.xul
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+    row, column { -moz-box-direction: reverse; }
+  ]]></style>
+  <grid flex="1">
+    <columns>
+      <column style="background: rgb(0, 255, 0)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+      <column>
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+      </column>
+      <column>
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row style="background: rgba(0, 0, 255, 0.6)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+      <row>
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+      </row>
+      <row>
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/not-full-row-leaf-pack-ref.xhtml b/layout/xul/grid/reftests/not-full-row-leaf-pack-ref.xhtml
new file mode 100644
index 0000000000..30635313aa
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-leaf-pack-ref.xhtml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+	<title>XUL Grid Test</title>
+	<style type="text/css">
+	html { background: black; }
+	html, body { margin: 0; padding: 0; height: 100%; }
+	div { position: absolute; }
+	</style>
+</head>
+<body>
+
+<div style="background: rgb(0, 102, 153);
+            top: 0px; height: 100px; left: 0px; width: 100px;" />
+<div style="background: rgb(0, 255, 0);
+            top: 100px; bottom: 0px; left: 0px; width: 100px;" />
+<div style="background: rgb(0, 255, 0);
+            bottom: 0px; height: 300px; left: 100px; width: 100px;" />
+<div style="background: rgb(0, 0, 153);
+            top: 0px; height: 100px; left: 100px; right: 0px;" />
+<div style="background: rgb(0, 0, 153);
+            top: 100px; height: 100px; right: 0px; width: 300px;" />
+
+</body>
+</html>
diff --git a/layout/xul/grid/reftests/not-full-row-leaf-pack.xul b/layout/xul/grid/reftests/not-full-row-leaf-pack.xul
new file mode 100644
index 0000000000..8f353c764a
--- /dev/null
+++ b/layout/xul/grid/reftests/not-full-row-leaf-pack.xul
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+    row, column { -moz-box-pack: end; }
+  ]]></style>
+  <grid flex="1">
+    <columns>
+      <column style="background: rgb(0, 255, 0)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+      <column>
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+        <hbox style="background: rgb(0, 255, 0)" />
+      </column>
+      <column>
+        <hbox />
+        <hbox />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row style="background: rgba(0, 0, 255, 0.6)">
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+      <row>
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        <hbox style="background: rgba(0, 0, 255, 0.6)" />
+      </row>
+      <row>
+        <hbox />
+        <hbox />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/reftest-stylo.list b/layout/xul/grid/reftests/reftest-stylo.list
new file mode 100644
index 0000000000..eb73955c9a
--- /dev/null
+++ b/layout/xul/grid/reftests/reftest-stylo.list
@@ -0,0 +1,38 @@
+# DO NOT EDIT! This is a auto-generated temporary list for Stylo testing
+skip-if((B2G&&browserIsRemote)||Mulet) == row-sizing-1.xul row-sizing-1.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == column-sizing-1.xul column-sizing-1.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == row-or-column-sizing-1.xul row-or-column-sizing-1.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == row-or-column-sizing-1.xul row-or-column-sizing-1.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == row-or-column-sizing-1.xul row-or-column-sizing-1.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,60000) == z-order-1.xul z-order-1.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,60000) == z-order-2.xul z-order-2.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,60000) == not-full-basic.xul not-full-basic.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,110000) == not-full-grid-pack-align.xul not-full-grid-pack-align.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,30000) == not-full-row-group-align.xul not-full-row-group-align.xul
+# does anyone want/need this behavior?
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,10000) == not-full-row-group-pack.xul not-full-row-group-pack.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,50000) == not-full-row-group-direction.xul not-full-row-group-direction.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,60000) == not-full-row-leaf-align.xul not-full-row-leaf-align.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,50000) == not-full-row-leaf-pack.xul not-full-row-leaf-pack.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) fuzzy-if(skiaContent,1,80000) == not-full-row-leaf-direction.xul not-full-row-leaf-direction.xul
+skip-if(B2G||Mulet) random-if(transparentScrollbars) fuzzy-if(OSX==1010,1,565) == scrollable-columns.xul scrollable-columns.xul
+# bug 650597
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == scrollable-rows.xul scrollable-rows.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == sizing-2d.xul sizing-2d.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
diff --git a/layout/xul/grid/reftests/reftest.list b/layout/xul/grid/reftests/reftest.list
new file mode 100644
index 0000000000..eb414f9060
--- /dev/null
+++ b/layout/xul/grid/reftests/reftest.list
@@ -0,0 +1,18 @@
+== row-sizing-1.xul row-sizing-1-ref.xul
+== column-sizing-1.xul column-sizing-1-ref.xul
+== row-or-column-sizing-1.xul row-or-column-sizing-2.xul
+== row-or-column-sizing-1.xul row-or-column-sizing-3.xul
+== row-or-column-sizing-1.xul row-or-column-sizing-4.xul
+fuzzy-if(skiaContent,1,60000) == z-order-1.xul z-order-1-ref.xul
+fuzzy-if(skiaContent,1,60000) == z-order-2.xul z-order-2-ref.xul
+fuzzy-if(skiaContent,1,60000) == not-full-basic.xul not-full-basic-ref.xhtml
+fuzzy-if(skiaContent,1,110000) == not-full-grid-pack-align.xul not-full-basic-ref.xhtml
+fuzzy-if(skiaContent,1,30000) == not-full-row-group-align.xul not-full-row-group-align-ref.xhtml # does anyone want/need this behavior?
+fuzzy-if(skiaContent,1,10000) == not-full-row-group-pack.xul not-full-row-group-pack-ref.xhtml
+fuzzy-if(skiaContent,1,50000) == not-full-row-group-direction.xul not-full-row-group-direction-ref.xhtml
+fuzzy-if(skiaContent,1,60000) == not-full-row-leaf-align.xul not-full-basic-ref.xhtml
+fuzzy-if(skiaContent,1,50000) == not-full-row-leaf-pack.xul not-full-row-leaf-pack-ref.xhtml
+fuzzy-if(skiaContent,1,80000) == not-full-row-leaf-direction.xul not-full-row-leaf-pack-ref.xhtml
+random-if(transparentScrollbars) fuzzy-if(OSX==1010,1,565) == scrollable-columns.xul scrollable-columns-ref.xhtml # bug 650597
+fails == scrollable-rows.xul scrollable-rows-ref.xhtml
+== sizing-2d.xul sizing-2d-ref.xul
diff --git a/layout/xul/grid/reftests/row-or-column-sizing-1.xul b/layout/xul/grid/reftests/row-or-column-sizing-1.xul
new file mode 100644
index 0000000000..6c64eef180
--- /dev/null
+++ b/layout/xul/grid/reftests/row-or-column-sizing-1.xul
@@ -0,0 +1,21 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <grid>
+    <columns>
+      <column />
+      <column />
+    </columns>
+    <rows>
+      <row>
+        <hbox />
+        <label value="Upper right" />
+      </row>
+      <row>
+        <textbox value="Lower left" />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/row-or-column-sizing-2.xul b/layout/xul/grid/reftests/row-or-column-sizing-2.xul
new file mode 100644
index 0000000000..008f82fd51
--- /dev/null
+++ b/layout/xul/grid/reftests/row-or-column-sizing-2.xul
@@ -0,0 +1,21 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <grid>
+    <columns>
+      <column>
+        <hbox />
+        <textbox value="Lower left" />
+      </column>
+      <column>
+        <label value="Upper right" />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row />
+      <row />
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/row-or-column-sizing-3.xul b/layout/xul/grid/reftests/row-or-column-sizing-3.xul
new file mode 100644
index 0000000000..1e8e55c294
--- /dev/null
+++ b/layout/xul/grid/reftests/row-or-column-sizing-3.xul
@@ -0,0 +1,27 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <grid>
+    <columns>
+      <column>
+        <hbox />
+        <hbox />
+      </column>
+      <column>
+        <label value="Upper right" />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row>
+        <hbox />
+        <hbox />
+      </row>
+      <row>
+        <textbox value="Lower left" />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/row-or-column-sizing-4.xul b/layout/xul/grid/reftests/row-or-column-sizing-4.xul
new file mode 100644
index 0000000000..5a826fd84c
--- /dev/null
+++ b/layout/xul/grid/reftests/row-or-column-sizing-4.xul
@@ -0,0 +1,27 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <grid>
+    <columns>
+      <column>
+        <hbox />
+        <textbox value="Lower left" />
+      </column>
+      <column>
+        <hbox />
+        <hbox />
+      </column>
+    </columns>
+    <rows>
+      <row>
+        <hbox />
+        <label value="Upper right" />
+      </row>
+      <row>
+        <hbox />
+        <hbox />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/row-sizing-1-ref.xul b/layout/xul/grid/reftests/row-sizing-1-ref.xul
new file mode 100644
index 0000000000..b357190524
--- /dev/null
+++ b/layout/xul/grid/reftests/row-sizing-1-ref.xul
@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        orient="horizontal"
+        title="XUL Grid Test">
+  <vbox>
+    <hbox style="background:aqua">
+      <label value="Top" />
+    </hbox>
+    <hbox style="background:yellow">
+      <textbox value="Bottom" />
+    </hbox>
+  </vbox>
+</window>
diff --git a/layout/xul/grid/reftests/row-sizing-1.xul b/layout/xul/grid/reftests/row-sizing-1.xul
new file mode 100644
index 0000000000..0455b8da44
--- /dev/null
+++ b/layout/xul/grid/reftests/row-sizing-1.xul
@@ -0,0 +1,16 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        orient="horizontal"
+        title="XUL Grid Test">
+  <grid>
+    <rows>
+      <row style="background:aqua">
+        <label value="Top" />
+      </row>
+      <row style="background:yellow">
+        <textbox value="Bottom" />
+      </row>
+    </rows>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/scrollable-columns-ref.xhtml b/layout/xul/grid/reftests/scrollable-columns-ref.xhtml
new file mode 100644
index 0000000000..698c5a036f
--- /dev/null
+++ b/layout/xul/grid/reftests/scrollable-columns-ref.xhtml
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+	<title>XUL Grid Test</title>
+	<style type="text/css">
+	html { background: black; }
+	html, body { margin: 0; padding: 0; height: 100%; }
+	div { position: absolute; }
+	</style>
+</head>
+<body>
+
+<div style="background: rgb(0, 102, 153);
+            top: 0px; height: 200px; left: 0px; width: 200px;" />
+<div style="background: rgb(0, 255, 0); overflow: auto;
+            top: 200px; height: 100px; left: 0px; width: 200px;">
+  <div style="width: 300px; height: 50px" />
+</div>
+<div style="background: rgb(0, 0, 153);
+            top: 100px; height: 100px; left: 200px; width: 100px;" />
+
+</body>
+</html>
diff --git a/layout/xul/grid/reftests/scrollable-columns.xul b/layout/xul/grid/reftests/scrollable-columns.xul
new file mode 100644
index 0000000000..661c4412f4
--- /dev/null
+++ b/layout/xul/grid/reftests/scrollable-columns.xul
@@ -0,0 +1,49 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+    grid { width: 200px; height: 200px; }
+    columns { overflow: auto; }
+  ]]></style>
+  <hbox>
+    <grid>
+      <columns>
+        <column style="background: rgb(0, 255, 0)">
+          <hbox />
+          <hbox />
+          <hbox />
+        </column>
+        <column>
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+        </column>
+        <column>
+          <hbox />
+          <hbox />
+          <hbox />
+        </column>
+      </columns>
+      <rows>
+        <row style="background: rgba(0, 0, 255, 0.6)">
+          <hbox />
+          <hbox />
+          <hbox />
+        </row>
+        <row>
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        </row>
+        <row>
+          <hbox />
+          <hbox />
+          <hbox />
+        </row>
+      </rows>
+    </grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/reftests/scrollable-rows-ref.xhtml b/layout/xul/grid/reftests/scrollable-rows-ref.xhtml
new file mode 100644
index 0000000000..6b5b95f02c
--- /dev/null
+++ b/layout/xul/grid/reftests/scrollable-rows-ref.xhtml
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+	<title>XUL Grid Test</title>
+	<style type="text/css">
+	html { background: black; }
+	html, body { margin: 0; padding: 0; height: 100%; }
+	div { position: absolute; }
+	</style>
+</head>
+<body>
+
+<div style="background: rgb(0, 102, 153);
+            top: 0px; height: 200px; left: 0px; width: 200px;" />
+<div style="background: rgb(0, 0, 153); overflow: auto;
+            top: 0px; height: 200px; left: 200px; width: 100px;">
+  <div style="width: 50px; height: 300px" />
+</div>
+<div style="background: rgb(0, 255, 0);
+            top: 200px; height: 100px; left: 100px; width: 100px;" />
+
+</body>
+</html>
diff --git a/layout/xul/grid/reftests/scrollable-rows.xul b/layout/xul/grid/reftests/scrollable-rows.xul
new file mode 100644
index 0000000000..9fa1f82c52
--- /dev/null
+++ b/layout/xul/grid/reftests/scrollable-rows.xul
@@ -0,0 +1,49 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+    grid { width: 200px; height: 200px; }
+    rows { overflow: auto; }
+  ]]></style>
+  <hbox>
+    <grid>
+      <columns>
+        <column style="background: rgb(0, 255, 0)">
+          <hbox />
+          <hbox />
+          <hbox />
+        </column>
+        <column>
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+        </column>
+        <column>
+          <hbox />
+          <hbox />
+          <hbox />
+        </column>
+      </columns>
+      <rows>
+        <row style="background: rgba(0, 0, 255, 0.6)">
+          <hbox />
+          <hbox />
+          <hbox />
+        </row>
+        <row>
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        </row>
+        <row>
+          <hbox />
+          <hbox />
+          <hbox />
+        </row>
+      </rows>
+    </grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/reftests/sizing-2d-ref.xul b/layout/xul/grid/reftests/sizing-2d-ref.xul
new file mode 100644
index 0000000000..a3bc4ca735
--- /dev/null
+++ b/layout/xul/grid/reftests/sizing-2d-ref.xul
@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" align="start">
+  <hbox>
+    <box style="background:aqua; width: 50px; height: 100px" />
+    <box style="background:fuchsia; width: 100px; height: 100px" />
+  </hbox>
+  <hbox>
+    <box style="background:yellow; width: 50px; height: 75px" />
+    <box style="background:blue; width: 100px; height: 75px" />
+  </hbox>
+</window>
diff --git a/layout/xul/grid/reftests/sizing-2d.xul b/layout/xul/grid/reftests/sizing-2d.xul
new file mode 100644
index 0000000000..7868f9ecaa
--- /dev/null
+++ b/layout/xul/grid/reftests/sizing-2d.xul
@@ -0,0 +1,26 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" align="start">
+  <grid>
+    <rows>
+      <row>
+        <box style="width: 25px; height: 25px" />
+        <box />
+      </row>
+      <row>
+        <box />
+        <box style="width: 75px; height: 75px" />
+      </row>
+    </rows>
+    <columns>
+      <column>
+        <box style="background: aqua" />
+        <box style="background: yellow; width: 50px; height: 50px" />
+      </column>
+      <column>
+        <box style="background: fuchsia; width: 100px; height: 100px" />
+        <box style="background: blue" />
+      </column>
+    </columns>
+  </grid>
+</window>
diff --git a/layout/xul/grid/reftests/z-order-1-ref.xul b/layout/xul/grid/reftests/z-order-1-ref.xul
new file mode 100644
index 0000000000..198c4e6c63
--- /dev/null
+++ b/layout/xul/grid/reftests/z-order-1-ref.xul
@@ -0,0 +1,30 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+  ]]></style>
+  <hbox>
+    <grid>
+      <rows>
+        <row>
+          <hbox style="background: rgb(0, 102, 153)" />
+          <hbox style="background: rgb(0, 102, 153)" />
+          <hbox style="background: rgb(0, 0, 153)" />
+        </row>
+        <row>
+          <hbox style="background: rgb(0, 102, 153)" />
+          <hbox style="background: rgb(0, 102, 153)" />
+          <hbox style="background: rgb(0, 0, 153)" />
+        </row>
+        <row>
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 0, 0)" />
+        </row>
+      </rows>
+    </grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/reftests/z-order-1.xul b/layout/xul/grid/reftests/z-order-1.xul
new file mode 100644
index 0000000000..d38ef9f4a0
--- /dev/null
+++ b/layout/xul/grid/reftests/z-order-1.xul
@@ -0,0 +1,47 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+  ]]></style>
+  <hbox>
+    <grid>
+      <columns>
+        <column style="background: rgb(0, 255, 0)">
+          <hbox />
+          <hbox />
+          <hbox />
+        </column>
+        <column>
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+        </column>
+        <column>
+          <hbox />
+          <hbox />
+          <hbox />
+        </column>
+      </columns>
+      <rows>
+        <row style="background: rgba(0, 0, 255, 0.6)">
+          <hbox />
+          <hbox />
+          <hbox />
+        </row>
+        <row>
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        </row>
+        <row>
+          <hbox />
+          <hbox />
+          <hbox />
+        </row>
+      </rows>
+    </grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/reftests/z-order-2-ref.xul b/layout/xul/grid/reftests/z-order-2-ref.xul
new file mode 100644
index 0000000000..5b0793d6d9
--- /dev/null
+++ b/layout/xul/grid/reftests/z-order-2-ref.xul
@@ -0,0 +1,30 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+  ]]></style>
+  <hbox>
+    <grid>
+      <rows>
+        <row>
+          <hbox style="background: rgb(0, 102, 153)" />
+          <hbox style="background: rgb(0, 102, 153)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+        </row>
+        <row>
+          <hbox style="background: rgb(0, 102, 153)" />
+          <hbox style="background: rgb(0, 102, 153)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+        </row>
+        <row>
+          <hbox style="background: rgb(0, 0, 153)" />
+          <hbox style="background: rgb(0, 0, 153)" />
+          <hbox style="background: rgb(0, 0, 0)" />
+        </row>
+      </rows>
+    </grid>
+  </hbox>
+</window>
diff --git a/layout/xul/grid/reftests/z-order-2.xul b/layout/xul/grid/reftests/z-order-2.xul
new file mode 100644
index 0000000000..b2c270d6b7
--- /dev/null
+++ b/layout/xul/grid/reftests/z-order-2.xul
@@ -0,0 +1,47 @@
+<?xml version="1.0"?>
+<!DOCTYPE window>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        title="XUL Grid Test">
+  <style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
+    window { background: black; }
+    hbox { height: 100px; width: 100px; }
+  ]]></style>
+  <hbox>
+    <grid>
+      <rows>
+        <row style="background: rgb(0, 255, 0)">
+          <hbox />
+          <hbox />
+          <hbox />
+        </row>
+        <row>
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+          <hbox style="background: rgb(0, 255, 0)" />
+        </row>
+        <row>
+          <hbox />
+          <hbox />
+          <hbox />
+        </row>
+      </rows>
+      <columns>
+        <column style="background: rgba(0, 0, 255, 0.6)">
+          <hbox />
+          <hbox />
+          <hbox />
+        </column>
+        <column>
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+          <hbox style="background: rgba(0, 0, 255, 0.6)" />
+        </column>
+        <column>
+          <hbox />
+          <hbox />
+          <hbox />
+        </column>
+      </columns>
+    </grid>
+  </hbox>
+</window>
diff --git a/layout/xul/moz.build b/layout/xul/moz.build
new file mode 100644
index 0000000000..8ed304c9ff
--- /dev/null
+++ b/layout/xul/moz.build
@@ -0,0 +1,107 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+with Files('**'):
+    BUG_COMPONENT = ('Core', 'XP Toolkit/Widgets: XUL')
+
+with Files('*Menu*'):
+    BUG_COMPONENT = ('Core', 'XP Toolkit/Widgets: Menus')
+
+if CONFIG['ENABLE_TESTS']:
+    MOCHITEST_MANIFESTS += ['test/mochitest.ini']
+    MOCHITEST_CHROME_MANIFESTS += ['test/chrome.ini']
+    BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
+
+XPIDL_SOURCES += [
+    'nsIBoxObject.idl',
+    'nsIBrowserBoxObject.idl',
+    'nsIContainerBoxObject.idl',
+    'nsIListBoxObject.idl',
+    'nsIMenuBoxObject.idl',
+    'nsIScrollBoxObject.idl',
+    'nsISliderListener.idl',
+]
+
+XPIDL_MODULE = 'layout_xul'
+
+EXPORTS += [
+    'nsBox.h',
+    'nsIScrollbarMediator.h',
+    'nsPIBoxObject.h',
+    'nsPIListBoxObject.h',
+    'nsXULPopupManager.h',
+]
+
+EXPORTS.mozilla.dom += [
+    'BoxObject.h',
+    'ContainerBoxObject.h',
+    'ListBoxObject.h',
+    'MenuBoxObject.h',
+    'PopupBoxObject.h',
+    'ScrollBoxObject.h',
+]
+
+UNIFIED_SOURCES += [
+    'BoxObject.cpp',
+    'nsBox.cpp',
+    'nsBoxFrame.cpp',
+    'nsBoxLayout.cpp',
+    'nsBoxLayoutState.cpp',
+    'nsButtonBoxFrame.cpp',
+    'nsRepeatService.cpp',
+    'nsRootBoxFrame.cpp',
+    'nsScrollbarButtonFrame.cpp',
+    'nsScrollbarFrame.cpp',
+    'nsScrollBoxFrame.cpp',
+    'nsSliderFrame.cpp',
+    'nsSprocketLayout.cpp',
+    'nsStackFrame.cpp',
+    'nsStackLayout.cpp',
+    'nsXULTooltipListener.cpp',
+]
+
+if CONFIG['MOZ_XUL']:
+    UNIFIED_SOURCES += [
+        'ContainerBoxObject.cpp',
+        'ListBoxObject.cpp',
+        'MenuBoxObject.cpp',
+        'nsDeckFrame.cpp',
+        'nsDocElementBoxFrame.cpp',
+        'nsGroupBoxFrame.cpp',
+        'nsImageBoxFrame.cpp',
+        'nsLeafBoxFrame.cpp',
+        'nsListBoxBodyFrame.cpp',
+        'nsListBoxLayout.cpp',
+        'nsListItemFrame.cpp',
+        'nsMenuBarFrame.cpp',
+        'nsMenuBarListener.cpp',
+        'nsMenuFrame.cpp',
+        'nsMenuPopupFrame.cpp',
+        'nsPopupSetFrame.cpp',
+        'nsProgressMeterFrame.cpp',
+        'nsResizerFrame.cpp',
+        'nsSplitterFrame.cpp',
+        'nsTextBoxFrame.cpp',
+        'nsTitleBarFrame.cpp',
+        'nsXULLabelFrame.cpp',
+        'nsXULPopupManager.cpp',
+        'PopupBoxObject.cpp',
+        'ScrollBoxObject.cpp',
+    ]
+
+if CONFIG['MOZ_XUL']:
+    DIRS += ['tree', 'grid']
+
+FINAL_LIBRARY = 'xul'
+LOCAL_INCLUDES += [
+    '../base',
+    '../generic',
+    '../style',
+    '/dom/base',
+]
+
+if CONFIG['GNU_CXX']:
+    CXXFLAGS += ['-Wno-error=shadow']
diff --git a/layout/xul/nsBox.cpp b/layout/xul/nsBox.cpp
new file mode 100644
index 0000000000..f7ec5fead4
--- /dev/null
+++ b/layout/xul/nsBox.cpp
@@ -0,0 +1,981 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsBoxLayoutState.h"
+#include "nsBox.h"
+#include "nsBoxFrame.h"
+#include "nsPresContext.h"
+#include "nsCOMPtr.h"
+#include "nsIContent.h"
+#include "nsContainerFrame.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsIDOMNode.h"
+#include "nsIDOMMozNamedAttrMap.h"
+#include "nsIDOMAttr.h"
+#include "nsITheme.h"
+#include "nsIServiceManager.h"
+#include "nsBoxLayout.h"
+#include "FrameLayerBuilder.h"
+#include <algorithm>
+
+using namespace mozilla;
+
+#ifdef DEBUG_LAYOUT
+int32_t gIndent = 0;
+#endif
+
+#ifdef DEBUG_LAYOUT
+void
+nsBoxAddIndents()
+{
+    for(int32_t i=0; i < gIndent; i++)
+    {
+        printf(" ");
+    }
+}
+#endif
+
+#ifdef DEBUG_LAYOUT
+void
+nsBox::AppendAttribute(const nsAutoString& aAttribute, const nsAutoString& aValue, nsAutoString& aResult)
+{
+   aResult.Append(aAttribute);
+   aResult.AppendLiteral("='");
+   aResult.Append(aValue);
+   aResult.AppendLiteral("' ");
+}
+
+void
+nsBox::ListBox(nsAutoString& aResult)
+{
+    nsAutoString name;
+    GetBoxName(name);
+
+    char addr[100];
+    sprintf(addr, "[@%p] ", static_cast<void*>(this));
+
+    aResult.AppendASCII(addr);
+    aResult.Append(name);
+    aResult.Append(' ');
+
+    nsIContent* content = GetContent();
+
+    // add on all the set attributes
+    if (content) {
+      nsCOMPtr<nsIDOMNode> node(do_QueryInterface(content));
+      nsCOMPtr<nsIDOMMozNamedAttrMap> namedMap;
+
+      node->GetAttributes(getter_AddRefs(namedMap));
+      uint32_t length;
+      namedMap->GetLength(&length);
+
+      nsCOMPtr<nsIDOMAttr> attribute;
+      for (uint32_t i = 0; i < length; ++i)
+      {
+        namedMap->Item(i, getter_AddRefs(attribute));
+        attribute->GetName(name);
+        nsAutoString value;
+        attribute->GetValue(value);
+        AppendAttribute(name, value, aResult);
+      }
+    }
+}
+
+nsresult
+nsBox::XULDumpBox(FILE* aFile)
+{
+  nsAutoString s;
+  ListBox(s);
+  fprintf(aFile, "%s", NS_LossyConvertUTF16toASCII(s).get());
+  return NS_OK;
+}
+
+void
+nsBox::PropagateDebug(nsBoxLayoutState& aState)
+{
+  // propagate debug information
+  if (mState & NS_STATE_DEBUG_WAS_SET) {
+    if (mState & NS_STATE_SET_TO_DEBUG)
+      SetXULDebug(aState, true);
+    else
+      SetXULDebug(aState, false);
+  } else if (mState & NS_STATE_IS_ROOT) {
+    SetXULDebug(aState, gDebug);
+  }
+}
+#endif
+
+#ifdef DEBUG_LAYOUT
+void
+nsBox::GetBoxName(nsAutoString& aName)
+{
+  aName.AssignLiteral("Box");
+}
+#endif
+
+nsresult
+nsBox::BeginXULLayout(nsBoxLayoutState& aState)
+{
+#ifdef DEBUG_LAYOUT 
+
+  nsBoxAddIndents();
+  printf("XULLayout: ");
+  XULDumpBox(stdout);
+  printf("\n");
+  gIndent++;
+#endif
+
+  // mark ourselves as dirty so no child under us
+  // can post an incremental layout.
+  // XXXldb Is this still needed?
+  mState |= NS_FRAME_HAS_DIRTY_CHILDREN;
+
+  if (GetStateBits() & NS_FRAME_IS_DIRTY)
+  {
+    // If the parent is dirty, all the children are dirty (ReflowInput
+    // does this too).
+    nsIFrame* box;
+    for (box = GetChildXULBox(this); box; box = GetNextXULBox(box))
+      box->AddStateBits(NS_FRAME_IS_DIRTY);
+  }
+
+  // Another copy-over from ReflowInput.
+  // Since we are in reflow, we don't need to store these properties anymore.
+  FrameProperties props = Properties();
+  props.Delete(UsedBorderProperty());
+  props.Delete(UsedPaddingProperty());
+  props.Delete(UsedMarginProperty());
+
+#ifdef DEBUG_LAYOUT
+  PropagateDebug(aState);
+#endif
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBox::DoXULLayout(nsBoxLayoutState& aState)
+{
+  return NS_OK;
+}
+
+nsresult
+nsBox::EndXULLayout(nsBoxLayoutState& aState)
+{
+
+  #ifdef DEBUG_LAYOUT
+      --gIndent;
+  #endif
+
+  return SyncLayout(aState);
+}
+
+bool nsBox::gGotTheme = false;
+nsITheme* nsBox::gTheme = nullptr;
+
+nsBox::nsBox()
+{
+  MOZ_COUNT_CTOR(nsBox);
+  //mX = 0;
+  //mY = 0;
+  if (!gGotTheme) {
+    gGotTheme = true;
+    CallGetService("@mozilla.org/chrome/chrome-native-theme;1", &gTheme);
+  }
+}
+
+nsBox::~nsBox()
+{
+  // NOTE:  This currently doesn't get called for |nsBoxToBlockAdaptor|
+  // objects, so don't rely on putting anything here.
+  MOZ_COUNT_DTOR(nsBox);
+}
+
+/* static */ void
+nsBox::Shutdown()
+{
+  gGotTheme = false;
+  NS_IF_RELEASE(gTheme);
+}
+
+nsresult
+nsBox::XULRelayoutChildAtOrdinal(nsIFrame* aChild)
+{
+  return NS_OK;
+}
+
+nsresult
+nsIFrame::GetXULClientRect(nsRect& aClientRect)
+{
+  aClientRect = mRect;
+  aClientRect.MoveTo(0,0);
+
+  nsMargin borderPadding;
+  GetXULBorderAndPadding(borderPadding);
+
+  aClientRect.Deflate(borderPadding);
+
+  if (aClientRect.width < 0)
+     aClientRect.width = 0;
+
+  if (aClientRect.height < 0)
+     aClientRect.height = 0;
+
+ // NS_ASSERTION(aClientRect.width >=0 && aClientRect.height >= 0, "Content Size < 0");
+
+  return NS_OK;
+}
+
+void
+nsBox::SetXULBounds(nsBoxLayoutState& aState, const nsRect& aRect, bool aRemoveOverflowAreas)
+{
+    NS_BOX_ASSERTION(this, aRect.width >=0 && aRect.height >= 0, "SetXULBounds Size < 0");
+
+    nsRect rect(mRect);
+
+    uint32_t flags = GetXULLayoutFlags();
+
+    uint32_t stateFlags = aState.LayoutFlags();
+
+    flags |= stateFlags;
+
+    if ((flags & NS_FRAME_NO_MOVE_FRAME) == NS_FRAME_NO_MOVE_FRAME)
+      SetSize(aRect.Size());
+    else
+      SetRect(aRect);
+
+    // Nuke the overflow area. The caller is responsible for restoring
+    // it if necessary.
+    if (aRemoveOverflowAreas) {
+      // remove the previously stored overflow area
+      ClearOverflowRects();
+    }
+
+    if (!(flags & NS_FRAME_NO_MOVE_VIEW))
+    {
+      nsContainerFrame::PositionFrameView(this);
+      if ((rect.x != aRect.x) || (rect.y != aRect.y))
+        nsContainerFrame::PositionChildViews(this);
+    }
+  
+
+   /*  
+    // only if the origin changed
+    if ((rect.x != aRect.x) || (rect.y != aRect.y))  {
+      if (frame->HasView()) {
+        nsContainerFrame::PositionFrameView(presContext, frame,
+                                            frame->GetView());
+      } else {
+        nsContainerFrame::PositionChildViews(presContext, frame);
+      }
+    }
+    */
+}
+
+nsresult
+nsIFrame::GetXULBorderAndPadding(nsMargin& aBorderAndPadding)
+{
+  aBorderAndPadding.SizeTo(0, 0, 0, 0);
+  nsresult rv = GetXULBorder(aBorderAndPadding);
+  if (NS_FAILED(rv))
+    return rv;
+
+  nsMargin padding;
+  rv = GetXULPadding(padding);
+  if (NS_FAILED(rv))
+    return rv;
+
+  aBorderAndPadding += padding;
+
+  return rv;
+}
+
+nsresult
+nsBox::GetXULBorder(nsMargin& aMargin)
+{
+  aMargin.SizeTo(0,0,0,0);
+    
+  const nsStyleDisplay* disp = StyleDisplay();
+  if (disp->mAppearance && gTheme) {
+    // Go to the theme for the border.
+    nsPresContext *context = PresContext();
+    if (gTheme->ThemeSupportsWidget(context, this, disp->mAppearance)) {
+      nsIntMargin margin(0, 0, 0, 0);
+      gTheme->GetWidgetBorder(context->DeviceContext(), this,
+                              disp->mAppearance, &margin);
+      aMargin.top = context->DevPixelsToAppUnits(margin.top);
+      aMargin.right = context->DevPixelsToAppUnits(margin.right);
+      aMargin.bottom = context->DevPixelsToAppUnits(margin.bottom);
+      aMargin.left = context->DevPixelsToAppUnits(margin.left);
+      return NS_OK;
+    }
+  }
+
+  aMargin = StyleBorder()->GetComputedBorder();
+
+  return NS_OK;
+}
+
+nsresult
+nsBox::GetXULPadding(nsMargin& aMargin)
+{
+  const nsStyleDisplay *disp = StyleDisplay();
+  if (disp->mAppearance && gTheme) {
+    // Go to the theme for the padding.
+    nsPresContext *context = PresContext();
+    if (gTheme->ThemeSupportsWidget(context, this, disp->mAppearance)) {
+      nsIntMargin margin(0, 0, 0, 0);
+      bool useThemePadding;
+
+      useThemePadding = gTheme->GetWidgetPadding(context->DeviceContext(),
+                                                 this, disp->mAppearance,
+                                                 &margin);
+      if (useThemePadding) {
+        aMargin.top = context->DevPixelsToAppUnits(margin.top);
+        aMargin.right = context->DevPixelsToAppUnits(margin.right);
+        aMargin.bottom = context->DevPixelsToAppUnits(margin.bottom);
+        aMargin.left = context->DevPixelsToAppUnits(margin.left);
+        return NS_OK;
+      }
+    }
+  }
+
+  aMargin.SizeTo(0,0,0,0);
+  StylePadding()->GetPadding(aMargin);
+
+  return NS_OK;
+}
+
+nsresult
+nsBox::GetXULMargin(nsMargin& aMargin)
+{
+  aMargin.SizeTo(0,0,0,0);
+  StyleMargin()->GetMargin(aMargin);
+
+  return NS_OK;
+}
+
+void
+nsBox::SizeNeedsRecalc(nsSize& aSize)
+{
+  aSize.width  = -1;
+  aSize.height = -1;
+}
+
+void
+nsBox::CoordNeedsRecalc(nscoord& aFlex)
+{
+  aFlex = -1;
+}
+
+bool
+nsBox::DoesNeedRecalc(const nsSize& aSize)
+{
+  return (aSize.width == -1 || aSize.height == -1);
+}
+
+bool
+nsBox::DoesNeedRecalc(nscoord aCoord)
+{
+  return (aCoord == -1);
+}
+
+nsSize
+nsBox::GetXULPrefSize(nsBoxLayoutState& aState)
+{
+  NS_ASSERTION(aState.GetRenderingContext(), "must have rendering context");
+
+  nsSize pref(0,0);
+  DISPLAY_PREF_SIZE(this, pref);
+
+  if (IsXULCollapsed())
+    return pref;
+
+  AddBorderAndPadding(pref);
+  bool widthSet, heightSet;
+  nsIFrame::AddXULPrefSize(this, pref, widthSet, heightSet);
+
+  nsSize minSize = GetXULMinSize(aState);
+  nsSize maxSize = GetXULMaxSize(aState);
+  return BoundsCheck(minSize, pref, maxSize);
+}
+
+nsSize
+nsBox::GetXULMinSize(nsBoxLayoutState& aState)
+{
+  NS_ASSERTION(aState.GetRenderingContext(), "must have rendering context");
+
+  nsSize min(0,0);
+  DISPLAY_MIN_SIZE(this, min);
+
+  if (IsXULCollapsed())
+    return min;
+
+  AddBorderAndPadding(min);
+  bool widthSet, heightSet;
+  nsIFrame::AddXULMinSize(aState, this, min, widthSet, heightSet);
+  return min;
+}
+
+nsSize
+nsBox::GetXULMinSizeForScrollArea(nsBoxLayoutState& aBoxLayoutState)
+{
+  return nsSize(0, 0);
+}
+
+nsSize
+nsBox::GetXULMaxSize(nsBoxLayoutState& aState)
+{
+  NS_ASSERTION(aState.GetRenderingContext(), "must have rendering context");
+
+  nsSize maxSize(NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+  DISPLAY_MAX_SIZE(this, maxSize);
+
+  if (IsXULCollapsed())
+    return maxSize;
+
+  AddBorderAndPadding(maxSize);
+  bool widthSet, heightSet;
+  nsIFrame::AddXULMaxSize(this, maxSize, widthSet, heightSet);
+  return maxSize;
+}
+
+nscoord
+nsBox::GetXULFlex()
+{
+  nscoord flex = 0;
+
+  nsIFrame::AddXULFlex(this, flex);
+
+  return flex;
+}
+
+uint32_t
+nsIFrame::GetXULOrdinal()
+{
+  uint32_t ordinal = StyleXUL()->mBoxOrdinal;
+
+  // When present, attribute value overrides CSS.
+  nsIContent* content = GetContent();
+  if (content && content->IsXULElement()) {
+    nsresult error;
+    nsAutoString value;
+
+    content->GetAttr(kNameSpaceID_None, nsGkAtoms::ordinal, value);
+    if (!value.IsEmpty()) {
+      ordinal = value.ToInteger(&error);
+    }
+  }
+
+  return ordinal;
+}
+
+nscoord
+nsBox::GetXULBoxAscent(nsBoxLayoutState& aState)
+{
+  if (IsXULCollapsed())
+    return 0;
+
+  return GetXULPrefSize(aState).height;
+}
+
+bool
+nsBox::IsXULCollapsed()
+{
+  return StyleVisibility()->mVisible == NS_STYLE_VISIBILITY_COLLAPSE;
+}
+
+nsresult
+nsIFrame::XULLayout(nsBoxLayoutState& aState)
+{
+  NS_ASSERTION(aState.GetRenderingContext(), "must have rendering context");
+
+  nsBox *box = static_cast<nsBox*>(this);
+  DISPLAY_LAYOUT(box);
+
+  box->BeginXULLayout(aState);
+
+  box->DoXULLayout(aState);
+
+  box->EndXULLayout(aState);
+
+  return NS_OK;
+}
+
+bool
+nsBox::DoesClipChildren()
+{
+  const nsStyleDisplay* display = StyleDisplay();
+  NS_ASSERTION((display->mOverflowY == NS_STYLE_OVERFLOW_CLIP) ==
+               (display->mOverflowX == NS_STYLE_OVERFLOW_CLIP),
+               "If one overflow is clip, the other should be too");
+  return display->mOverflowX == NS_STYLE_OVERFLOW_CLIP;
+}
+
+nsresult
+nsBox::SyncLayout(nsBoxLayoutState& aState)
+{
+  /*
+  if (IsXULCollapsed()) {
+    CollapseChild(aState, this, true);
+    return NS_OK;
+  }
+  */
+  
+
+  if (GetStateBits() & NS_FRAME_IS_DIRTY)
+     XULRedraw(aState);
+
+  RemoveStateBits(NS_FRAME_HAS_DIRTY_CHILDREN | NS_FRAME_IS_DIRTY
+                  | NS_FRAME_FIRST_REFLOW | NS_FRAME_IN_REFLOW);
+
+  nsPresContext* presContext = aState.PresContext();
+
+  uint32_t flags = GetXULLayoutFlags();
+
+  uint32_t stateFlags = aState.LayoutFlags();
+
+  flags |= stateFlags;
+
+  nsRect visualOverflow;
+
+  if (ComputesOwnOverflowArea()) {
+    visualOverflow = GetVisualOverflowRect();
+  }
+  else {
+    nsRect rect(nsPoint(0, 0), GetSize());
+    nsOverflowAreas overflowAreas(rect, rect);
+    if (!DoesClipChildren() && !IsXULCollapsed()) {
+      // See if our child frames caused us to overflow after being laid
+      // out. If so, store the overflow area.  This normally can't happen
+      // in XUL, but it can happen with the CSS 'outline' property and
+      // possibly with other exotic stuff (e.g. relatively positioned
+      // frames in HTML inside XUL).
+      nsLayoutUtils::UnionChildOverflow(this, overflowAreas);
+    }
+
+    FinishAndStoreOverflow(overflowAreas, GetSize());
+    visualOverflow = overflowAreas.VisualOverflow();
+  }
+
+  nsView* view = GetView();
+  if (view) {
+    // Make sure the frame's view is properly sized and positioned and has
+    // things like opacity correct
+    nsContainerFrame::SyncFrameViewAfterReflow(presContext, this, view,
+                                               visualOverflow, flags);
+  } 
+
+  return NS_OK;
+}
+
+nsresult
+nsIFrame::XULRedraw(nsBoxLayoutState& aState)
+{
+  if (aState.PaintingDisabled())
+    return NS_OK;
+
+  // nsStackLayout, at least, expects us to repaint descendants even
+  // if a damage rect is provided
+  InvalidateFrameSubtree();
+
+  return NS_OK;
+}
+
+bool
+nsIFrame::AddXULPrefSize(nsIFrame* aBox, nsSize& aSize, bool &aWidthSet, bool &aHeightSet)
+{
+    aWidthSet = false;
+    aHeightSet = false;
+
+    // add in the css min, max, pref
+    const nsStylePosition* position = aBox->StylePosition();
+
+    // see if the width or height was specifically set
+    // XXX Handle eStyleUnit_Enumerated?
+    // (Handling the eStyleUnit_Enumerated types requires
+    // GetXULPrefSize/GetXULMinSize methods that don't consider
+    // (min-/max-/)(width/height) properties.)
+    const nsStyleCoord &width = position->mWidth;
+    if (width.GetUnit() == eStyleUnit_Coord) {
+        aSize.width = width.GetCoordValue();
+        aWidthSet = true;
+    } else if (width.IsCalcUnit()) {
+        if (!width.CalcHasPercent()) {
+            // pass 0 for percentage basis since we know there are no %s
+            aSize.width = nsRuleNode::ComputeComputedCalc(width, 0);
+            if (aSize.width < 0)
+                aSize.width = 0;
+            aWidthSet = true;
+        }
+    }
+
+    const nsStyleCoord &height = position->mHeight;
+    if (height.GetUnit() == eStyleUnit_Coord) {
+        aSize.height = height.GetCoordValue();
+        aHeightSet = true;
+    } else if (height.IsCalcUnit()) {
+        if (!height.CalcHasPercent()) {
+            // pass 0 for percentage basis since we know there are no %s
+            aSize.height = nsRuleNode::ComputeComputedCalc(height, 0);
+            if (aSize.height < 0)
+                aSize.height = 0;
+            aHeightSet = true;
+        }
+    }
+
+    nsIContent* content = aBox->GetContent();
+    // ignore 'height' and 'width' attributes if the actual element is not XUL
+    // For example, we might be magic XUL frames whose primary content is an HTML
+    // <select>
+    if (content && content->IsXULElement()) {
+        nsAutoString value;
+        nsresult error;
+
+        content->GetAttr(kNameSpaceID_None, nsGkAtoms::width, value);
+        if (!value.IsEmpty()) {
+            value.Trim("%");
+
+            aSize.width =
+              nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+            aWidthSet = true;
+        }
+
+        content->GetAttr(kNameSpaceID_None, nsGkAtoms::height, value);
+        if (!value.IsEmpty()) {
+            value.Trim("%");
+
+            aSize.height =
+              nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+            aHeightSet = true;
+        }
+    }
+
+    return (aWidthSet && aHeightSet);
+}
+
+
+bool
+nsIFrame::AddXULMinSize(nsBoxLayoutState& aState, nsIFrame* aBox, nsSize& aSize,
+                      bool &aWidthSet, bool &aHeightSet)
+{
+    aWidthSet = false;
+    aHeightSet = false;
+
+    bool canOverride = true;
+
+    // See if a native theme wants to supply a minimum size.
+    const nsStyleDisplay* display = aBox->StyleDisplay();
+    if (display->mAppearance) {
+      nsITheme *theme = aState.PresContext()->GetTheme();
+      if (theme && theme->ThemeSupportsWidget(aState.PresContext(), aBox, display->mAppearance)) {
+        LayoutDeviceIntSize size;
+        theme->GetMinimumWidgetSize(aState.PresContext(), aBox,
+                                    display->mAppearance, &size, &canOverride);
+        if (size.width) {
+          aSize.width = aState.PresContext()->DevPixelsToAppUnits(size.width);
+          aWidthSet = true;
+        }
+        if (size.height) {
+          aSize.height = aState.PresContext()->DevPixelsToAppUnits(size.height);
+          aHeightSet = true;
+        }
+      }
+    }
+
+    // add in the css min, max, pref
+    const nsStylePosition* position = aBox->StylePosition();
+
+    // same for min size. Unfortunately min size is always set to 0. So for now
+    // we will assume 0 (as a coord) means not set.
+    const nsStyleCoord &minWidth = position->mMinWidth;
+    if ((minWidth.GetUnit() == eStyleUnit_Coord &&
+         minWidth.GetCoordValue() != 0) ||
+        (minWidth.IsCalcUnit() && !minWidth.CalcHasPercent())) {
+        nscoord min = nsRuleNode::ComputeCoordPercentCalc(minWidth, 0);
+        if (!aWidthSet || (min > aSize.width && canOverride)) {
+           aSize.width = min;
+           aWidthSet = true;
+        }
+    } else if (minWidth.GetUnit() == eStyleUnit_Percent) {
+        NS_ASSERTION(minWidth.GetPercentValue() == 0.0f,
+          "Non-zero percentage values not currently supported");
+        aSize.width = 0;
+        aWidthSet = true; // FIXME: should we really do this for
+                             // nonzero values?
+    }
+    // XXX Handle eStyleUnit_Enumerated?
+    // (Handling the eStyleUnit_Enumerated types requires
+    // GetXULPrefSize/GetXULMinSize methods that don't consider
+    // (min-/max-/)(width/height) properties.
+    // calc() with percentage is treated like '0' (unset)
+
+    const nsStyleCoord &minHeight = position->mMinHeight;
+    if ((minHeight.GetUnit() == eStyleUnit_Coord &&
+         minHeight.GetCoordValue() != 0) ||
+        (minHeight.IsCalcUnit() && !minHeight.CalcHasPercent())) {
+        nscoord min = nsRuleNode::ComputeCoordPercentCalc(minHeight, 0);
+        if (!aHeightSet || (min > aSize.height && canOverride)) {
+           aSize.height = min;
+           aHeightSet = true;
+        }
+    } else if (minHeight.GetUnit() == eStyleUnit_Percent) {
+        NS_ASSERTION(position->mMinHeight.GetPercentValue() == 0.0f,
+          "Non-zero percentage values not currently supported");
+        aSize.height = 0;
+        aHeightSet = true; // FIXME: should we really do this for
+                              // nonzero values?
+    }
+    // calc() with percentage is treated like '0' (unset)
+
+    nsIContent* content = aBox->GetContent();
+    if (content && content->IsXULElement()) {
+        nsAutoString value;
+        nsresult error;
+
+        content->GetAttr(kNameSpaceID_None, nsGkAtoms::minwidth, value);
+        if (!value.IsEmpty())
+        {
+            value.Trim("%");
+
+            nscoord val =
+              nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+            if (val > aSize.width)
+              aSize.width = val;
+            aWidthSet = true;
+        }
+
+        content->GetAttr(kNameSpaceID_None, nsGkAtoms::minheight, value);
+        if (!value.IsEmpty())
+        {
+            value.Trim("%");
+
+            nscoord val =
+              nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+            if (val > aSize.height)
+              aSize.height = val;
+
+            aHeightSet = true;
+        }
+    }
+
+    return (aWidthSet && aHeightSet);
+}
+
+bool
+nsIFrame::AddXULMaxSize(nsIFrame* aBox, nsSize& aSize, bool &aWidthSet, bool &aHeightSet)
+{
+    aWidthSet = false;
+    aHeightSet = false;
+
+    // add in the css min, max, pref
+    const nsStylePosition* position = aBox->StylePosition();
+
+    // and max
+    // see if the width or height was specifically set
+    // XXX Handle eStyleUnit_Enumerated?
+    // (Handling the eStyleUnit_Enumerated types requires
+    // GetXULPrefSize/GetXULMinSize methods that don't consider
+    // (min-/max-/)(width/height) properties.)
+    const nsStyleCoord maxWidth = position->mMaxWidth;
+    if (maxWidth.ConvertsToLength()) {
+        aSize.width = nsRuleNode::ComputeCoordPercentCalc(maxWidth, 0);
+        aWidthSet = true;
+    }
+    // percentages and calc() with percentages are treated like 'none'
+
+    const nsStyleCoord &maxHeight = position->mMaxHeight;
+    if (maxHeight.ConvertsToLength()) {
+        aSize.height = nsRuleNode::ComputeCoordPercentCalc(maxHeight, 0);
+        aHeightSet = true;
+    }
+    // percentages and calc() with percentages are treated like 'none'
+
+    nsIContent* content = aBox->GetContent();
+    if (content && content->IsXULElement()) {
+        nsAutoString value;
+        nsresult error;
+
+        content->GetAttr(kNameSpaceID_None, nsGkAtoms::maxwidth, value);
+        if (!value.IsEmpty()) {
+            value.Trim("%");
+
+            nscoord val =
+              nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+            aSize.width = val;
+            aWidthSet = true;
+        }
+
+        content->GetAttr(kNameSpaceID_None, nsGkAtoms::maxheight, value);
+        if (!value.IsEmpty()) {
+            value.Trim("%");
+
+            nscoord val =
+              nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+            aSize.height = val;
+
+            aHeightSet = true;
+        }
+    }
+
+    return (aWidthSet || aHeightSet);
+}
+
+bool
+nsIFrame::AddXULFlex(nsIFrame* aBox, nscoord& aFlex)
+{
+    bool flexSet = false;
+
+    // get the flexibility
+    aFlex = aBox->StyleXUL()->mBoxFlex;
+
+    // attribute value overrides CSS
+    nsIContent* content = aBox->GetContent();
+    if (content && content->IsXULElement()) {
+        nsresult error;
+        nsAutoString value;
+
+        content->GetAttr(kNameSpaceID_None, nsGkAtoms::flex, value);
+        if (!value.IsEmpty()) {
+            value.Trim("%");
+            aFlex = value.ToInteger(&error);
+            flexSet = true;
+        }
+    }
+
+    if (aFlex < 0)
+      aFlex = 0;
+    if (aFlex >= nscoord_MAX)
+      aFlex = nscoord_MAX - 1;
+
+    return flexSet || aFlex > 0;
+}
+
+void
+nsBox::AddBorderAndPadding(nsSize& aSize)
+{
+  AddBorderAndPadding(this, aSize);
+}
+
+void
+nsBox::AddBorderAndPadding(nsIFrame* aBox, nsSize& aSize)
+{
+  nsMargin borderPadding(0,0,0,0);
+  aBox->GetXULBorderAndPadding(borderPadding);
+  AddMargin(aSize, borderPadding);
+}
+
+void
+nsBox::AddMargin(nsIFrame* aChild, nsSize& aSize)
+{
+  nsMargin margin(0,0,0,0);
+  aChild->GetXULMargin(margin);
+  AddMargin(aSize, margin);
+}
+
+void
+nsBox::AddMargin(nsSize& aSize, const nsMargin& aMargin)
+{
+  if (aSize.width != NS_INTRINSICSIZE)
+    aSize.width += aMargin.left + aMargin.right;
+
+  if (aSize.height != NS_INTRINSICSIZE)
+     aSize.height += aMargin.top + aMargin.bottom;
+}
+
+nscoord
+nsBox::BoundsCheck(nscoord aMin, nscoord aPref, nscoord aMax)
+{
+   if (aPref > aMax)
+       aPref = aMax;
+
+   if (aPref < aMin)
+       aPref = aMin;
+
+   return aPref;
+}
+
+nsSize
+nsBox::BoundsCheckMinMax(const nsSize& aMinSize, const nsSize& aMaxSize)
+{
+  return nsSize(std::max(aMaxSize.width, aMinSize.width),
+                std::max(aMaxSize.height, aMinSize.height));
+}
+
+nsSize
+nsBox::BoundsCheck(const nsSize& aMinSize, const nsSize& aPrefSize, const nsSize& aMaxSize)
+{
+  return nsSize(BoundsCheck(aMinSize.width, aPrefSize.width, aMaxSize.width),
+                BoundsCheck(aMinSize.height, aPrefSize.height, aMaxSize.height));
+}
+
+/*static*/ nsIFrame*
+nsBox::GetChildXULBox(const nsIFrame* aFrame)
+{
+  // box layout ends at box-wrapped frames, so don't allow these frames
+  // to report child boxes.
+  return aFrame->IsXULBoxFrame() ? aFrame->PrincipalChildList().FirstChild() : nullptr;
+}
+
+/*static*/ nsIFrame*
+nsBox::GetNextXULBox(const nsIFrame* aFrame)
+{
+  return aFrame->GetParent() &&
+    aFrame->GetParent()->IsXULBoxFrame() ? aFrame->GetNextSibling() : nullptr;
+}
+
+/*static*/ nsIFrame*
+nsBox::GetParentXULBox(const nsIFrame* aFrame)
+{
+  return aFrame->GetParent() &&
+    aFrame->GetParent()->IsXULBoxFrame() ? aFrame->GetParent() : nullptr;
+}
+
+#ifdef DEBUG_LAYOUT
+nsresult
+nsBox::SetXULDebug(nsBoxLayoutState& aState, bool aDebug)
+{
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBox::GetDebugBoxAt( const nsPoint& aPoint,
+                      nsIFrame**     aBox)
+{
+  nsRect thisRect(nsPoint(0,0), GetSize());
+  if (!thisRect.Contains(aPoint))
+    return NS_ERROR_FAILURE;
+
+  nsIFrame* child = nsBox::GetChildXULBox(this);
+  nsIFrame* hit = nullptr;
+
+  *aBox = nullptr;
+  while (nullptr != child) {
+    nsresult rv = child->GetDebugBoxAt(aPoint - child->GetOffsetTo(this), &hit);
+
+    if (NS_SUCCEEDED(rv) && hit) {
+      *aBox = hit;
+    }
+    child = GetNextXULBox(child);
+  }
+
+  // found a child
+  if (*aBox) {
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+
+nsresult
+nsBox::GetXULDebug(bool& aDebug)
+{
+  aDebug = false;
+  return NS_OK;
+}
+
+#endif
diff --git a/layout/xul/nsBox.h b/layout/xul/nsBox.h
new file mode 100644
index 0000000000..bf019c1744
--- /dev/null
+++ b/layout/xul/nsBox.h
@@ -0,0 +1,127 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsBox_h___
+#define nsBox_h___
+
+#include "mozilla/Attributes.h"
+#include "nsIFrame.h"
+
+class nsITheme;
+
+class nsBox : public nsIFrame {
+
+public:
+
+  friend class nsIFrame;
+
+  static void Shutdown();
+
+  virtual nsSize GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMaxSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nscoord GetXULFlex() override;
+  virtual nscoord GetXULBoxAscent(nsBoxLayoutState& aBoxLayoutState) override;
+
+  virtual nsSize GetXULMinSizeForScrollArea(nsBoxLayoutState& aBoxLayoutState) override;
+
+  virtual bool IsXULCollapsed() override;
+
+  virtual void SetXULBounds(nsBoxLayoutState& aBoxLayoutState, const nsRect& aRect,
+                            bool aRemoveOverflowAreas = false) override;
+
+  virtual nsresult GetXULBorder(nsMargin& aBorderAndPadding) override;
+  virtual nsresult GetXULPadding(nsMargin& aBorderAndPadding) override;
+  virtual nsresult GetXULMargin(nsMargin& aMargin) override;
+
+  virtual Valignment GetXULVAlign() const override { return vAlign_Top; }
+  virtual Halignment GetXULHAlign() const override { return hAlign_Left; }
+
+  virtual nsresult XULRelayoutChildAtOrdinal(nsIFrame* aChild) override;
+
+#ifdef DEBUG_LAYOUT
+  NS_IMETHOD GetDebugBoxAt(const nsPoint& aPoint, nsIFrame** aBox);
+  virtual nsresult GetXULDebug(bool& aDebug) override;
+  virtual nsresult SetXULDebug(nsBoxLayoutState& aState, bool aDebug) override;
+
+  virtual nsresult XULDumpBox(FILE* out) override;
+  void PropagateDebug(nsBoxLayoutState& aState);
+#endif
+
+  nsBox();
+  virtual ~nsBox();
+
+  /**
+   * Returns true if this box clips its children, e.g., if this box is an sc
+rollbox.
+  */
+  virtual bool DoesClipChildren();
+  virtual bool ComputesOwnOverflowArea() = 0;
+
+  nsresult SyncLayout(nsBoxLayoutState& aBoxLayoutState);
+
+  bool DoesNeedRecalc(const nsSize& aSize);
+  bool DoesNeedRecalc(nscoord aCoord);
+  void SizeNeedsRecalc(nsSize& aSize);
+  void CoordNeedsRecalc(nscoord& aCoord);
+
+  void AddBorderAndPadding(nsSize& aSize);
+
+  static void AddBorderAndPadding(nsIFrame* aBox, nsSize& aSize);
+  static void AddMargin(nsIFrame* aChild, nsSize& aSize);
+  static void AddMargin(nsSize& aSize, const nsMargin& aMargin);
+
+  static nsSize BoundsCheckMinMax(const nsSize& aMinSize, const nsSize& aMaxSize);
+  static nsSize BoundsCheck(const nsSize& aMinSize, const nsSize& aPrefSize, const nsSize& aMaxSize);
+  static nscoord BoundsCheck(nscoord aMinSize, nscoord aPrefSize, nscoord aMaxSize);
+
+  static nsIFrame* GetChildXULBox(const nsIFrame* aFrame);
+  static nsIFrame* GetNextXULBox(const nsIFrame* aFrame);
+  static nsIFrame* GetParentXULBox(const nsIFrame* aFrame);
+
+protected:
+
+#ifdef DEBUG_LAYOUT
+  virtual void AppendAttribute(const nsAutoString& aAttribute, const nsAutoString& aValue, nsAutoString& aResult);
+
+  virtual void ListBox(nsAutoString& aResult);
+#endif
+
+  nsresult BeginXULLayout(nsBoxLayoutState& aState);
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aBoxLayoutState);
+  nsresult EndXULLayout(nsBoxLayoutState& aState);
+
+#ifdef DEBUG_LAYOUT
+  virtual void GetBoxName(nsAutoString& aName);
+  void PropagateDebug(nsBoxLayoutState& aState);
+#endif
+
+  static bool gGotTheme;
+  static nsITheme* gTheme;
+
+  enum eMouseThrough {
+    unset,
+    never,
+    always
+  };
+
+private:
+
+  //nscoord mX;
+  //nscoord mY;
+};
+
+#ifdef DEBUG_LAYOUT
+#define NS_BOX_ASSERTION(box,expr,str) \
+  if (!(expr)) { \
+       box->XULDumpBox(stdout); \
+       NS_DebugBreak(NSDebugAssertion, str, #expr, __FILE__, __LINE__); \
+  }
+#else
+#define NS_BOX_ASSERTION(box,expr,str) {}
+#endif
+
+#endif
+
diff --git a/layout/xul/nsBoxFrame.cpp b/layout/xul/nsBoxFrame.cpp
new file mode 100644
index 0000000000..9ca351d945
--- /dev/null
+++ b/layout/xul/nsBoxFrame.cpp
@@ -0,0 +1,2111 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sw=2 et tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+// How boxes layout
+// ----------------
+// Boxes layout a bit differently than html. html does a bottom up layout. Where boxes do a top down.
+// 1) First thing a box does it goes out and askes each child for its min, max, and preferred sizes.
+// 2) It then adds them up to determine its size.
+// 3) If the box was asked to layout it self intrinically it will layout its children at their preferred size
+//    otherwise it will layout the child at the size it was told to. It will squeeze or stretch its children if 
+//    Necessary.
+//
+// However there is a catch. Some html components like block frames can not determine their preferred size. 
+// this is their size if they were laid out intrinsically. So the box will flow the child to determine this can
+// cache the value.
+
+// Boxes and Incremental Reflow
+// ----------------------------
+// Boxes layout out top down by adding up their children's min, max, and preferred sizes. Only problem is if a incremental
+// reflow occurs. The preferred size of a child deep in the hierarchy could change. And this could change
+// any number of syblings around the box. Basically any children in the reflow chain must have their caches cleared
+// so when asked for there current size they can relayout themselves. 
+
+#include "nsBoxFrame.h"
+
+#include "gfxUtils.h"
+#include "mozilla/gfx/2D.h"
+#include "nsBoxLayoutState.h"
+#include "mozilla/dom/Touch.h"
+#include "mozilla/Move.h"
+#include "nsStyleContext.h"
+#include "nsPlaceholderFrame.h"
+#include "nsPresContext.h"
+#include "nsCOMPtr.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+#include "nsHTMLParts.h"
+#include "nsViewManager.h"
+#include "nsView.h"
+#include "nsIPresShell.h"
+#include "nsCSSRendering.h"
+#include "nsIServiceManager.h"
+#include "nsBoxLayout.h"
+#include "nsSprocketLayout.h"
+#include "nsIScrollableFrame.h"
+#include "nsWidgetsCID.h"
+#include "nsCSSAnonBoxes.h"
+#include "nsContainerFrame.h"
+#include "nsIDOMElement.h"
+#include "nsITheme.h"
+#include "nsTransform2D.h"
+#include "mozilla/EventStateManager.h"
+#include "nsIDOMEvent.h"
+#include "nsDisplayList.h"
+#include "mozilla/Preferences.h"
+#include "nsThemeConstants.h"
+#include "nsLayoutUtils.h"
+#include "nsSliderFrame.h"
+#include <algorithm>
+
+// Needed for Print Preview
+#include "nsIURI.h"
+
+#include "mozilla/TouchEvents.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+using namespace mozilla::gfx;
+
+//define DEBUG_REDRAW
+
+#define DEBUG_SPRING_SIZE 8
+#define DEBUG_BORDER_SIZE 2
+#define COIL_SIZE 8
+
+//#define TEST_SANITY
+
+#ifdef DEBUG_rods
+//#define DO_NOISY_REFLOW
+#endif
+
+#ifdef DEBUG_LAYOUT
+bool nsBoxFrame::gDebug = false;
+nsIFrame* nsBoxFrame::mDebugChild = nullptr;
+#endif
+
+nsIFrame*
+NS_NewBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext, bool aIsRoot, nsBoxLayout* aLayoutManager)
+{
+  return new (aPresShell) nsBoxFrame(aContext, aIsRoot, aLayoutManager);
+}
+
+nsIFrame*
+NS_NewBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsBoxFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsBoxFrame)
+
+#ifdef DEBUG
+NS_QUERYFRAME_HEAD(nsBoxFrame)
+  NS_QUERYFRAME_ENTRY(nsBoxFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)
+#endif
+
+nsBoxFrame::nsBoxFrame(nsStyleContext* aContext,
+                       bool aIsRoot,
+                       nsBoxLayout* aLayoutManager) :
+  nsContainerFrame(aContext)
+{
+  mState |= NS_STATE_IS_HORIZONTAL;
+  mState |= NS_STATE_AUTO_STRETCH;
+
+  if (aIsRoot) 
+     mState |= NS_STATE_IS_ROOT;
+
+  mValign = vAlign_Top;
+  mHalign = hAlign_Left;
+  
+  // if no layout manager specified us the static sprocket layout
+  nsCOMPtr<nsBoxLayout> layout = aLayoutManager;
+
+  if (layout == nullptr) {
+    NS_NewSprocketLayout(layout);
+  }
+
+  SetXULLayoutManager(layout);
+}
+
+nsBoxFrame::~nsBoxFrame()
+{
+}
+
+void
+nsBoxFrame::SetInitialChildList(ChildListID     aListID,
+                                nsFrameList&    aChildList)
+{
+  nsContainerFrame::SetInitialChildList(aListID, aChildList);
+  if (aListID == kPrincipalList) {
+    // initialize our list of infos.
+    nsBoxLayoutState state(PresContext());
+    CheckBoxOrder();
+    if (mLayoutManager)
+      mLayoutManager->ChildrenSet(this, state, mFrames.FirstChild());
+  }
+}
+
+/* virtual */ void
+nsBoxFrame::DidSetStyleContext(nsStyleContext* aOldStyleContext)
+{
+  nsContainerFrame::DidSetStyleContext(aOldStyleContext);
+
+  // The values that CacheAttributes() computes depend on our style,
+  // so we need to recompute them here...
+  CacheAttributes();
+}
+
+/**
+ * Initialize us. This is a good time to get the alignment of the box
+ */
+void
+nsBoxFrame::Init(nsIContent*       aContent,
+                 nsContainerFrame* aParent,
+                 nsIFrame*         aPrevInFlow)
+{
+  nsContainerFrame::Init(aContent, aParent, aPrevInFlow);
+
+  if (GetStateBits() & NS_FRAME_FONT_INFLATION_CONTAINER) {
+    AddStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT);
+  }
+
+  MarkIntrinsicISizesDirty();
+
+  CacheAttributes();
+
+#ifdef DEBUG_LAYOUT
+    // if we are root and this
+  if (mState & NS_STATE_IS_ROOT) {
+    GetDebugPref();
+  }
+#endif
+
+  UpdateMouseThrough();
+
+  // register access key
+  RegUnregAccessKey(true);
+}
+
+void nsBoxFrame::UpdateMouseThrough()
+{
+  if (mContent) {
+    static nsIContent::AttrValuesArray strings[] =
+      {&nsGkAtoms::never, &nsGkAtoms::always, nullptr};
+    switch (mContent->FindAttrValueIn(kNameSpaceID_None,
+              nsGkAtoms::mousethrough, strings, eCaseMatters)) {
+      case 0: AddStateBits(NS_FRAME_MOUSE_THROUGH_NEVER); break;
+      case 1: AddStateBits(NS_FRAME_MOUSE_THROUGH_ALWAYS); break;
+      case 2: {
+        RemoveStateBits(NS_FRAME_MOUSE_THROUGH_ALWAYS);
+        RemoveStateBits(NS_FRAME_MOUSE_THROUGH_NEVER);
+        break;
+      }
+    }
+  }
+}
+
+void
+nsBoxFrame::CacheAttributes()
+{
+  /*
+  printf("Caching: ");
+  XULDumpBox(stdout);
+  printf("\n");
+   */
+
+  mValign = vAlign_Top;
+  mHalign = hAlign_Left;
+
+  bool orient = false;
+  GetInitialOrientation(orient); 
+  if (orient)
+    mState |= NS_STATE_IS_HORIZONTAL;
+  else
+    mState &= ~NS_STATE_IS_HORIZONTAL;
+
+  bool normal = true;
+  GetInitialDirection(normal); 
+  if (normal)
+    mState |= NS_STATE_IS_DIRECTION_NORMAL;
+  else
+    mState &= ~NS_STATE_IS_DIRECTION_NORMAL;
+
+  GetInitialVAlignment(mValign);
+  GetInitialHAlignment(mHalign);
+  
+  bool equalSize = false;
+  GetInitialEqualSize(equalSize); 
+  if (equalSize)
+        mState |= NS_STATE_EQUAL_SIZE;
+    else
+        mState &= ~NS_STATE_EQUAL_SIZE;
+
+  bool autostretch = !!(mState & NS_STATE_AUTO_STRETCH);
+  GetInitialAutoStretch(autostretch);
+  if (autostretch)
+        mState |= NS_STATE_AUTO_STRETCH;
+     else
+        mState &= ~NS_STATE_AUTO_STRETCH;
+
+
+#ifdef DEBUG_LAYOUT
+  bool debug = mState & NS_STATE_SET_TO_DEBUG;
+  bool debugSet = GetInitialDebug(debug); 
+  if (debugSet) {
+        mState |= NS_STATE_DEBUG_WAS_SET;
+        if (debug)
+            mState |= NS_STATE_SET_TO_DEBUG;
+        else
+            mState &= ~NS_STATE_SET_TO_DEBUG;
+  } else {
+        mState &= ~NS_STATE_DEBUG_WAS_SET;
+  }
+#endif
+}
+
+#ifdef DEBUG_LAYOUT
+bool
+nsBoxFrame::GetInitialDebug(bool& aDebug)
+{
+  if (!GetContent())
+    return false;
+
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::_false, &nsGkAtoms::_true, nullptr};
+  int32_t index = GetContent()->FindAttrValueIn(kNameSpaceID_None,
+      nsGkAtoms::debug, strings, eCaseMatters);
+  if (index >= 0) {
+    aDebug = index == 1;
+    return true;
+  }
+
+  return false;
+}
+#endif
+
+bool
+nsBoxFrame::GetInitialHAlignment(nsBoxFrame::Halignment& aHalign)
+{
+  if (!GetContent())
+    return false;
+
+  // XXXdwh Everything inside this if statement is deprecated code.
+  static nsIContent::AttrValuesArray alignStrings[] =
+    {&nsGkAtoms::left, &nsGkAtoms::right, nullptr};
+  static const Halignment alignValues[] = {hAlign_Left, hAlign_Right};
+  int32_t index = GetContent()->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::align,
+      alignStrings, eCaseMatters);
+  if (index >= 0) {
+    aHalign = alignValues[index];
+    return true;
+  }
+      
+  // Now that the deprecated stuff is out of the way, we move on to check the appropriate 
+  // attribute.  For horizontal boxes, we are checking the PACK attribute.  For vertical boxes
+  // we are checking the ALIGN attribute.
+  nsIAtom* attrName = IsXULHorizontal() ? nsGkAtoms::pack : nsGkAtoms::align;
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::_empty, &nsGkAtoms::start, &nsGkAtoms::center, &nsGkAtoms::end, nullptr};
+  static const Halignment values[] =
+    {hAlign_Left/*not used*/, hAlign_Left, hAlign_Center, hAlign_Right};
+  index = GetContent()->FindAttrValueIn(kNameSpaceID_None, attrName,
+      strings, eCaseMatters);
+
+  if (index == nsIContent::ATTR_VALUE_NO_MATCH) {
+    // The attr was present but had a nonsensical value. Revert to the default.
+    return false;
+  }
+  if (index > 0) {    
+    aHalign = values[index];
+    return true;
+  }
+
+  // Now that we've checked for the attribute it's time to check CSS.  For 
+  // horizontal boxes we're checking PACK.  For vertical boxes we are checking
+  // ALIGN.
+  const nsStyleXUL* boxInfo = StyleXUL();
+  if (IsXULHorizontal()) {
+    switch (boxInfo->mBoxPack) {
+      case StyleBoxPack::Start:
+        aHalign = nsBoxFrame::hAlign_Left;
+        return true;
+      case StyleBoxPack::Center:
+        aHalign = nsBoxFrame::hAlign_Center;
+        return true;
+      case StyleBoxPack::End:
+        aHalign = nsBoxFrame::hAlign_Right;
+        return true;
+      default: // Nonsensical value. Just bail.
+        return false;
+    }
+  }
+  else {
+    switch (boxInfo->mBoxAlign) {
+      case StyleBoxAlign::Start:
+        aHalign = nsBoxFrame::hAlign_Left;
+        return true;
+      case StyleBoxAlign::Center:
+        aHalign = nsBoxFrame::hAlign_Center;
+        return true;
+      case StyleBoxAlign::End:
+        aHalign = nsBoxFrame::hAlign_Right;
+        return true;
+      default: // Nonsensical value. Just bail.
+        return false;
+    }
+  }
+
+  return false;
+}
+
+bool
+nsBoxFrame::GetInitialVAlignment(nsBoxFrame::Valignment& aValign)
+{
+  if (!GetContent())
+    return false;
+
+  static nsIContent::AttrValuesArray valignStrings[] =
+    {&nsGkAtoms::top, &nsGkAtoms::baseline, &nsGkAtoms::middle, &nsGkAtoms::bottom, nullptr};
+  static const Valignment valignValues[] =
+    {vAlign_Top, vAlign_BaseLine, vAlign_Middle, vAlign_Bottom};
+  int32_t index = GetContent()->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::valign,
+      valignStrings, eCaseMatters);
+  if (index >= 0) {
+    aValign = valignValues[index];
+    return true;
+  }
+
+  // Now that the deprecated stuff is out of the way, we move on to check the appropriate 
+  // attribute.  For horizontal boxes, we are checking the ALIGN attribute.  For vertical boxes
+  // we are checking the PACK attribute.
+  nsIAtom* attrName = IsXULHorizontal() ? nsGkAtoms::align : nsGkAtoms::pack;
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::_empty, &nsGkAtoms::start, &nsGkAtoms::center,
+     &nsGkAtoms::baseline, &nsGkAtoms::end, nullptr};
+  static const Valignment values[] =
+    {vAlign_Top/*not used*/, vAlign_Top, vAlign_Middle, vAlign_BaseLine, vAlign_Bottom};
+  index = GetContent()->FindAttrValueIn(kNameSpaceID_None, attrName,
+      strings, eCaseMatters);
+  if (index == nsIContent::ATTR_VALUE_NO_MATCH) {
+    // The attr was present but had a nonsensical value. Revert to the default.
+    return false;
+  }
+  if (index > 0) {
+    aValign = values[index];
+    return true;
+  }
+
+  // Now that we've checked for the attribute it's time to check CSS.  For 
+  // horizontal boxes we're checking ALIGN.  For vertical boxes we are checking
+  // PACK.
+  const nsStyleXUL* boxInfo = StyleXUL();
+  if (IsXULHorizontal()) {
+    switch (boxInfo->mBoxAlign) {
+      case StyleBoxAlign::Start:
+        aValign = nsBoxFrame::vAlign_Top;
+        return true;
+      case StyleBoxAlign::Center:
+        aValign = nsBoxFrame::vAlign_Middle;
+        return true;
+      case StyleBoxAlign::Baseline:
+        aValign = nsBoxFrame::vAlign_BaseLine;
+        return true;
+      case StyleBoxAlign::End:
+        aValign = nsBoxFrame::vAlign_Bottom;
+        return true;
+      default: // Nonsensical value. Just bail.
+        return false;
+    }
+  }
+  else {
+    switch (boxInfo->mBoxPack) {
+      case StyleBoxPack::Start:
+        aValign = nsBoxFrame::vAlign_Top;
+        return true;
+      case StyleBoxPack::Center:
+        aValign = nsBoxFrame::vAlign_Middle;
+        return true;
+      case StyleBoxPack::End:
+        aValign = nsBoxFrame::vAlign_Bottom;
+        return true;
+      default: // Nonsensical value. Just bail.
+        return false;
+    }
+  }
+
+  return false;
+}
+
+void
+nsBoxFrame::GetInitialOrientation(bool& aIsHorizontal)
+{
+ // see if we are a vertical or horizontal box.
+  if (!GetContent())
+    return;
+
+  // Check the style system first.
+  const nsStyleXUL* boxInfo = StyleXUL();
+  if (boxInfo->mBoxOrient == StyleBoxOrient::Horizontal) {
+    aIsHorizontal = true;
+  } else {
+    aIsHorizontal = false;
+  }
+
+  // Now see if we have an attribute.  The attribute overrides
+  // the style system value.
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::vertical, &nsGkAtoms::horizontal, nullptr};
+  int32_t index = GetContent()->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::orient,
+      strings, eCaseMatters);
+  if (index >= 0) {
+    aIsHorizontal = index == 1;
+  }
+}
+
+void
+nsBoxFrame::GetInitialDirection(bool& aIsNormal)
+{
+  if (!GetContent())
+    return;
+
+  if (IsXULHorizontal()) {
+    // For horizontal boxes only, we initialize our value based off the CSS 'direction' property.
+    // This means that BiDI users will end up with horizontally inverted chrome.
+    aIsNormal = (StyleVisibility()->mDirection == NS_STYLE_DIRECTION_LTR); // If text runs RTL then so do we.
+  }
+  else
+    aIsNormal = true; // Assume a normal direction in the vertical case.
+
+  // Now check the style system to see if we should invert aIsNormal.
+  const nsStyleXUL* boxInfo = StyleXUL();
+  if (boxInfo->mBoxDirection == StyleBoxDirection::Reverse) {
+    aIsNormal = !aIsNormal; // Invert our direction.
+  }
+
+  // Now see if we have an attribute.  The attribute overrides
+  // the style system value.
+  if (IsXULHorizontal()) {
+    static nsIContent::AttrValuesArray strings[] =
+      {&nsGkAtoms::reverse, &nsGkAtoms::ltr, &nsGkAtoms::rtl, nullptr};
+    int32_t index = GetContent()->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::dir,
+        strings, eCaseMatters);
+    if (index >= 0) {
+      bool values[] = {!aIsNormal, true, false};
+      aIsNormal = values[index];
+    }
+  } else if (GetContent()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::dir,
+                                       nsGkAtoms::reverse, eCaseMatters)) {
+    aIsNormal = !aIsNormal;
+  }
+}
+
+/* Returns true if it was set.
+ */
+bool
+nsBoxFrame::GetInitialEqualSize(bool& aEqualSize)
+{
+ // see if we are a vertical or horizontal box.
+  if (!GetContent())
+     return false;
+
+  if (GetContent()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::equalsize,
+                           nsGkAtoms::always, eCaseMatters)) {
+    aEqualSize = true;
+    return true;
+  }
+
+  return false;
+}
+
+/* Returns true if it was set.
+ */
+bool
+nsBoxFrame::GetInitialAutoStretch(bool& aStretch)
+{
+  if (!GetContent())
+     return false;
+  
+  // Check the align attribute.
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::_empty, &nsGkAtoms::stretch, nullptr};
+  int32_t index = GetContent()->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::align,
+      strings, eCaseMatters);
+  if (index != nsIContent::ATTR_MISSING && index != 0) {
+    aStretch = index == 1;
+    return true;
+  }
+
+  // Check the CSS box-align property.
+  const nsStyleXUL* boxInfo = StyleXUL();
+  aStretch = (boxInfo->mBoxAlign == StyleBoxAlign::Stretch);
+
+  return true;
+}
+
+void
+nsBoxFrame::DidReflow(nsPresContext*           aPresContext,
+                      const ReflowInput*  aReflowInput,
+                      nsDidReflowStatus         aStatus)
+{
+  nsFrameState preserveBits =
+    mState & (NS_FRAME_IS_DIRTY | NS_FRAME_HAS_DIRTY_CHILDREN);
+  nsFrame::DidReflow(aPresContext, aReflowInput, aStatus);
+  mState |= preserveBits;
+}
+
+bool
+nsBoxFrame::HonorPrintBackgroundSettings()
+{
+  return (!mContent || !mContent->IsInNativeAnonymousSubtree()) &&
+    nsContainerFrame::HonorPrintBackgroundSettings();
+}
+
+#ifdef DO_NOISY_REFLOW
+static int myCounter = 0;
+static void printSize(char * aDesc, nscoord aSize) 
+{
+  printf(" %s: ", aDesc);
+  if (aSize == NS_UNCONSTRAINEDSIZE) {
+    printf("UC");
+  } else {
+    printf("%d", aSize);
+  }
+}
+#endif
+
+/* virtual */ nscoord
+nsBoxFrame::GetMinISize(nsRenderingContext *aRenderingContext)
+{
+  nscoord result;
+  DISPLAY_MIN_WIDTH(this, result);
+
+  nsBoxLayoutState state(PresContext(), aRenderingContext);
+  nsSize minSize = GetXULMinSize(state);
+
+  // GetXULMinSize returns border-box width, and we want to return content
+  // width.  Since Reflow uses the reflow state's border and padding, we
+  // actually just want to subtract what GetXULMinSize added, which is the
+  // result of GetXULBorderAndPadding.
+  nsMargin bp;
+  GetXULBorderAndPadding(bp);
+
+  result = minSize.width - bp.LeftRight();
+  result = std::max(result, 0);
+
+  return result;
+}
+
+/* virtual */ nscoord
+nsBoxFrame::GetPrefISize(nsRenderingContext *aRenderingContext)
+{
+  nscoord result;
+  DISPLAY_PREF_WIDTH(this, result);
+
+  nsBoxLayoutState state(PresContext(), aRenderingContext);
+  nsSize prefSize = GetXULPrefSize(state);
+
+  // GetXULPrefSize returns border-box width, and we want to return content
+  // width.  Since Reflow uses the reflow state's border and padding, we
+  // actually just want to subtract what GetXULPrefSize added, which is the
+  // result of GetXULBorderAndPadding.
+  nsMargin bp;
+  GetXULBorderAndPadding(bp);
+
+  result = prefSize.width - bp.LeftRight();
+  result = std::max(result, 0);
+
+  return result;
+}
+
+void
+nsBoxFrame::Reflow(nsPresContext*          aPresContext,
+                   ReflowOutput&     aDesiredSize,
+                   const ReflowInput& aReflowInput,
+                   nsReflowStatus&          aStatus)
+{
+  MarkInReflow();
+  // If you make changes to this method, please keep nsLeafBoxFrame::Reflow
+  // in sync, if the changes are applicable there.
+
+  DO_GLOBAL_REFLOW_COUNT("nsBoxFrame");
+  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
+
+  NS_ASSERTION(aReflowInput.ComputedWidth() >=0 &&
+               aReflowInput.ComputedHeight() >= 0, "Computed Size < 0");
+
+#ifdef DO_NOISY_REFLOW
+  printf("\n-------------Starting BoxFrame Reflow ----------------------------\n");
+  printf("%p ** nsBF::Reflow %d ", this, myCounter++);
+  
+  printSize("AW", aReflowInput.AvailableWidth());
+  printSize("AH", aReflowInput.AvailableHeight());
+  printSize("CW", aReflowInput.ComputedWidth());
+  printSize("CH", aReflowInput.ComputedHeight());
+
+  printf(" *\n");
+
+#endif
+
+  aStatus = NS_FRAME_COMPLETE;
+
+  // create the layout state
+  nsBoxLayoutState state(aPresContext, aReflowInput.mRenderingContext,
+                         &aReflowInput, aReflowInput.mReflowDepth);
+
+  WritingMode wm = aReflowInput.GetWritingMode();
+  LogicalSize computedSize(wm, aReflowInput.ComputedISize(),
+                           aReflowInput.ComputedBSize());
+
+  LogicalMargin m = aReflowInput.ComputedLogicalBorderPadding();
+  // GetXULBorderAndPadding(m);
+
+  LogicalSize prefSize(wm);
+
+  // if we are told to layout intrinsic then get our preferred size.
+  NS_ASSERTION(computedSize.ISize(wm) != NS_INTRINSICSIZE,
+               "computed inline size should always be computed");
+  if (computedSize.BSize(wm) == NS_INTRINSICSIZE) {
+    nsSize physicalPrefSize = GetXULPrefSize(state);
+    nsSize minSize = GetXULMinSize(state);
+    nsSize maxSize = GetXULMaxSize(state);
+    // XXXbz isn't GetXULPrefSize supposed to bounds-check for us?
+    physicalPrefSize = BoundsCheck(minSize, physicalPrefSize, maxSize);
+    prefSize = LogicalSize(wm, physicalPrefSize);
+  }
+
+  // get our desiredSize
+  computedSize.ISize(wm) += m.IStart(wm) + m.IEnd(wm);
+
+  if (aReflowInput.ComputedBSize() == NS_INTRINSICSIZE) {
+    computedSize.BSize(wm) = prefSize.BSize(wm);
+    // prefSize is border-box but min/max constraints are content-box.
+    nscoord blockDirBorderPadding =
+      aReflowInput.ComputedLogicalBorderPadding().BStartEnd(wm);
+    nscoord contentBSize = computedSize.BSize(wm) - blockDirBorderPadding;
+    // Note: contentHeight might be negative, but that's OK because min-height
+    // is never negative.
+    computedSize.BSize(wm) = aReflowInput.ApplyMinMaxHeight(contentBSize) +
+                             blockDirBorderPadding;
+  } else {
+    computedSize.BSize(wm) += m.BStart(wm) + m.BEnd(wm);
+  }
+
+  nsSize physicalSize = computedSize.GetPhysicalSize(wm);
+  nsRect r(mRect.x, mRect.y, physicalSize.width, physicalSize.height);
+
+  SetXULBounds(state, r);
+ 
+  // layout our children
+  XULLayout(state);
+  
+  // ok our child could have gotten bigger. So lets get its bounds
+  
+  // get the ascent
+  LogicalSize boxSize = GetLogicalSize(wm);
+  nscoord ascent = boxSize.BSize(wm);
+
+  // getting the ascent could be a lot of work. Don't get it if
+  // we are the root. The viewport doesn't care about it.
+  if (!(mState & NS_STATE_IS_ROOT)) {
+    ascent = GetXULBoxAscent(state);
+  }
+
+  aDesiredSize.SetSize(wm, boxSize);
+  aDesiredSize.SetBlockStartAscent(ascent);
+
+  aDesiredSize.mOverflowAreas = GetOverflowAreas();
+
+#ifdef DO_NOISY_REFLOW
+  {
+    printf("%p ** nsBF(done) W:%d H:%d  ", this, aDesiredSize.Width(), aDesiredSize.Height());
+
+    if (maxElementSize) {
+      printf("MW:%d\n", *maxElementWidth); 
+    } else {
+      printf("MW:?\n"); 
+    }
+
+  }
+#endif
+
+  ReflowAbsoluteFrames(aPresContext, aDesiredSize, aReflowInput, aStatus);
+
+  NS_FRAME_SET_TRUNCATION(aStatus, aReflowInput, aDesiredSize);
+}
+
+nsSize
+nsBoxFrame::GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState)
+{
+  NS_ASSERTION(aBoxLayoutState.GetRenderingContext(),
+               "must have rendering context");
+
+  nsSize size(0,0);
+  DISPLAY_PREF_SIZE(this, size);
+  if (!DoesNeedRecalc(mPrefSize)) {
+     return mPrefSize;
+  }
+
+#ifdef DEBUG_LAYOUT
+  PropagateDebug(aBoxLayoutState);
+#endif
+
+  if (IsXULCollapsed())
+    return size;
+
+  // if the size was not completely redefined in CSS then ask our children
+  bool widthSet, heightSet;
+  if (!nsIFrame::AddXULPrefSize(this, size, widthSet, heightSet))
+  {
+    if (mLayoutManager) {
+      nsSize layoutSize = mLayoutManager->GetXULPrefSize(this, aBoxLayoutState);
+      if (!widthSet)
+        size.width = layoutSize.width;
+      if (!heightSet)
+        size.height = layoutSize.height;
+    }
+    else {
+      size = nsBox::GetXULPrefSize(aBoxLayoutState);
+    }
+  }
+
+  nsSize minSize = GetXULMinSize(aBoxLayoutState);
+  nsSize maxSize = GetXULMaxSize(aBoxLayoutState);
+  mPrefSize = BoundsCheck(minSize, size, maxSize);
+ 
+  return mPrefSize;
+}
+
+nscoord
+nsBoxFrame::GetXULBoxAscent(nsBoxLayoutState& aBoxLayoutState)
+{
+  if (!DoesNeedRecalc(mAscent))
+     return mAscent;
+
+#ifdef DEBUG_LAYOUT
+  PropagateDebug(aBoxLayoutState);
+#endif
+
+  if (IsXULCollapsed())
+    return 0;
+
+  if (mLayoutManager)
+    mAscent = mLayoutManager->GetAscent(this, aBoxLayoutState);
+  else
+    mAscent = nsBox::GetXULBoxAscent(aBoxLayoutState);
+
+  return mAscent;
+}
+
+nsSize
+nsBoxFrame::GetXULMinSize(nsBoxLayoutState& aBoxLayoutState)
+{
+  NS_ASSERTION(aBoxLayoutState.GetRenderingContext(),
+               "must have rendering context");
+
+  nsSize size(0,0);
+  DISPLAY_MIN_SIZE(this, size);
+  if (!DoesNeedRecalc(mMinSize)) {
+    return mMinSize;
+  }
+
+#ifdef DEBUG_LAYOUT
+  PropagateDebug(aBoxLayoutState);
+#endif
+
+  if (IsXULCollapsed())
+    return size;
+
+  // if the size was not completely redefined in CSS then ask our children
+  bool widthSet, heightSet;
+  if (!nsIFrame::AddXULMinSize(aBoxLayoutState, this, size, widthSet, heightSet))
+  {
+    if (mLayoutManager) {
+      nsSize layoutSize = mLayoutManager->GetXULMinSize(this, aBoxLayoutState);
+      if (!widthSet)
+        size.width = layoutSize.width;
+      if (!heightSet)
+        size.height = layoutSize.height;
+    }
+    else {
+      size = nsBox::GetXULMinSize(aBoxLayoutState);
+    }
+  }
+  
+  mMinSize = size;
+
+  return size;
+}
+
+nsSize
+nsBoxFrame::GetXULMaxSize(nsBoxLayoutState& aBoxLayoutState)
+{
+  NS_ASSERTION(aBoxLayoutState.GetRenderingContext(),
+               "must have rendering context");
+
+  nsSize size(NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+  DISPLAY_MAX_SIZE(this, size);
+  if (!DoesNeedRecalc(mMaxSize)) {
+    return mMaxSize;
+  }
+
+#ifdef DEBUG_LAYOUT
+  PropagateDebug(aBoxLayoutState);
+#endif
+
+  if (IsXULCollapsed())
+    return size;
+
+  // if the size was not completely redefined in CSS then ask our children
+  bool widthSet, heightSet;
+  if (!nsIFrame::AddXULMaxSize(this, size, widthSet, heightSet))
+  {
+    if (mLayoutManager) {
+      nsSize layoutSize = mLayoutManager->GetXULMaxSize(this, aBoxLayoutState);
+      if (!widthSet)
+        size.width = layoutSize.width;
+      if (!heightSet)
+        size.height = layoutSize.height;
+    }
+    else {
+      size = nsBox::GetXULMaxSize(aBoxLayoutState);
+    }
+  }
+
+  mMaxSize = size;
+
+  return size;
+}
+
+nscoord
+nsBoxFrame::GetXULFlex()
+{
+  if (!DoesNeedRecalc(mFlex))
+     return mFlex;
+
+  mFlex = nsBox::GetXULFlex();
+
+  return mFlex;
+}
+
+/**
+ * If subclassing please subclass this method not layout. 
+ * layout will call this method.
+ */
+NS_IMETHODIMP
+nsBoxFrame::DoXULLayout(nsBoxLayoutState& aState)
+{
+  uint32_t oldFlags = aState.LayoutFlags();
+  aState.SetLayoutFlags(0);
+
+  nsresult rv = NS_OK;
+  if (mLayoutManager) {
+    CoordNeedsRecalc(mAscent);
+    rv = mLayoutManager->XULLayout(this, aState);
+  }
+
+  aState.SetLayoutFlags(oldFlags);
+
+  if (HasAbsolutelyPositionedChildren()) {
+    // Set up a |reflowInput| to pass into ReflowAbsoluteFrames
+    WritingMode wm = GetWritingMode();
+    ReflowInput reflowInput(aState.PresContext(), this,
+                                  aState.GetRenderingContext(),
+                                  LogicalSize(wm, GetLogicalSize().ISize(wm),
+                                              NS_UNCONSTRAINEDSIZE));
+
+    // Set up a |desiredSize| to pass into ReflowAbsoluteFrames
+    ReflowOutput desiredSize(reflowInput);
+    desiredSize.Width() = mRect.width;
+    desiredSize.Height() = mRect.height;
+
+    // get the ascent (cribbed from ::Reflow)
+    nscoord ascent = mRect.height;
+
+    // getting the ascent could be a lot of work. Don't get it if
+    // we are the root. The viewport doesn't care about it.
+    if (!(mState & NS_STATE_IS_ROOT)) {
+      ascent = GetXULBoxAscent(aState);
+    }
+    desiredSize.SetBlockStartAscent(ascent);
+    desiredSize.mOverflowAreas = GetOverflowAreas();
+
+    AddStateBits(NS_FRAME_IN_REFLOW);
+    // Set up a |reflowStatus| to pass into ReflowAbsoluteFrames
+    // (just a dummy value; hopefully that's OK)
+    nsReflowStatus reflowStatus = NS_FRAME_COMPLETE;
+    ReflowAbsoluteFrames(aState.PresContext(), desiredSize,
+                         reflowInput, reflowStatus);
+    RemoveStateBits(NS_FRAME_IN_REFLOW);
+  }
+
+  return rv;
+}
+
+void
+nsBoxFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  // unregister access key
+  RegUnregAccessKey(false);
+
+  // clean up the container box's layout manager and child boxes
+  SetXULLayoutManager(nullptr);
+
+  nsContainerFrame::DestroyFrom(aDestructRoot);
+} 
+
+#ifdef DEBUG_LAYOUT
+nsresult
+nsBoxFrame::SetXULDebug(nsBoxLayoutState& aState, bool aDebug)
+{
+  // see if our state matches the given debug state
+  bool debugSet = mState & NS_STATE_CURRENTLY_IN_DEBUG;
+  bool debugChanged = (!aDebug && debugSet) || (aDebug && !debugSet);
+
+  // if it doesn't then tell each child below us the new debug state
+  if (debugChanged)
+  {
+     if (aDebug) {
+         mState |= NS_STATE_CURRENTLY_IN_DEBUG;
+     } else {
+         mState &= ~NS_STATE_CURRENTLY_IN_DEBUG;
+     }
+ 
+     SetDebugOnChildList(aState, mFirstChild, aDebug);
+
+    MarkIntrinsicISizesDirty();
+  }
+
+  return NS_OK;
+}
+#endif
+
+/* virtual */ void
+nsBoxFrame::MarkIntrinsicISizesDirty()
+{
+  SizeNeedsRecalc(mPrefSize);
+  SizeNeedsRecalc(mMinSize);
+  SizeNeedsRecalc(mMaxSize);
+  CoordNeedsRecalc(mFlex);
+  CoordNeedsRecalc(mAscent);
+
+  if (mLayoutManager) {
+    nsBoxLayoutState state(PresContext());
+    mLayoutManager->IntrinsicISizesDirty(this, state);
+  }
+
+  // Don't call base class method, since everything it does is within an
+  // IsXULBoxWrapped check.
+}
+
+void
+nsBoxFrame::RemoveFrame(ChildListID     aListID,
+                        nsIFrame*       aOldFrame)
+{
+  NS_PRECONDITION(aListID == kPrincipalList, "We don't support out-of-flow kids");
+  nsPresContext* presContext = PresContext();
+  nsBoxLayoutState state(presContext);
+
+  // remove the child frame
+  mFrames.RemoveFrame(aOldFrame);
+
+  // notify the layout manager
+  if (mLayoutManager)
+    mLayoutManager->ChildrenRemoved(this, state, aOldFrame);
+
+  // destroy the child frame
+  aOldFrame->Destroy();
+
+  // mark us dirty and generate a reflow command
+  PresContext()->PresShell()->
+    FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                     NS_FRAME_HAS_DIRTY_CHILDREN);
+}
+
+void
+nsBoxFrame::InsertFrames(ChildListID     aListID,
+                         nsIFrame*       aPrevFrame,
+                         nsFrameList&    aFrameList)
+{
+   NS_ASSERTION(!aPrevFrame || aPrevFrame->GetParent() == this,
+                "inserting after sibling frame with different parent");
+   NS_ASSERTION(!aPrevFrame || mFrames.ContainsFrame(aPrevFrame),
+                "inserting after sibling frame not in our child list");
+   NS_PRECONDITION(aListID == kPrincipalList, "We don't support out-of-flow kids");
+   nsBoxLayoutState state(PresContext());
+
+   // insert the child frames
+   const nsFrameList::Slice& newFrames =
+     mFrames.InsertFrames(this, aPrevFrame, aFrameList);
+
+   // notify the layout manager
+   if (mLayoutManager)
+     mLayoutManager->ChildrenInserted(this, state, aPrevFrame, newFrames);
+
+   // Make sure to check box order _after_ notifying the layout
+   // manager; otherwise the slice we give the layout manager will
+   // just be bogus.  If the layout manager cares about the order, we
+   // just lose.
+   CheckBoxOrder();
+
+#ifdef DEBUG_LAYOUT
+   // if we are in debug make sure our children are in debug as well.
+   if (mState & NS_STATE_CURRENTLY_IN_DEBUG)
+       SetDebugOnChildList(state, mFrames.FirstChild(), true);
+#endif
+
+   PresContext()->PresShell()->
+     FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                      NS_FRAME_HAS_DIRTY_CHILDREN);
+}
+
+
+void
+nsBoxFrame::AppendFrames(ChildListID     aListID,
+                         nsFrameList&    aFrameList)
+{
+   NS_PRECONDITION(aListID == kPrincipalList, "We don't support out-of-flow kids");
+   nsBoxLayoutState state(PresContext());
+
+   // append the new frames
+   const nsFrameList::Slice& newFrames = mFrames.AppendFrames(this, aFrameList);
+
+   // notify the layout manager
+   if (mLayoutManager)
+     mLayoutManager->ChildrenAppended(this, state, newFrames);
+
+   // Make sure to check box order _after_ notifying the layout
+   // manager; otherwise the slice we give the layout manager will
+   // just be bogus.  If the layout manager cares about the order, we
+   // just lose.
+   CheckBoxOrder();
+
+#ifdef DEBUG_LAYOUT
+   // if we are in debug make sure our children are in debug as well.
+   if (mState & NS_STATE_CURRENTLY_IN_DEBUG)
+       SetDebugOnChildList(state, mFrames.FirstChild(), true);
+#endif
+
+   // XXXbz why is this NS_FRAME_FIRST_REFLOW check here?
+   if (!(GetStateBits() & NS_FRAME_FIRST_REFLOW)) {
+     PresContext()->PresShell()->
+       FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                        NS_FRAME_HAS_DIRTY_CHILDREN);
+   }
+}
+
+/* virtual */ nsContainerFrame*
+nsBoxFrame::GetContentInsertionFrame()
+{
+  if (GetStateBits() & NS_STATE_BOX_WRAPS_KIDS_IN_BLOCK)
+    return PrincipalChildList().FirstChild()->GetContentInsertionFrame();
+  return nsContainerFrame::GetContentInsertionFrame();
+}
+
+nsresult
+nsBoxFrame::AttributeChanged(int32_t aNameSpaceID,
+                             nsIAtom* aAttribute,
+                             int32_t aModType)
+{
+  nsresult rv = nsContainerFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                                   aModType);
+
+  // Ignore 'width', 'height', 'screenX', 'screenY' and 'sizemode' on a
+  // <window>.
+  if (mContent->IsAnyOfXULElements(nsGkAtoms::window,
+                                   nsGkAtoms::page,
+                                   nsGkAtoms::dialog,
+                                   nsGkAtoms::wizard) &&
+      (nsGkAtoms::width == aAttribute ||
+       nsGkAtoms::height == aAttribute ||
+       nsGkAtoms::screenX == aAttribute ||
+       nsGkAtoms::screenY == aAttribute ||
+       nsGkAtoms::sizemode == aAttribute)) {
+    return rv;
+  }
+
+  if (aAttribute == nsGkAtoms::width       ||
+      aAttribute == nsGkAtoms::height      ||
+      aAttribute == nsGkAtoms::align       ||
+      aAttribute == nsGkAtoms::valign      ||
+      aAttribute == nsGkAtoms::left        ||
+      aAttribute == nsGkAtoms::top         ||
+      aAttribute == nsGkAtoms::right        ||
+      aAttribute == nsGkAtoms::bottom       ||
+      aAttribute == nsGkAtoms::start        ||
+      aAttribute == nsGkAtoms::end          ||
+      aAttribute == nsGkAtoms::minwidth     ||
+      aAttribute == nsGkAtoms::maxwidth     ||
+      aAttribute == nsGkAtoms::minheight    ||
+      aAttribute == nsGkAtoms::maxheight    ||
+      aAttribute == nsGkAtoms::flex         ||
+      aAttribute == nsGkAtoms::orient       ||
+      aAttribute == nsGkAtoms::pack         ||
+      aAttribute == nsGkAtoms::dir          ||
+      aAttribute == nsGkAtoms::mousethrough ||
+      aAttribute == nsGkAtoms::equalsize) {
+
+    if (aAttribute == nsGkAtoms::align  ||
+        aAttribute == nsGkAtoms::valign ||
+        aAttribute == nsGkAtoms::orient  ||
+        aAttribute == nsGkAtoms::pack    ||
+#ifdef DEBUG_LAYOUT
+        aAttribute == nsGkAtoms::debug   ||
+#endif
+        aAttribute == nsGkAtoms::dir) {
+
+      mValign = nsBoxFrame::vAlign_Top;
+      mHalign = nsBoxFrame::hAlign_Left;
+
+      bool orient = true;
+      GetInitialOrientation(orient); 
+      if (orient)
+        mState |= NS_STATE_IS_HORIZONTAL;
+      else
+        mState &= ~NS_STATE_IS_HORIZONTAL;
+
+      bool normal = true;
+      GetInitialDirection(normal);
+      if (normal)
+        mState |= NS_STATE_IS_DIRECTION_NORMAL;
+      else
+        mState &= ~NS_STATE_IS_DIRECTION_NORMAL;
+
+      GetInitialVAlignment(mValign);
+      GetInitialHAlignment(mHalign);
+
+      bool equalSize = false;
+      GetInitialEqualSize(equalSize); 
+      if (equalSize)
+        mState |= NS_STATE_EQUAL_SIZE;
+      else
+        mState &= ~NS_STATE_EQUAL_SIZE;
+
+#ifdef DEBUG_LAYOUT
+      bool debug = mState & NS_STATE_SET_TO_DEBUG;
+      bool debugSet = GetInitialDebug(debug);
+      if (debugSet) {
+        mState |= NS_STATE_DEBUG_WAS_SET;
+
+        if (debug)
+          mState |= NS_STATE_SET_TO_DEBUG;
+        else
+          mState &= ~NS_STATE_SET_TO_DEBUG;
+      } else {
+        mState &= ~NS_STATE_DEBUG_WAS_SET;
+      }
+#endif
+
+      bool autostretch = !!(mState & NS_STATE_AUTO_STRETCH);
+      GetInitialAutoStretch(autostretch);
+      if (autostretch)
+        mState |= NS_STATE_AUTO_STRETCH;
+      else
+        mState &= ~NS_STATE_AUTO_STRETCH;
+    }
+    else if (aAttribute == nsGkAtoms::left ||
+             aAttribute == nsGkAtoms::top ||
+             aAttribute == nsGkAtoms::right ||
+             aAttribute == nsGkAtoms::bottom ||
+             aAttribute == nsGkAtoms::start ||
+             aAttribute == nsGkAtoms::end) {
+      mState &= ~NS_STATE_STACK_NOT_POSITIONED;
+    }
+    else if (aAttribute == nsGkAtoms::mousethrough) {
+      UpdateMouseThrough();
+    }
+
+    PresContext()->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
+  }
+  else if (aAttribute == nsGkAtoms::ordinal) {
+    nsIFrame* parent = GetParentXULBox(this);
+    // If our parent is not a box, there's not much we can do... but in that
+    // case our ordinal doesn't matter anyway, so that's ok.
+    // Also don't bother with popup frames since they are kept on the 
+    // kPopupList and XULRelayoutChildAtOrdinal() only handles
+    // principal children.
+    if (parent && !(GetStateBits() & NS_FRAME_OUT_OF_FLOW) &&
+        StyleDisplay()->mDisplay != mozilla::StyleDisplay::Popup) {
+      parent->XULRelayoutChildAtOrdinal(this);
+      // XXXldb Should this instead be a tree change on the child or parent?
+      PresContext()->PresShell()->
+        FrameNeedsReflow(parent, nsIPresShell::eStyleChange,
+                         NS_FRAME_IS_DIRTY);
+    }
+  }
+  // If the accesskey changed, register for the new value
+  // The old value has been unregistered in nsXULElement::SetAttr
+  else if (aAttribute == nsGkAtoms::accesskey) {
+    RegUnregAccessKey(true);
+  }
+  else if (aAttribute == nsGkAtoms::rows &&
+           mContent->IsXULElement(nsGkAtoms::tree)) {
+    // Reflow ourselves and all our children if "rows" changes, since
+    // nsTreeBodyFrame's layout reads this from its parent (this frame).
+    PresContext()->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
+  }
+
+  return rv;
+}
+
+#ifdef DEBUG_LAYOUT
+void
+nsBoxFrame::GetDebugPref()
+{
+  gDebug = Preferences::GetBool("xul.debug.box");
+}
+
+class nsDisplayXULDebug : public nsDisplayItem {
+public:
+  nsDisplayXULDebug(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame) :
+    nsDisplayItem(aBuilder, aFrame) {
+    MOZ_COUNT_CTOR(nsDisplayXULDebug);
+  }
+#ifdef NS_BUILD_REFCNT_LOGGING
+  virtual ~nsDisplayXULDebug() {
+    MOZ_COUNT_DTOR(nsDisplayXULDebug);
+  }
+#endif
+
+  virtual void HitTest(nsDisplayListBuilder* aBuilder, nsRect aRect,
+                       HitTestState* aState, nsTArray<nsIFrame*> *aOutFrames) {
+    nsPoint rectCenter(aRect.x + aRect.width / 2, aRect.y + aRect.height / 2);
+    static_cast<nsBoxFrame*>(mFrame)->
+      DisplayDebugInfoFor(this, rectCenter - ToReferenceFrame());
+    aOutFrames->AppendElement(this);
+  }
+  virtual void Paint(nsDisplayListBuilder* aBuilder
+                     nsRenderingContext* aCtx);
+  NS_DISPLAY_DECL_NAME("XULDebug", TYPE_XUL_DEBUG)
+};
+
+void
+nsDisplayXULDebug::Paint(nsDisplayListBuilder* aBuilder,
+                         nsRenderingContext* aCtx)
+{
+  static_cast<nsBoxFrame*>(mFrame)->
+    PaintXULDebugOverlay(*aCtx->GetDrawTarget(), ToReferenceFrame());
+}
+
+static void
+PaintXULDebugBackground(nsIFrame* aFrame, DrawTarget* aDrawTarget,
+                        const nsRect& aDirtyRect, nsPoint aPt)
+{
+  static_cast<nsBoxFrame*>(aFrame)->PaintXULDebugBackground(aDrawTarget, aPt);
+}
+#endif
+
+void
+nsBoxFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                             const nsRect&           aDirtyRect,
+                             const nsDisplayListSet& aLists)
+{
+  bool forceLayer = false;
+
+  if (GetContent()->IsXULElement()) {
+    // forcelayer is only supported on XUL elements with box layout
+    if (GetContent()->HasAttr(kNameSpaceID_None, nsGkAtoms::layer)) {
+      forceLayer = true;
+    }
+    // Check for frames that are marked as a part of the region used
+    // in calculating glass margins on Windows.
+    const nsStyleDisplay* styles = StyleDisplay();
+    if (styles && styles->mAppearance == NS_THEME_WIN_EXCLUDE_GLASS) {
+      aBuilder->AddWindowExcludeGlassRegion(
+          nsRect(aBuilder->ToReferenceFrame(this), GetSize()));
+    }
+  }
+
+  nsDisplayListCollection tempLists;
+  const nsDisplayListSet& destination = forceLayer ? tempLists : aLists;
+
+  DisplayBorderBackgroundOutline(aBuilder, destination);
+
+#ifdef DEBUG_LAYOUT
+  if (mState & NS_STATE_CURRENTLY_IN_DEBUG) {
+    destination.BorderBackground()->AppendNewToTop(new (aBuilder)
+      nsDisplayGeneric(aBuilder, this, PaintXULDebugBackground,
+                       "XULDebugBackground"));
+    destination.Outlines()->AppendNewToTop(new (aBuilder)
+      nsDisplayXULDebug(aBuilder, this));
+  }
+#endif
+
+  BuildDisplayListForChildren(aBuilder, aDirtyRect, destination);
+
+  // see if we have to draw a selection frame around this container
+  DisplaySelectionOverlay(aBuilder, destination.Content());
+
+  if (forceLayer) {
+    // This is a bit of a hack. Collect up all descendant display items
+    // and merge them into a single Content() list. This can cause us
+    // to violate CSS stacking order, but forceLayer is a magic
+    // XUL-only extension anyway.
+    nsDisplayList masterList;
+    masterList.AppendToTop(tempLists.BorderBackground());
+    masterList.AppendToTop(tempLists.BlockBorderBackgrounds());
+    masterList.AppendToTop(tempLists.Floats());
+    masterList.AppendToTop(tempLists.Content());
+    masterList.AppendToTop(tempLists.PositionedDescendants());
+    masterList.AppendToTop(tempLists.Outlines());
+
+    // Wrap the list to make it its own layer
+    aLists.Content()->AppendNewToTop(new (aBuilder)
+      nsDisplayOwnLayer(aBuilder, this, &masterList));
+  }
+}
+
+void
+nsBoxFrame::BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                        const nsRect&           aDirtyRect,
+                                        const nsDisplayListSet& aLists)
+{
+  nsIFrame* kid = mFrames.FirstChild();
+  // Put each child's background onto the BlockBorderBackgrounds list
+  // to emulate the existing two-layer XUL painting scheme.
+  nsDisplayListSet set(aLists, aLists.BlockBorderBackgrounds());
+  // The children should be in the right order
+  while (kid) {
+    BuildDisplayListForChild(aBuilder, kid, aDirtyRect, set);
+    kid = kid->GetNextSibling();
+  }
+}
+
+// REVIEW: PaintChildren did a few things none of which are a big deal
+// anymore:
+// * Paint some debugging rects for this frame.
+// This is done by nsDisplayXULDebugBackground, which goes in the
+// BorderBackground() layer so it isn't clipped by OVERFLOW_CLIP.
+// * Apply OVERFLOW_CLIP to the children.
+// This is now in nsFrame::BuildDisplayListForStackingContext/Child.
+// * Actually paint the children.
+// Moved to BuildDisplayList.
+// * Paint per-kid debug information.
+// This is done by nsDisplayXULDebug, which is in the Outlines()
+// layer so it goes on top. This means it is not clipped by OVERFLOW_CLIP,
+// whereas it did used to respect OVERFLOW_CLIP, but too bad.
+#ifdef DEBUG_LAYOUT
+void
+nsBoxFrame::PaintXULDebugBackground(DrawTarget* aDrawTarget, nsPoint aPt)
+{
+  nsMargin border;
+  GetXULBorder(border);
+
+  nsMargin debugBorder;
+  nsMargin debugMargin;
+  nsMargin debugPadding;
+
+  bool isHorizontal = IsXULHorizontal();
+
+  GetDebugBorder(debugBorder);
+  PixelMarginToTwips(debugBorder);
+
+  GetDebugMargin(debugMargin);
+  PixelMarginToTwips(debugMargin);
+
+  GetDebugPadding(debugPadding);
+  PixelMarginToTwips(debugPadding);
+
+  nsRect inner(mRect);
+  inner.MoveTo(aPt);
+  inner.Deflate(debugMargin);
+  inner.Deflate(border);
+  //nsRect borderRect(inner);
+
+  int32_t appUnitsPerDevPixel = PresContext()->AppUnitsPerDevPixel();
+
+  ColorPattern color(ToDeviceColor(isHorizontal ? Color(0.f, 0.f, 1.f, 1.f) :
+                                                  Color(1.f, 0.f, 0.f, 1.f)));
+
+  //left
+  nsRect r(inner);
+  r.width = debugBorder.left;
+  aDrawTarget->FillRect(NSRectToRect(r, appUnitsPerDevPixel), color);
+
+  // top
+  r = inner;
+  r.height = debugBorder.top;
+  aDrawTarget->FillRect(NSRectToRect(r, appUnitsPerDevPixel), color);
+
+  //right
+  r = inner;
+  r.x = r.x + r.width - debugBorder.right;
+  r.width = debugBorder.right;
+  aDrawTarget->FillRect(NSRectToRect(r, appUnitsPerDevPixel), color);
+
+  //bottom
+  r = inner;
+  r.y = r.y + r.height - debugBorder.bottom;
+  r.height = debugBorder.bottom;
+  aDrawTarget->FillRect(NSRectToRect(r, appUnitsPerDevPixel), color);
+
+  // If we have dirty children or we are dirty place a green border around us.
+  if (NS_SUBTREE_DIRTY(this)) {
+    nsRect dirty(inner);
+    ColorPattern green(ToDeviceColor(Color(0.f, 1.f, 0.f, 1.f)));
+    aDrawTarget->StrokeRect(NSRectToRect(dirty, appUnitsPerDevPixel), green);
+  }
+}
+
+void
+nsBoxFrame::PaintXULDebugOverlay(DrawTarget& aDrawTarget, nsPoint aPt)
+{
+  nsMargin border;
+  GetXULBorder(border);
+
+  nsMargin debugMargin;
+  GetDebugMargin(debugMargin);
+  PixelMarginToTwips(debugMargin);
+
+  nsRect inner(mRect);
+  inner.MoveTo(aPt);
+  inner.Deflate(debugMargin);
+  inner.Deflate(border);
+
+  nscoord onePixel = GetPresContext()->IntScaledPixelsToTwips(1);
+
+  kid = nsBox::GetChildXULBox(this);
+  while (nullptr != kid) {
+    bool isHorizontal = IsXULHorizontal();
+
+    nscoord x, y, borderSize, spacerSize;
+    
+    nsRect cr(kid->mRect);
+    nsMargin margin;
+    kid->GetXULMargin(margin);
+    cr.Inflate(margin);
+    
+    if (isHorizontal) 
+    {
+        cr.y = inner.y;
+        x = cr.x;
+        y = cr.y + onePixel;
+        spacerSize = debugBorder.top - onePixel*4;
+    } else {
+        cr.x = inner.x;
+        x = cr.y;
+        y = cr.x + onePixel;
+        spacerSize = debugBorder.left - onePixel*4;
+    }
+
+    nscoord flex = kid->GetXULFlex();
+
+    if (!kid->IsXULCollapsed()) {
+      if (isHorizontal) 
+          borderSize = cr.width;
+      else 
+          borderSize = cr.height;
+
+      DrawSpacer(GetPresContext(), aDrawTarget, isHorizontal, flex, x, y, borderSize, spacerSize);
+    }
+
+    kid = GetNextXULBox(kid);
+  }
+}
+#endif
+
+#ifdef DEBUG_LAYOUT
+void
+nsBoxFrame::GetBoxName(nsAutoString& aName)
+{
+   GetFrameName(aName);
+}
+#endif
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+nsBoxFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("Box"), aResult);
+}
+#endif
+
+nsIAtom*
+nsBoxFrame::GetType() const
+{
+  return nsGkAtoms::boxFrame;
+}
+
+#ifdef DEBUG_LAYOUT
+nsresult
+nsBoxFrame::GetXULDebug(bool& aDebug)
+{
+  aDebug = (mState & NS_STATE_CURRENTLY_IN_DEBUG);
+  return NS_OK;
+}
+#endif
+
+// REVIEW: nsBoxFrame::GetFrameForPoint is a problem because of 'mousethrough'
+// attribute support. Here's how it works:
+// * For each child frame F, we determine the target frame T(F) by recursively
+// invoking GetFrameForPoint on the child
+// * Let F' be the last child frame such that T(F') doesn't have mousethrough.
+// If F' exists, return T(F')
+// * Otherwise let F'' be the first child frame such that T(F'') is non-null.
+// If F'' exists, return T(F'')
+// * Otherwise return this frame, if this frame contains the point
+// * Otherwise return null
+// It's not clear how this should work for more complex z-ordering situations.
+// The basic principle seems to be that if a frame F has a descendant
+// 'mousethrough' frame that includes the target position, then F
+// will not receive events (unless it overrides GetFrameForPoint).
+// A 'mousethrough' frame will only receive an event if, after applying that rule,
+// all eligible frames are 'mousethrough'; the bottom-most inner-most 'mousethrough'
+// frame is then chosen (the first eligible frame reached in a
+// traversal of the frame tree --- pre/post is irrelevant since ancestors
+// of the mousethrough frames can't be eligible).
+// IMHO this is very bogus and adds a great deal of complexity for something
+// that is very rarely used. So I'm redefining 'mousethrough' to the following:
+// a frame with mousethrough is transparent to mouse events. This is compatible
+// with the way 'mousethrough' is used in Seamonkey's navigator.xul and
+// Firefox's browser.xul. The only other place it's used is in the 'expander'
+// XBL binding, which in our tree is only used by Thunderbird SMIME Advanced
+// Preferences, and I can't figure out what that does, so I'll have to test it.
+// If it's broken I'll probably just change the binding to use it more sensibly.
+// This new behaviour is implemented in nsDisplayList::HitTest. 
+// REVIEW: This debug-box stuff is annoying. I'm just going to put debug boxes
+// in the outline layer and avoid GetDebugBoxAt.
+
+// REVIEW: GetCursor had debug-only event dumping code. I have replaced it
+// with instrumentation in nsDisplayXULDebug.
+
+#ifdef DEBUG_LAYOUT
+void
+nsBoxFrame::DrawLine(DrawTarget& aDrawTarget, bool aHorizontal, nscoord x1, nscoord y1, nscoord x2, nscoord y2)
+{
+    nsPoint p1(x1, y1);
+    nsPoint p2(x2, y2);
+    if (!aHorizontal) {
+      Swap(p1.x, p1.y);
+      Swap(p2.x, p2.y);
+    }
+    ColorPattern white(ToDeviceColor(Color(1.f, 1.f, 1.f, 1.f)));
+    StrokeLineWithSnapping(p1, p2, PresContext()->AppUnitsPerDevPixel(),
+                           aDrawTarget, color);
+}
+
+void
+nsBoxFrame::FillRect(DrawTarget& aDrawTarget, bool aHorizontal, nscoord x, nscoord y, nscoord width, nscoord height)
+{
+    Rect rect = NSRectToSnappedRect(aHorizontal ? nsRect(x, y, width, height) :
+                                                  nsRect(y, x, height, width),
+                                    PresContext()->AppUnitsPerDevPixel(),
+                                    aDrawTarget);
+    ColorPattern white(ToDeviceColor(Color(1.f, 1.f, 1.f, 1.f)));
+    aDrawTarget.FillRect(rect, white);
+}
+
+void 
+nsBoxFrame::DrawSpacer(nsPresContext* aPresContext, DrawTarget& aDrawTarget,
+                       bool aHorizontal, int32_t flex, nscoord x, nscoord y,
+                       nscoord size, nscoord spacerSize)
+{    
+         nscoord onePixel = aPresContext->IntScaledPixelsToTwips(1);
+
+     // if we do draw the coils
+        int distance = 0;
+        int center = 0;
+        int offset = 0;
+        int coilSize = COIL_SIZE*onePixel;
+        int halfSpacer = spacerSize/2;
+
+        distance = size;
+        center = y + halfSpacer;
+        offset = x;
+
+        int coils = distance/coilSize;
+
+        int halfCoilSize = coilSize/2;
+
+        if (flex == 0) {
+            DrawLine(aDrawTarget, aHorizontal, x,y + spacerSize/2, x + size, y + spacerSize/2);
+        } else {
+            for (int i=0; i < coils; i++)
+            {
+                   DrawLine(aDrawTarget, aHorizontal, offset, center+halfSpacer, offset+halfCoilSize, center-halfSpacer);
+                   DrawLine(aDrawTarget, aHorizontal, offset+halfCoilSize, center-halfSpacer, offset+coilSize, center+halfSpacer);
+
+                   offset += coilSize;
+            }
+        }
+
+        FillRect(aDrawTarget, aHorizontal, x + size - spacerSize/2, y, spacerSize/2, spacerSize);
+        FillRect(aDrawTarget, aHorizontal, x, y, spacerSize/2, spacerSize);
+}
+
+void
+nsBoxFrame::GetDebugBorder(nsMargin& aInset)
+{
+    aInset.SizeTo(2,2,2,2);
+
+    if (IsXULHorizontal()) 
+       aInset.top = 10;
+    else 
+       aInset.left = 10;
+}
+
+void
+nsBoxFrame::GetDebugMargin(nsMargin& aInset)
+{
+    aInset.SizeTo(2,2,2,2);
+}
+
+void
+nsBoxFrame::GetDebugPadding(nsMargin& aPadding)
+{
+    aPadding.SizeTo(2,2,2,2);
+}
+
+void 
+nsBoxFrame::PixelMarginToTwips(nsMargin& aMarginPixels)
+{
+  nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
+  aMarginPixels.left   *= onePixel;
+  aMarginPixels.right  *= onePixel;
+  aMarginPixels.top    *= onePixel;
+  aMarginPixels.bottom *= onePixel;
+}
+
+void
+nsBoxFrame::GetValue(nsPresContext* aPresContext, const nsSize& a, const nsSize& b, char* ch) 
+{
+    float p2t = aPresContext->ScaledPixelsToTwips();
+
+    char width[100];
+    char height[100];
+    
+    if (a.width == NS_INTRINSICSIZE)
+        sprintf(width,"%s","INF");
+    else
+        sprintf(width,"%d", nscoord(a.width/*/p2t*/));
+    
+    if (a.height == NS_INTRINSICSIZE)
+        sprintf(height,"%s","INF");
+    else 
+        sprintf(height,"%d", nscoord(a.height/*/p2t*/));
+    
+
+    sprintf(ch, "(%s%s, %s%s)", width, (b.width != NS_INTRINSICSIZE ? "[SET]" : ""),
+                    height, (b.height != NS_INTRINSICSIZE ? "[SET]" : ""));
+
+}
+
+void
+nsBoxFrame::GetValue(nsPresContext* aPresContext, int32_t a, int32_t b, char* ch) 
+{
+    if (a == NS_INTRINSICSIZE)
+      sprintf(ch, "%d[SET]", b);             
+    else
+      sprintf(ch, "%d", a);             
+}
+
+nsresult
+nsBoxFrame::DisplayDebugInfoFor(nsIFrame*  aBox,
+                                nsPoint& aPoint)
+{
+    nsBoxLayoutState state(GetPresContext());
+
+    nscoord x = aPoint.x;
+    nscoord y = aPoint.y;
+
+    // get the area inside our border but not our debug margins.
+    nsRect insideBorder(aBox->mRect);
+    insideBorder.MoveTo(0,0):
+    nsMargin border(0,0,0,0);
+    aBox->GetXULBorderAndPadding(border);
+    insideBorder.Deflate(border);
+
+    bool isHorizontal = IsXULHorizontal();
+
+    if (!insideBorder.Contains(nsPoint(x,y)))
+        return NS_ERROR_FAILURE;
+
+    //printf("%%%%%% inside box %%%%%%%\n");
+
+    int count = 0;
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+
+    nsMargin m;
+    nsMargin m2;
+    GetDebugBorder(m);
+    PixelMarginToTwips(m);
+
+    GetDebugMargin(m2);
+    PixelMarginToTwips(m2);
+
+    m += m2;
+
+    if ((isHorizontal && y < insideBorder.y + m.top) ||
+        (!isHorizontal && x < insideBorder.x + m.left)) {
+        //printf("**** inside debug border *******\n");
+        while (child) 
+        {
+            const nsRect& r = child->mRect;
+
+            // if we are not in the child. But in the spacer above the child.
+            if ((isHorizontal && x >= r.x && x < r.x + r.width) ||
+                (!isHorizontal && y >= r.y && y < r.y + r.height)) {
+                aCursor = NS_STYLE_CURSOR_POINTER;
+                   // found it but we already showed it.
+                    if (mDebugChild == child)
+                        return NS_OK;
+
+                    if (aBox->GetContent()) {
+                      printf("---------------\n");
+                      XULDumpBox(stdout);
+                      printf("\n");
+                    }
+
+                    if (child->GetContent()) {
+                        printf("child #%d: ", count);
+                        child->XULDumpBox(stdout);
+                        printf("\n");
+                    }
+
+                    mDebugChild = child;
+
+                    nsSize prefSizeCSS(NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+                    nsSize minSizeCSS (NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+                    nsSize maxSizeCSS (NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+                    nscoord flexCSS = NS_INTRINSICSIZE;
+
+                    bool widthSet, heightSet;
+                    nsIFrame::AddXULPrefSize(child, prefSizeCSS, widthSet, heightSet);
+                    nsIFrame::AddXULMinSize (state, child, minSizeCSS, widthSet, heightSet);
+                    nsIFrame::AddXULMaxSize (child, maxSizeCSS, widthSet, heightSet);
+                    nsIFrame::AddXULFlex    (child, flexCSS);
+
+                    nsSize prefSize = child->GetXULPrefSize(state);
+                    nsSize minSize = child->GetXULMinSize(state);
+                    nsSize maxSize = child->GetXULMaxSize(state);
+                    nscoord flexSize = child->GetXULFlex();
+                    nscoord ascentSize = child->GetXULBoxAscent(state);
+
+                    char min[100];
+                    char pref[100];
+                    char max[100];
+                    char calc[100];
+                    char flex[100];
+                    char ascent[100];
+                  
+                    nsSize actualSize;
+                    GetFrameSizeWithMargin(child, actualSize);
+                    nsSize actualSizeCSS (NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+
+                    GetValue(aPresContext, minSize,  minSizeCSS, min);
+                    GetValue(aPresContext, prefSize, prefSizeCSS, pref);
+                    GetValue(aPresContext, maxSize,  maxSizeCSS, max);
+                    GetValue(aPresContext, actualSize, actualSizeCSS, calc);
+                    GetValue(aPresContext, flexSize,  flexCSS, flex);
+                    GetValue(aPresContext, ascentSize,  NS_INTRINSICSIZE, ascent);
+
+
+                    printf("min%s, pref%s, max%s, actual%s, flex=%s, ascent=%s\n\n", 
+                        min,
+                        pref,
+                        max,
+                        calc,
+                        flex,
+                        ascent
+                    );
+
+                    return NS_OK;   
+            }
+
+          child = GetNextXULBox(child);
+          count++;
+        }
+    } else {
+    }
+
+    mDebugChild = nullptr;
+
+    return NS_OK;
+}
+
+void
+nsBoxFrame::SetDebugOnChildList(nsBoxLayoutState& aState, nsIFrame* aChild, bool aDebug)
+{
+    nsIFrame* child = nsBox::GetChildXULBox(this);
+     while (child)
+     {
+        child->SetXULDebug(aState, aDebug);
+        child = GetNextXULBox(child);
+     }
+}
+
+nsresult
+nsBoxFrame::GetFrameSizeWithMargin(nsIFrame* aBox, nsSize& aSize)
+{
+  nsRect rect(aBox->GetRect());
+  nsMargin margin(0,0,0,0);
+  aBox->GetXULMargin(margin);
+  rect.Inflate(margin);
+  aSize.width = rect.width;
+  aSize.height = rect.height;
+  return NS_OK;
+}
+#endif
+
+// If you make changes to this function, check its counterparts
+// in nsTextBoxFrame and nsXULLabelFrame
+void
+nsBoxFrame::RegUnregAccessKey(bool aDoReg)
+{
+  MOZ_ASSERT(mContent);
+
+  // only support accesskeys for the following elements
+  if (!mContent->IsAnyOfXULElements(nsGkAtoms::button,
+                                    nsGkAtoms::toolbarbutton,
+                                    nsGkAtoms::checkbox,
+                                    nsGkAtoms::textbox,
+                                    nsGkAtoms::tab,
+                                    nsGkAtoms::radio)) {
+    return;
+  }
+
+  nsAutoString accessKey;
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, accessKey);
+
+  if (accessKey.IsEmpty())
+    return;
+
+  // With a valid PresContext we can get the ESM 
+  // and register the access key
+  EventStateManager* esm = PresContext()->EventStateManager();
+
+  uint32_t key = accessKey.First();
+  if (aDoReg)
+    esm->RegisterAccessKey(mContent, key);
+  else
+    esm->UnregisterAccessKey(mContent, key);
+}
+
+bool
+nsBoxFrame::SupportsOrdinalsInChildren()
+{
+  return true;
+}
+
+// Helper less-than-or-equal function, used in CheckBoxOrder() as a
+// template-parameter for the sorting functions.
+bool
+IsBoxOrdinalLEQ(nsIFrame* aFrame1,
+                nsIFrame* aFrame2)
+{
+  // If we've got a placeholder frame, use its out-of-flow frame's ordinal val.
+  nsIFrame* aRealFrame1 = nsPlaceholderFrame::GetRealFrameFor(aFrame1);
+  nsIFrame* aRealFrame2 = nsPlaceholderFrame::GetRealFrameFor(aFrame2);
+  return aRealFrame1->GetXULOrdinal() <= aRealFrame2->GetXULOrdinal();
+}
+
+void 
+nsBoxFrame::CheckBoxOrder()
+{
+  if (SupportsOrdinalsInChildren() &&
+      !nsIFrame::IsFrameListSorted<IsBoxOrdinalLEQ>(mFrames)) {
+    nsIFrame::SortFrameList<IsBoxOrdinalLEQ>(mFrames);
+  }
+}
+
+nsresult
+nsBoxFrame::LayoutChildAt(nsBoxLayoutState& aState, nsIFrame* aBox, const nsRect& aRect)
+{
+  // get the current rect
+  nsRect oldRect(aBox->GetRect());
+  aBox->SetXULBounds(aState, aRect);
+
+  bool layout = NS_SUBTREE_DIRTY(aBox);
+  
+  if (layout || (oldRect.width != aRect.width || oldRect.height != aRect.height))  {
+    return aBox->XULLayout(aState);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsBoxFrame::XULRelayoutChildAtOrdinal(nsIFrame* aChild)
+{
+  if (!SupportsOrdinalsInChildren())
+    return NS_OK;
+
+  uint32_t ord = aChild->GetXULOrdinal();
+  
+  nsIFrame* child = mFrames.FirstChild();
+  nsIFrame* newPrevSib = nullptr;
+
+  while (child) {
+    if (ord < child->GetXULOrdinal()) {
+      break;
+    }
+
+    if (child != aChild) {
+      newPrevSib = child;
+    }
+
+    child = GetNextXULBox(child);
+  }
+
+  if (aChild->GetPrevSibling() == newPrevSib) {
+    // This box is not moving.
+    return NS_OK;
+  }
+
+  // Take |aChild| out of its old position in the child list.
+  mFrames.RemoveFrame(aChild);
+
+  // Insert it after |newPrevSib| or at the start if it's null.
+  mFrames.InsertFrame(nullptr, newPrevSib, aChild);
+
+  return NS_OK;
+}
+
+/**
+ * This wrapper class lets us redirect mouse hits from descendant frames
+ * of a menu to the menu itself, if they didn't specify 'allowevents'.
+ * 
+ * The wrapper simply turns a hit on a descendant element
+ * into a hit on the menu itself, unless there is an element between the target
+ * and the menu with the "allowevents" attribute.
+ * 
+ * This is used by nsMenuFrame and nsTreeColFrame.
+ * 
+ * Note that turning a hit on a descendant element into nullptr, so events
+ * could fall through to the menu background, might be an appealing simplification
+ * but it would mean slightly strange behaviour in some cases, because grabber
+ * wrappers can be created for many individual lists and items, so the exact
+ * fallthrough behaviour would be complex. E.g. an element with "allowevents"
+ * on top of the Content() list could receive the event even if it was covered
+ * by a PositionedDescenants() element without "allowevents". It is best to
+ * never convert a non-null hit into null.
+ */
+// REVIEW: This is roughly of what nsMenuFrame::GetFrameForPoint used to do.
+// I've made 'allowevents' affect child elements because that seems the only
+// reasonable thing to do.
+class nsDisplayXULEventRedirector : public nsDisplayWrapList {
+public:
+  nsDisplayXULEventRedirector(nsDisplayListBuilder* aBuilder,
+                              nsIFrame* aFrame, nsDisplayItem* aItem,
+                              nsIFrame* aTargetFrame)
+    : nsDisplayWrapList(aBuilder, aFrame, aItem), mTargetFrame(aTargetFrame) {}
+  nsDisplayXULEventRedirector(nsDisplayListBuilder* aBuilder,
+                              nsIFrame* aFrame, nsDisplayList* aList,
+                              nsIFrame* aTargetFrame)
+    : nsDisplayWrapList(aBuilder, aFrame, aList), mTargetFrame(aTargetFrame) {}
+  virtual void HitTest(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
+                       HitTestState* aState,
+                       nsTArray<nsIFrame*> *aOutFrames) override;
+  virtual bool ShouldFlattenAway(nsDisplayListBuilder* aBuilder) override {
+    return false;
+  }
+  NS_DISPLAY_DECL_NAME("XULEventRedirector", TYPE_XUL_EVENT_REDIRECTOR)
+private:
+  nsIFrame* mTargetFrame;
+};
+
+void nsDisplayXULEventRedirector::HitTest(nsDisplayListBuilder* aBuilder,
+    const nsRect& aRect, HitTestState* aState, nsTArray<nsIFrame*> *aOutFrames)
+{
+  nsTArray<nsIFrame*> outFrames;
+  mList.HitTest(aBuilder, aRect, aState, &outFrames);
+
+  bool topMostAdded = false;
+  uint32_t localLength = outFrames.Length();
+
+  for (uint32_t i = 0; i < localLength; i++) {
+
+    for (nsIContent* content = outFrames.ElementAt(i)->GetContent();
+         content && content != mTargetFrame->GetContent();
+         content = content->GetParent()) {
+      if (content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::allowevents,
+                               nsGkAtoms::_true, eCaseMatters)) {
+        // Events are allowed on 'frame', so let it go.
+        aOutFrames->AppendElement(outFrames.ElementAt(i));
+        topMostAdded = true;
+      }
+    }
+
+    // If there was no hit on the topmost frame or its ancestors,
+    // add the target frame itself as the first candidate (see bug 562554).
+    if (!topMostAdded) {
+      topMostAdded = true;
+      aOutFrames->AppendElement(mTargetFrame);
+    }
+  }
+}
+
+class nsXULEventRedirectorWrapper : public nsDisplayWrapper
+{
+public:
+  explicit nsXULEventRedirectorWrapper(nsIFrame* aTargetFrame)
+      : mTargetFrame(aTargetFrame) {}
+  virtual nsDisplayItem* WrapList(nsDisplayListBuilder* aBuilder,
+                                  nsIFrame* aFrame,
+                                  nsDisplayList* aList) override {
+    return new (aBuilder)
+        nsDisplayXULEventRedirector(aBuilder, aFrame, aList, mTargetFrame);
+  }
+  virtual nsDisplayItem* WrapItem(nsDisplayListBuilder* aBuilder,
+                                  nsDisplayItem* aItem) override {
+    return new (aBuilder)
+        nsDisplayXULEventRedirector(aBuilder, aItem->Frame(), aItem,
+                                    mTargetFrame);
+  }
+private:
+  nsIFrame* mTargetFrame;
+};
+
+void
+nsBoxFrame::WrapListsInRedirector(nsDisplayListBuilder*   aBuilder,
+                                  const nsDisplayListSet& aIn,
+                                  const nsDisplayListSet& aOut)
+{
+  nsXULEventRedirectorWrapper wrapper(this);
+  wrapper.WrapLists(aBuilder, this, aIn, aOut);
+}
+
+bool
+nsBoxFrame::GetEventPoint(WidgetGUIEvent* aEvent, nsPoint &aPoint) {
+  LayoutDeviceIntPoint refPoint;
+  bool res = GetEventPoint(aEvent, refPoint);
+  aPoint = nsLayoutUtils::GetEventCoordinatesRelativeTo(
+    aEvent, refPoint, this);
+  return res;
+}
+
+bool
+nsBoxFrame::GetEventPoint(WidgetGUIEvent* aEvent, LayoutDeviceIntPoint& aPoint) {
+  NS_ENSURE_TRUE(aEvent, false);
+
+  WidgetTouchEvent* touchEvent = aEvent->AsTouchEvent();
+  if (touchEvent) {
+    // return false if there is more than one touch on the page, or if
+    // we can't find a touch point
+    if (touchEvent->mTouches.Length() != 1) {
+      return false;
+    }
+
+    dom::Touch* touch = touchEvent->mTouches.SafeElementAt(0);
+    if (!touch) {
+      return false;
+    }
+    aPoint = touch->mRefPoint;
+  } else {
+    aPoint = aEvent->mRefPoint;
+  }
+  return true;
+}
diff --git a/layout/xul/nsBoxFrame.h b/layout/xul/nsBoxFrame.h
new file mode 100644
index 0000000000..ad405222fb
--- /dev/null
+++ b/layout/xul/nsBoxFrame.h
@@ -0,0 +1,257 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+
+  Eric D Vaughan
+  nsBoxFrame is a frame that can lay its children out either vertically or horizontally.
+  It lays them out according to a min max or preferred size.
+ 
+**/
+
+#ifndef nsBoxFrame_h___
+#define nsBoxFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsCOMPtr.h"
+#include "nsContainerFrame.h"
+#include "nsBoxLayout.h"
+
+class nsBoxLayoutState;
+
+namespace mozilla {
+namespace gfx {
+class DrawTarget;
+} // namespace gfx
+} // namespace mozilla
+
+nsIFrame* NS_NewBoxFrame(nsIPresShell* aPresShell,
+                         nsStyleContext* aContext,
+                         bool aIsRoot,
+                         nsBoxLayout* aLayoutManager);
+nsIFrame* NS_NewBoxFrame(nsIPresShell* aPresShell,
+                         nsStyleContext* aContext);
+
+class nsBoxFrame : public nsContainerFrame
+{
+protected:
+  typedef mozilla::gfx::DrawTarget DrawTarget;
+
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+#ifdef DEBUG
+  NS_DECL_QUERYFRAME_TARGET(nsBoxFrame)
+  NS_DECL_QUERYFRAME
+#endif
+
+  friend nsIFrame* NS_NewBoxFrame(nsIPresShell* aPresShell, 
+                                  nsStyleContext* aContext,
+                                  bool aIsRoot,
+                                  nsBoxLayout* aLayoutManager);
+  friend nsIFrame* NS_NewBoxFrame(nsIPresShell* aPresShell,
+                                  nsStyleContext* aContext);
+
+  // gets the rect inside our border and debug border. If you wish to paint inside a box
+  // call this method to get the rect so you don't draw on the debug border or outer border.
+
+  virtual void SetXULLayoutManager(nsBoxLayout* aLayout) override { mLayoutManager = aLayout; }
+  virtual nsBoxLayout* GetXULLayoutManager() override { return mLayoutManager; }
+
+  virtual nsresult XULRelayoutChildAtOrdinal(nsIFrame* aChild) override;
+
+  virtual nsSize GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMaxSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nscoord GetXULFlex() override;
+  virtual nscoord GetXULBoxAscent(nsBoxLayoutState& aBoxLayoutState) override;
+#ifdef DEBUG_LAYOUT
+  virtual nsresult SetXULDebug(nsBoxLayoutState& aBoxLayoutState, bool aDebug) override;
+  virtual nsresult GetXULDebug(bool& aDebug) override;
+#endif
+  virtual Valignment GetXULVAlign() const override { return mValign; }
+  virtual Halignment GetXULHAlign() const override { return mHalign; }
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aBoxLayoutState) override;
+
+  virtual bool ComputesOwnOverflowArea() override { return false; }
+
+  // ----- child and sibling operations ---
+
+  // ----- public methods -------
+  
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+ 
+  virtual nsresult AttributeChanged(int32_t         aNameSpaceID,
+                                    nsIAtom*        aAttribute,
+                                    int32_t         aModType) override;
+
+  virtual void MarkIntrinsicISizesDirty() override;
+  virtual nscoord GetMinISize(nsRenderingContext *aRenderingContext) override;
+  virtual nscoord GetPrefISize(nsRenderingContext *aRenderingContext) override;
+
+  virtual void Reflow(nsPresContext*           aPresContext,
+                      ReflowOutput&     aDesiredSize,
+                      const ReflowInput& aReflowInput,
+                      nsReflowStatus&          aStatus) override;
+
+  virtual void SetInitialChildList(ChildListID  aListID,
+                                   nsFrameList& aChildList) override;
+  virtual void AppendFrames(ChildListID     aListID,
+                            nsFrameList&    aFrameList) override;
+  virtual void InsertFrames(ChildListID     aListID,
+                            nsIFrame*       aPrevFrame,
+                            nsFrameList&    aFrameList) override;
+  virtual void RemoveFrame(ChildListID     aListID,
+                           nsIFrame*       aOldFrame) override;
+
+  virtual nsContainerFrame* GetContentInsertionFrame() override;
+
+  virtual void DidSetStyleContext(nsStyleContext* aOldStyleContext) override;
+
+  virtual nsIAtom* GetType() const override;
+
+  virtual bool IsFrameOfType(uint32_t aFlags) const override
+  {
+    // record that children that are ignorable whitespace should be excluded 
+    // (When content was loaded via the XUL content sink, it's already
+    // been excluded, but we need this for when the XUL namespace is used
+    // in other MIME types or when the XUL CSS display types are used with
+    // non-XUL elements.)
+
+    // This is bogus, but it's what we've always done.
+    // (Given that we're replaced, we need to say we're a replaced element
+    // that contains a block so ReflowInput doesn't tell us to be
+    // NS_INTRINSICSIZE wide.)
+    return nsContainerFrame::IsFrameOfType(aFlags &
+      ~(nsIFrame::eReplaced | nsIFrame::eReplacedContainsBlock | eXULBox |
+        nsIFrame::eExcludesIgnorableWhitespace));
+  }
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override;
+#endif
+
+  virtual void DidReflow(nsPresContext*           aPresContext,
+                         const ReflowInput* aReflowInput,
+                         nsDidReflowStatus        aStatus) override;
+
+  virtual bool HonorPrintBackgroundSettings() override;
+
+  virtual ~nsBoxFrame();
+  
+  explicit nsBoxFrame(nsStyleContext* aContext, bool aIsRoot = false, nsBoxLayout* aLayoutManager = nullptr);
+
+  // virtual so nsStackFrame, nsButtonBoxFrame, nsSliderFrame and nsMenuFrame
+  // can override it
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists);
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+  
+#ifdef DEBUG_LAYOUT
+    virtual void SetDebugOnChildList(nsBoxLayoutState& aState, nsIFrame* aChild, bool aDebug);
+    nsresult DisplayDebugInfoFor(nsIFrame*  aBox, 
+                                 nsPoint& aPoint);
+#endif
+
+  static nsresult LayoutChildAt(nsBoxLayoutState& aState, nsIFrame* aBox, const nsRect& aRect);
+
+  /**
+   * Utility method to redirect events on descendants to this frame.
+   * Supports 'allowevents' attribute on descendant elements to allow those
+   * elements and their descendants to receive events.
+   */
+  void WrapListsInRedirector(nsDisplayListBuilder*   aBuilder,
+                             const nsDisplayListSet& aIn,
+                             const nsDisplayListSet& aOut);
+
+  /**
+   * This defaults to true, but some box frames (nsListBoxBodyFrame for
+   * example) don't support ordinals in their children.
+   */
+  virtual bool SupportsOrdinalsInChildren();
+
+protected:
+#ifdef DEBUG_LAYOUT
+    virtual void GetBoxName(nsAutoString& aName) override;
+    void PaintXULDebugBackground(nsRenderingContext& aRenderingContext,
+                                 nsPoint aPt);
+    void PaintXULDebugOverlay(DrawTarget& aRenderingContext,
+                              nsPoint aPt);
+#endif
+
+    virtual bool GetInitialEqualSize(bool& aEqualSize); 
+    virtual void GetInitialOrientation(bool& aIsHorizontal);
+    virtual void GetInitialDirection(bool& aIsNormal);
+    virtual bool GetInitialHAlignment(Halignment& aHalign); 
+    virtual bool GetInitialVAlignment(Valignment& aValign); 
+    virtual bool GetInitialAutoStretch(bool& aStretch); 
+  
+    virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+    nsSize mPrefSize;
+    nsSize mMinSize;
+    nsSize mMaxSize;
+    nscoord mFlex;
+    nscoord mAscent;
+
+    nsCOMPtr<nsBoxLayout> mLayoutManager;
+
+    // Get the point associated with this event. Returns true if a single valid
+    // point was found. Otherwise false.
+    bool GetEventPoint(mozilla::WidgetGUIEvent* aEvent, nsPoint& aPoint);
+    // Gets the event coordinates relative to the widget offset associated with
+    // this frame. Return true if a single valid point was found.
+    bool GetEventPoint(mozilla::WidgetGUIEvent* aEvent,
+                       mozilla::LayoutDeviceIntPoint& aPoint);
+
+protected:
+    void RegUnregAccessKey(bool aDoReg);
+
+  void CheckBoxOrder();
+
+private: 
+
+#ifdef DEBUG_LAYOUT
+    nsresult SetXULDebug(nsPresContext* aPresContext, bool aDebug);
+    bool GetInitialDebug(bool& aDebug);
+    void GetDebugPref();
+
+    void GetDebugBorder(nsMargin& aInset);
+    void GetDebugPadding(nsMargin& aInset);
+    void GetDebugMargin(nsMargin& aInset);
+
+    nsresult GetFrameSizeWithMargin(nsIFrame* aBox, nsSize& aSize);
+
+    void PixelMarginToTwips(nsMargin& aMarginPixels);
+
+    void GetValue(nsPresContext* aPresContext, const nsSize& a, const nsSize& b, char* value);
+    void GetValue(nsPresContext* aPresContext, int32_t a, int32_t b, char* value);
+    void DrawSpacer(nsPresContext* aPresContext, DrawTarget& aDrawTarget, bool aHorizontal, int32_t flex, nscoord x, nscoord y, nscoord size, nscoord spacerSize);
+    void DrawLine(DrawTarget& aDrawTarget,  bool aHorizontal, nscoord x1, nscoord y1, nscoord x2, nscoord y2);
+    void FillRect(DrawTarget& aDrawTarget,  bool aHorizontal, nscoord x, nscoord y, nscoord width, nscoord height);
+#endif
+    virtual void UpdateMouseThrough();
+
+    void CacheAttributes();
+
+    // instance variables.
+    Halignment mHalign;
+    Valignment mValign;
+
+#ifdef DEBUG_LAYOUT
+    static bool gDebug;
+    static nsIFrame* mDebugChild;
+#endif
+
+}; // class nsBoxFrame
+
+#endif
+
diff --git a/layout/xul/nsBoxLayout.cpp b/layout/xul/nsBoxLayout.cpp
new file mode 100644
index 0000000000..60db32a7a5
--- /dev/null
+++ b/layout/xul/nsBoxLayout.cpp
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsBox.h"
+#include "nsCOMPtr.h"
+#include "nsContainerFrame.h"
+#include "nsBoxLayout.h"
+
+void
+nsBoxLayout::AddBorderAndPadding(nsIFrame* aBox, nsSize& aSize)
+{
+  nsBox::AddBorderAndPadding(aBox, aSize);
+}
+
+void
+nsBoxLayout::AddMargin(nsIFrame* aBox, nsSize& aSize)
+{
+  nsBox::AddMargin(aBox, aSize);
+}
+
+void
+nsBoxLayout::AddMargin(nsSize& aSize, const nsMargin& aMargin)
+{
+  nsBox::AddMargin(aSize, aMargin);
+}
+
+nsSize
+nsBoxLayout::GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  nsSize pref (0, 0);
+  AddBorderAndPadding(aBox, pref);
+
+  return pref;
+}
+
+nsSize
+nsBoxLayout::GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  nsSize minSize (0,0);
+  AddBorderAndPadding(aBox, minSize);
+  return minSize;
+}
+
+nsSize
+nsBoxLayout::GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  //AddBorderAndPadding () never changes maxSize (NS_INTRINSICSIZE)
+  //AddBorderAndPadding(aBox, maxSize);
+  return nsSize (NS_INTRINSICSIZE,NS_INTRINSICSIZE);
+}
+
+
+nscoord
+nsBoxLayout::GetAscent(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  return 0;
+}
+
+NS_IMETHODIMP
+nsBoxLayout::XULLayout(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  return NS_OK;
+}
+
+void
+nsBoxLayout::AddLargestSize(nsSize& aSize, const nsSize& aSize2)
+{
+  if (aSize2.width > aSize.width)
+     aSize.width = aSize2.width;
+
+  if (aSize2.height > aSize.height)
+     aSize.height = aSize2.height;
+}
+
+void
+nsBoxLayout::AddSmallestSize(nsSize& aSize, const nsSize& aSize2)
+{
+  if (aSize2.width < aSize.width)
+     aSize.width = aSize2.width;
+
+  if (aSize2.height < aSize.height)
+     aSize.height = aSize2.height;
+}
+
+NS_IMPL_ISUPPORTS(nsBoxLayout, nsBoxLayout)
diff --git a/layout/xul/nsBoxLayout.h b/layout/xul/nsBoxLayout.h
new file mode 100644
index 0000000000..cb4d77170e
--- /dev/null
+++ b/layout/xul/nsBoxLayout.h
@@ -0,0 +1,65 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsBoxLayout_h___
+#define nsBoxLayout_h___
+
+#include "nsISupports.h"
+#include "nsCoord.h"
+#include "nsFrameList.h"
+
+class nsIFrame;
+class nsBoxLayoutState;
+struct nsSize;
+struct nsMargin;
+
+#define NS_BOX_LAYOUT_IID \
+{ 0x09d522a7, 0x304c, 0x4137, \
+ { 0xaf, 0xc9, 0xe0, 0x80, 0x2e, 0x89, 0xb7, 0xe8 } }
+
+class nsIGridPart;
+
+class nsBoxLayout : public nsISupports {
+
+protected:
+  virtual ~nsBoxLayout() {}
+
+public:
+
+  nsBoxLayout() {}
+
+  NS_DECL_ISUPPORTS
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_BOX_LAYOUT_IID)
+
+  NS_IMETHOD XULLayout(nsIFrame* aBox, nsBoxLayoutState& aState);
+
+  virtual nsSize GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState);
+  virtual nsSize GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState);
+  virtual nsSize GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState);
+  virtual nscoord GetAscent(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState);
+  virtual void ChildrenInserted(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                nsIFrame* aPrevBox,
+                                const nsFrameList::Slice& aNewChildren) {}
+  virtual void ChildrenAppended(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                const nsFrameList::Slice& aNewChildren) {}
+  virtual void ChildrenRemoved(nsIFrame* aBox, nsBoxLayoutState& aState, nsIFrame* aChildList) {}
+  virtual void ChildrenSet(nsIFrame* aBox, nsBoxLayoutState& aState, nsIFrame* aChildList) {}
+  virtual void IntrinsicISizesDirty(nsIFrame* aBox, nsBoxLayoutState& aState) {}
+
+  virtual void AddBorderAndPadding(nsIFrame* aBox, nsSize& aSize);
+  virtual void AddMargin(nsIFrame* aChild, nsSize& aSize);
+  virtual void AddMargin(nsSize& aSize, const nsMargin& aMargin);
+
+  virtual nsIGridPart* AsGridPart() { return nullptr; }
+
+  static void AddLargestSize(nsSize& aSize, const nsSize& aToAdd);
+  static void AddSmallestSize(nsSize& aSize, const nsSize& aToAdd);
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsBoxLayout, NS_BOX_LAYOUT_IID)
+
+#endif
+
diff --git a/layout/xul/nsBoxLayoutState.cpp b/layout/xul/nsBoxLayoutState.cpp
new file mode 100644
index 0000000000..e1219534e0
--- /dev/null
+++ b/layout/xul/nsBoxLayoutState.cpp
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsBoxLayoutState.h"
+
+nsBoxLayoutState::nsBoxLayoutState(nsPresContext* aPresContext,
+                                   nsRenderingContext* aRenderingContext,
+                                   const ReflowInput* aOuterReflowInput,
+                                   uint16_t aReflowDepth)
+  : mPresContext(aPresContext)
+  , mRenderingContext(aRenderingContext)
+  , mOuterReflowInput(aOuterReflowInput)
+  , mLayoutFlags(0)
+  , mReflowDepth(aReflowDepth)
+  , mPaintingDisabled(false)
+{
+  NS_ASSERTION(mPresContext, "PresContext must be non-null");
+}
+
+nsBoxLayoutState::nsBoxLayoutState(const nsBoxLayoutState& aState)
+  : mPresContext(aState.mPresContext)
+  , mRenderingContext(aState.mRenderingContext)
+  , mOuterReflowInput(aState.mOuterReflowInput)
+  , mLayoutFlags(aState.mLayoutFlags)
+  , mReflowDepth(aState.mReflowDepth + 1)
+  , mPaintingDisabled(aState.mPaintingDisabled)
+{
+  NS_ASSERTION(mPresContext, "PresContext must be non-null");
+}
diff --git a/layout/xul/nsBoxLayoutState.h b/layout/xul/nsBoxLayoutState.h
new file mode 100644
index 0000000000..b857ad9c09
--- /dev/null
+++ b/layout/xul/nsBoxLayoutState.h
@@ -0,0 +1,77 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ 
+  Author:
+  Eric D Vaughan
+
+**/
+
+#ifndef nsBoxLayoutState_h___
+#define nsBoxLayoutState_h___
+
+#include "nsCOMPtr.h"
+#include "nsPresContext.h"
+#include "nsIPresShell.h"
+
+class nsRenderingContext;
+namespace mozilla {
+struct ReflowInput;
+} // namespace mozilla
+
+
+class MOZ_STACK_CLASS nsBoxLayoutState
+{
+  using ReflowInput = mozilla::ReflowInput;
+
+public:
+  explicit nsBoxLayoutState(nsPresContext* aPresContext,
+                            nsRenderingContext* aRenderingContext = nullptr,
+                            // see OuterReflowInput() below
+                            const ReflowInput* aOuterReflowInput = nullptr,
+                            uint16_t aReflowDepth = 0);
+  nsBoxLayoutState(const nsBoxLayoutState& aState);
+
+  nsPresContext* PresContext() const { return mPresContext; }
+  nsIPresShell* PresShell() const { return mPresContext->PresShell(); }
+
+  uint32_t LayoutFlags() const { return mLayoutFlags; }
+  void SetLayoutFlags(uint32_t aFlags) { mLayoutFlags = aFlags; }
+
+  // if true no one under us will paint during reflow.
+  void SetPaintingDisabled(bool aDisable) { mPaintingDisabled = aDisable; }
+  bool PaintingDisabled() const { return mPaintingDisabled; }
+
+  // The rendering context may be null for specialized uses of
+  // nsBoxLayoutState and should be null-checked before it is used.
+  // However, passing a null rendering context to the constructor when
+  // doing box layout or intrinsic size calculation will cause bugs.
+  nsRenderingContext* GetRenderingContext() const { return mRenderingContext; }
+
+  struct AutoReflowDepth {
+    explicit AutoReflowDepth(nsBoxLayoutState& aState)
+      : mState(aState) { ++mState.mReflowDepth; }
+    ~AutoReflowDepth() { --mState.mReflowDepth; }
+    nsBoxLayoutState& mState;
+  };
+
+  // The HTML reflow state that lives outside the box-block boundary.
+  // May not be set reliably yet.
+  const ReflowInput* OuterReflowInput() { return mOuterReflowInput; }
+
+  uint16_t GetReflowDepth() { return mReflowDepth; }
+  
+private:
+  RefPtr<nsPresContext> mPresContext;
+  nsRenderingContext *mRenderingContext;
+  const ReflowInput *mOuterReflowInput;
+  uint32_t mLayoutFlags;
+  uint16_t mReflowDepth; 
+  bool mPaintingDisabled;
+};
+
+#endif
+
diff --git a/layout/xul/nsButtonBoxFrame.cpp b/layout/xul/nsButtonBoxFrame.cpp
new file mode 100644
index 0000000000..45d9345168
--- /dev/null
+++ b/layout/xul/nsButtonBoxFrame.cpp
@@ -0,0 +1,230 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "nsCOMPtr.h"
+#include "nsButtonBoxFrame.h"
+#include "nsIContent.h"
+#include "nsIDOMNodeList.h"
+#include "nsIDOMXULButtonElement.h"
+#include "nsGkAtoms.h"
+#include "nsNameSpaceManager.h"
+#include "nsPresContext.h"
+#include "nsIPresShell.h"
+#include "nsIDOMElement.h"
+#include "nsDisplayList.h"
+#include "nsContentUtils.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/EventStateManager.h"
+#include "mozilla/EventStates.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/TextEvents.h"
+
+using namespace mozilla;
+
+
+NS_IMPL_ISUPPORTS(nsButtonBoxFrame::nsButtonBoxListener, nsIDOMEventListener)
+
+nsresult
+nsButtonBoxFrame::nsButtonBoxListener::HandleEvent(nsIDOMEvent* aEvent)
+{
+  if (!mButtonBoxFrame) {
+    return NS_OK;
+  }
+
+  nsAutoString eventType;
+  aEvent->GetType(eventType);
+
+  if (eventType.EqualsLiteral("blur")) {
+    mButtonBoxFrame->Blurred();
+    return NS_OK;
+  }
+
+  NS_ABORT();
+
+  return NS_OK;
+}
+
+//
+// NS_NewXULButtonFrame
+//
+// Creates a new Button frame and returns it
+//
+nsIFrame*
+NS_NewButtonBoxFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsButtonBoxFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsButtonBoxFrame)
+
+nsButtonBoxFrame::nsButtonBoxFrame(nsStyleContext* aContext) :
+  nsBoxFrame(aContext, false),
+  mButtonBoxListener(nullptr),
+  mIsHandlingKeyEvent(false)
+{
+  UpdateMouseThrough();
+}
+
+void
+nsButtonBoxFrame::Init(nsIContent*       aContent,
+                       nsContainerFrame* aParent,
+                       nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  mButtonBoxListener = new nsButtonBoxListener(this);
+
+  mContent->AddSystemEventListener(NS_LITERAL_STRING("blur"), mButtonBoxListener, false);
+}
+
+void
+nsButtonBoxFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  mContent->RemoveSystemEventListener(NS_LITERAL_STRING("blur"), mButtonBoxListener, false);
+
+  mButtonBoxListener->mButtonBoxFrame = nullptr;
+  mButtonBoxListener = nullptr;
+
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+void
+nsButtonBoxFrame::BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                              const nsRect&           aDirtyRect,
+                                              const nsDisplayListSet& aLists)
+{
+  // override, since we don't want children to get events
+  if (aBuilder->IsForEventDelivery())
+    return;
+  nsBoxFrame::BuildDisplayListForChildren(aBuilder, aDirtyRect, aLists);
+}
+
+nsresult
+nsButtonBoxFrame::HandleEvent(nsPresContext* aPresContext, 
+                              WidgetGUIEvent* aEvent,
+                              nsEventStatus* aEventStatus)
+{
+  NS_ENSURE_ARG_POINTER(aEventStatus);
+  if (nsEventStatus_eConsumeNoDefault == *aEventStatus) {
+    return NS_OK;
+  }
+
+  switch (aEvent->mMessage) {
+    case eKeyDown: {
+      WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
+      if (!keyEvent) {
+        break;
+      }
+      if (NS_VK_SPACE == keyEvent->mKeyCode) {
+        EventStateManager* esm = aPresContext->EventStateManager();
+        // :hover:active state
+        esm->SetContentState(mContent, NS_EVENT_STATE_HOVER);
+        esm->SetContentState(mContent, NS_EVENT_STATE_ACTIVE);
+        mIsHandlingKeyEvent = true;
+      }
+      break;
+    }
+
+// On mac, Return fires the default button, not the focused one.
+#ifndef XP_MACOSX
+    case eKeyPress: {
+      WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
+      if (!keyEvent) {
+        break;
+      }
+      if (NS_VK_RETURN == keyEvent->mKeyCode) {
+        nsCOMPtr<nsIDOMXULButtonElement> buttonEl(do_QueryInterface(mContent));
+        if (buttonEl) {
+          MouseClicked(aEvent);
+          *aEventStatus = nsEventStatus_eConsumeNoDefault;
+        }
+      }
+      break;
+    }
+#endif
+
+    case eKeyUp: {
+      WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
+      if (!keyEvent) {
+        break;
+      }
+      if (NS_VK_SPACE == keyEvent->mKeyCode) {
+        mIsHandlingKeyEvent = false;
+        // only activate on keyup if we're already in the :hover:active state
+        NS_ASSERTION(mContent->IsElement(), "How do we have a non-element?");
+        EventStates buttonState = mContent->AsElement()->State();
+        if (buttonState.HasAllStates(NS_EVENT_STATE_ACTIVE |
+                                     NS_EVENT_STATE_HOVER)) {
+          // return to normal state
+          EventStateManager* esm = aPresContext->EventStateManager();
+          esm->SetContentState(nullptr, NS_EVENT_STATE_ACTIVE);
+          esm->SetContentState(nullptr, NS_EVENT_STATE_HOVER);
+          MouseClicked(aEvent);
+        }
+      }
+      break;
+    }
+
+    case eMouseClick: {
+      WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+      if (mouseEvent->IsLeftClickEvent()) {
+        MouseClicked(mouseEvent);
+      }
+      break;
+    }
+
+    default:
+      break;
+  }
+
+  return nsBoxFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+}
+
+void
+nsButtonBoxFrame::Blurred()
+{
+  NS_ASSERTION(mContent->IsElement(), "How do we have a non-element?");
+  EventStates buttonState = mContent->AsElement()->State();
+  if (mIsHandlingKeyEvent &&
+      buttonState.HasAllStates(NS_EVENT_STATE_ACTIVE |
+                               NS_EVENT_STATE_HOVER)) {
+    // return to normal state
+    EventStateManager* esm = PresContext()->EventStateManager();
+    esm->SetContentState(nullptr, NS_EVENT_STATE_ACTIVE);
+    esm->SetContentState(nullptr, NS_EVENT_STATE_HOVER);
+  }
+  mIsHandlingKeyEvent = false;
+}
+
+void
+nsButtonBoxFrame::DoMouseClick(WidgetGUIEvent* aEvent, bool aTrustEvent)
+{
+  // Don't execute if we're disabled.
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                            nsGkAtoms::_true, eCaseMatters))
+    return;
+
+  // Execute the oncommand event handler.
+  bool isShift = false;
+  bool isControl = false;
+  bool isAlt = false;
+  bool isMeta = false;
+  if(aEvent) {
+    WidgetInputEvent* inputEvent = aEvent->AsInputEvent();
+    isShift = inputEvent->IsShift();
+    isControl = inputEvent->IsControl();
+    isAlt = inputEvent->IsAlt();
+    isMeta = inputEvent->IsMeta();
+  }
+
+  // Have the content handle the event, propagating it according to normal DOM rules.
+  nsCOMPtr<nsIPresShell> shell = PresContext()->GetPresShell();
+  if (shell) {
+    nsContentUtils::DispatchXULCommand(mContent,
+                                       aEvent ?
+                                         aEvent->IsTrusted() : aTrustEvent,
+                                       nullptr, shell,
+                                       isControl, isAlt, isShift, isMeta);
+  }
+}
diff --git a/layout/xul/nsButtonBoxFrame.h b/layout/xul/nsButtonBoxFrame.h
new file mode 100644
index 0000000000..e9bfd99a50
--- /dev/null
+++ b/layout/xul/nsButtonBoxFrame.h
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsButtonBoxFrame_h___
+#define nsButtonBoxFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsIDOMEventListener.h"
+#include "nsBoxFrame.h"
+
+class nsButtonBoxFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewButtonBoxFrame(nsIPresShell* aPresShell);
+
+  explicit nsButtonBoxFrame(nsStyleContext* aContext);
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) override;
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual nsresult HandleEvent(nsPresContext* aPresContext, 
+                               mozilla::WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  virtual void MouseClicked(mozilla::WidgetGUIEvent* aEvent)
+  { DoMouseClick(aEvent, false); }
+
+  void Blurred();
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override {
+    return MakeFrameName(NS_LITERAL_STRING("ButtonBoxFrame"), aResult);
+  }
+#endif
+
+  /**
+   * Our implementation of MouseClicked. 
+   * @param aTrustEvent if true and aEvent as null, then assume the event was trusted
+   */
+  void DoMouseClick(mozilla::WidgetGUIEvent* aEvent, bool aTrustEvent);
+  void UpdateMouseThrough() override { AddStateBits(NS_FRAME_MOUSE_THROUGH_NEVER); }
+
+private:
+  class nsButtonBoxListener final : public nsIDOMEventListener
+  {
+  public:
+    explicit nsButtonBoxListener(nsButtonBoxFrame* aButtonBoxFrame) :
+      mButtonBoxFrame(aButtonBoxFrame)
+      { }
+
+    NS_IMETHOD HandleEvent(nsIDOMEvent* aEvent) override;
+
+    NS_DECL_ISUPPORTS
+
+  private:
+    friend class nsButtonBoxFrame;
+    virtual ~nsButtonBoxListener() { }
+    nsButtonBoxFrame* mButtonBoxFrame;
+  };
+
+  RefPtr<nsButtonBoxListener> mButtonBoxListener;
+  bool mIsHandlingKeyEvent;
+}; // class nsButtonBoxFrame
+
+#endif /* nsButtonBoxFrame_h___ */
diff --git a/layout/xul/nsDeckFrame.cpp b/layout/xul/nsDeckFrame.cpp
new file mode 100644
index 0000000000..b0c0296b2e
--- /dev/null
+++ b/layout/xul/nsDeckFrame.cpp
@@ -0,0 +1,231 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsDeckFrame.h"
+#include "nsStyleContext.h"
+#include "nsPresContext.h"
+#include "nsIContent.h"
+#include "nsCOMPtr.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsHTMLParts.h"
+#include "nsIPresShell.h"
+#include "nsCSSRendering.h"
+#include "nsViewManager.h"
+#include "nsBoxLayoutState.h"
+#include "nsStackLayout.h"
+#include "nsDisplayList.h"
+#include "nsContainerFrame.h"
+#include "nsContentUtils.h"
+
+#ifdef ACCESSIBILITY
+#include "nsAccessibilityService.h"
+#endif
+
+nsIFrame*
+NS_NewDeckFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsDeckFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsDeckFrame)
+
+NS_QUERYFRAME_HEAD(nsDeckFrame)
+  NS_QUERYFRAME_ENTRY(nsDeckFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsBoxFrame)
+
+
+nsDeckFrame::nsDeckFrame(nsStyleContext* aContext)
+  : nsBoxFrame(aContext), mIndex(0)
+{
+  nsCOMPtr<nsBoxLayout> layout;
+  NS_NewStackLayout(layout);
+  SetXULLayoutManager(layout);
+}
+
+nsIAtom*
+nsDeckFrame::GetType() const
+{
+  return nsGkAtoms::deckFrame;
+}
+
+nsresult
+nsDeckFrame::AttributeChanged(int32_t         aNameSpaceID,
+                              nsIAtom*        aAttribute,
+                              int32_t         aModType)
+{
+  nsresult rv = nsBoxFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                             aModType);
+
+
+   // if the index changed hide the old element and make the new element visible
+  if (aAttribute == nsGkAtoms::selectedIndex) {
+    IndexChanged();
+  }
+
+  return rv;
+}
+
+void
+nsDeckFrame::Init(nsIContent*       aContent,
+                  nsContainerFrame* aParent,
+                  nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  mIndex = GetSelectedIndex();
+}
+
+void
+nsDeckFrame::HideBox(nsIFrame* aBox)
+{
+  nsIPresShell::ClearMouseCapture(aBox);
+}
+
+void
+nsDeckFrame::IndexChanged()
+{
+  //did the index change?
+  int32_t index = GetSelectedIndex();
+  if (index == mIndex)
+    return;
+
+  // redraw
+  InvalidateFrame();
+
+  // hide the currently showing box
+  nsIFrame* currentBox = GetSelectedBox();
+  if (currentBox) // only hide if it exists
+    HideBox(currentBox);
+
+  mIndex = index;
+
+#ifdef ACCESSIBILITY
+  nsAccessibilityService* accService = GetAccService();
+  if (accService) {
+    accService->DeckPanelSwitched(PresContext()->GetPresShell(), mContent,
+                                  currentBox, GetSelectedBox());
+  }
+#endif
+}
+
+int32_t
+nsDeckFrame::GetSelectedIndex()
+{
+  // default index is 0
+  int32_t index = 0;
+
+  // get the index attribute
+  nsAutoString value;
+  if (mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::selectedIndex, value))
+  {
+    nsresult error;
+
+    // convert it to an integer
+    index = value.ToInteger(&error);
+  }
+
+  return index;
+}
+
+nsIFrame* 
+nsDeckFrame::GetSelectedBox()
+{
+  return (mIndex >= 0) ? mFrames.FrameAt(mIndex) : nullptr; 
+}
+
+void
+nsDeckFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                              const nsRect&           aDirtyRect,
+                              const nsDisplayListSet& aLists)
+{
+  // if a tab is hidden all its children are too.
+  if (!StyleVisibility()->mVisible)
+    return;
+    
+  nsBoxFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);
+}
+
+void
+nsDeckFrame::RemoveFrame(ChildListID aListID,
+                         nsIFrame* aOldFrame)
+{
+  nsIFrame* currentFrame = GetSelectedBox();
+  if (currentFrame &&
+      aOldFrame &&
+      currentFrame != aOldFrame) {
+    // If the frame we're removing is at an index that's less
+    // than mIndex, that means we're going to be shifting indexes
+    // by 1.
+    //
+    // We attempt to keep the same child displayed by automatically
+    // updating our internal notion of the current index.
+    int32_t removedIndex = mFrames.IndexOf(aOldFrame);
+    MOZ_ASSERT(removedIndex >= 0,
+               "A deck child was removed that was not in mFrames.");
+    if (removedIndex < mIndex) {
+      mIndex--;
+      // This is going to cause us to handle the index change in IndexedChanged,
+      // but since the new index will match mIndex, it's essentially a noop.
+      nsContentUtils::AddScriptRunner(new nsSetAttrRunnable(
+        mContent, nsGkAtoms::selectedIndex, mIndex));
+    }
+  }
+  nsBoxFrame::RemoveFrame(aListID, aOldFrame);
+}
+
+void
+nsDeckFrame::BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                         const nsRect&           aDirtyRect,
+                                         const nsDisplayListSet& aLists)
+{
+  // only paint the selected box
+  nsIFrame* box = GetSelectedBox();
+  if (!box)
+    return;
+
+  // Putting the child in the background list. This is a little weird but
+  // it matches what we were doing before.
+  nsDisplayListSet set(aLists, aLists.BlockBorderBackgrounds());
+  BuildDisplayListForChild(aBuilder, box, aDirtyRect, set);
+}
+
+NS_IMETHODIMP
+nsDeckFrame::DoXULLayout(nsBoxLayoutState& aState)
+{
+  // Make sure we tweak the state so it does not resize our children.
+  // We will do that.
+  uint32_t oldFlags = aState.LayoutFlags();
+  aState.SetLayoutFlags(NS_FRAME_NO_SIZE_VIEW | NS_FRAME_NO_VISIBILITY);
+
+  // do a normal layout
+  nsresult rv = nsBoxFrame::DoXULLayout(aState);
+
+  // run though each child. Hide all but the selected one
+  nsIFrame* box = nsBox::GetChildXULBox(this);
+
+  nscoord count = 0;
+  while (box) 
+  {
+    // make collapsed children not show up
+    if (count != mIndex) 
+      HideBox(box);
+
+    box = GetNextXULBox(box);
+    count++;
+  }
+
+  aState.SetLayoutFlags(oldFlags);
+
+  return rv;
+}
+
diff --git a/layout/xul/nsDeckFrame.h b/layout/xul/nsDeckFrame.h
new file mode 100644
index 0000000000..2c7ae14451
--- /dev/null
+++ b/layout/xul/nsDeckFrame.h
@@ -0,0 +1,77 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+
+  Eric D Vaughan
+  A frame that can have multiple children. Only one child may be displayed at one time. So the
+  can be flipped though like a deck of cards.
+ 
+**/
+
+#ifndef nsDeckFrame_h___
+#define nsDeckFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+class nsDeckFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_QUERYFRAME_TARGET(nsDeckFrame)
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewDeckFrame(nsIPresShell* aPresShell,
+                                   nsStyleContext* aContext);
+
+  virtual nsresult AttributeChanged(int32_t         aNameSpaceID,
+                                    nsIAtom*        aAttribute,
+                                    int32_t         aModType) override;
+
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aState) override;
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+
+  virtual void RemoveFrame(ChildListID aListID,
+                           nsIFrame* aOldFrame) override;
+
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) override;
+                                         
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual nsIAtom* GetType() const override;
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override
+  {
+      return MakeFrameName(NS_LITERAL_STRING("Deck"), aResult);
+  }
+#endif
+
+  explicit nsDeckFrame(nsStyleContext* aContext);
+
+  nsIFrame* GetSelectedBox();
+
+protected:
+
+  void IndexChanged();
+  int32_t GetSelectedIndex();
+  void HideBox(nsIFrame* aBox);
+
+private:
+
+  int32_t mIndex;
+
+}; // class nsDeckFrame
+
+#endif
+
diff --git a/layout/xul/nsDocElementBoxFrame.cpp b/layout/xul/nsDocElementBoxFrame.cpp
new file mode 100644
index 0000000000..4d978617a4
--- /dev/null
+++ b/layout/xul/nsDocElementBoxFrame.cpp
@@ -0,0 +1,148 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "nsHTMLParts.h"
+#include "nsContainerFrame.h"
+#include "nsCSSRendering.h"
+#include "nsIDocument.h"
+#include "nsPageFrame.h"
+#include "nsIDOMEvent.h"
+#include "nsStyleConsts.h"
+#include "nsGkAtoms.h"
+#include "nsIPresShell.h"
+#include "nsBoxFrame.h"
+#include "nsStackLayout.h"
+#include "nsIAnonymousContentCreator.h"
+#include "mozilla/dom/NodeInfo.h"
+#include "nsIServiceManager.h"
+#include "nsNodeInfoManager.h"
+#include "nsContentCreatorFunctions.h"
+#include "nsContentUtils.h"
+#include "nsContentList.h"
+#include "mozilla/dom/Element.h"
+
+//#define DEBUG_REFLOW
+
+using namespace mozilla::dom;
+
+class nsDocElementBoxFrame : public nsBoxFrame,
+                             public nsIAnonymousContentCreator
+{
+public:
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  friend nsIFrame* NS_NewBoxFrame(nsIPresShell* aPresShell,
+                                  nsStyleContext* aContext);
+
+  explicit nsDocElementBoxFrame(nsStyleContext* aContext)
+    :nsBoxFrame(aContext, true) {}
+
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  // nsIAnonymousContentCreator
+  virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) override;
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
+                                        uint32_t aFilter) override;
+
+  virtual bool IsFrameOfType(uint32_t aFlags) const override
+  {
+    // Override nsBoxFrame.
+    if (aFlags & (nsIFrame::eReplacedContainsBlock | nsIFrame::eReplaced))
+      return false;
+    return nsBoxFrame::IsFrameOfType(aFlags);
+  }
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override;
+#endif
+private:
+  nsCOMPtr<Element> mPopupgroupContent;
+  nsCOMPtr<Element> mTooltipContent;
+};
+
+//----------------------------------------------------------------------
+
+nsContainerFrame*
+NS_NewDocElementBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsDocElementBoxFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsDocElementBoxFrame)
+
+void
+nsDocElementBoxFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  nsContentUtils::DestroyAnonymousContent(&mPopupgroupContent);
+  nsContentUtils::DestroyAnonymousContent(&mTooltipContent);
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+nsresult
+nsDocElementBoxFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
+{
+  nsIDocument* doc = mContent->GetComposedDoc();
+  if (!doc) {
+    // The page is currently being torn down.  Why bother.
+    return NS_ERROR_FAILURE;
+  }
+  nsNodeInfoManager *nodeInfoManager = doc->NodeInfoManager();
+
+  // create the top-secret popupgroup node. shhhhh!
+  RefPtr<NodeInfo> nodeInfo;
+  nodeInfo = nodeInfoManager->GetNodeInfo(nsGkAtoms::popupgroup,
+                                          nullptr, kNameSpaceID_XUL,
+                                          nsIDOMNode::ELEMENT_NODE);
+  NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
+
+  nsresult rv = NS_NewXULElement(getter_AddRefs(mPopupgroupContent),
+                                 nodeInfo.forget());
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (!aElements.AppendElement(mPopupgroupContent))
+    return NS_ERROR_OUT_OF_MEMORY;
+
+  // create the top-secret default tooltip node. shhhhh!
+  nodeInfo = nodeInfoManager->GetNodeInfo(nsGkAtoms::tooltip, nullptr,
+                                          kNameSpaceID_XUL,
+                                          nsIDOMNode::ELEMENT_NODE);
+  NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
+
+  rv = NS_NewXULElement(getter_AddRefs(mTooltipContent), nodeInfo.forget());
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  mTooltipContent->SetAttr(kNameSpaceID_None, nsGkAtoms::_default,
+                           NS_LITERAL_STRING("true"), false);
+
+  if (!aElements.AppendElement(mTooltipContent))
+    return NS_ERROR_OUT_OF_MEMORY;
+
+  return NS_OK;
+}
+
+void
+nsDocElementBoxFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
+                                               uint32_t aFilter)
+{
+  if (mPopupgroupContent) {
+    aElements.AppendElement(mPopupgroupContent);
+  }
+
+  if (mTooltipContent) {
+    aElements.AppendElement(mTooltipContent);
+  }
+}
+
+NS_QUERYFRAME_HEAD(nsDocElementBoxFrame)
+  NS_QUERYFRAME_ENTRY(nsIAnonymousContentCreator)
+NS_QUERYFRAME_TAIL_INHERITING(nsBoxFrame)
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+nsDocElementBoxFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("DocElementBox"), aResult);
+}
+#endif
diff --git a/layout/xul/nsGroupBoxFrame.cpp b/layout/xul/nsGroupBoxFrame.cpp
new file mode 100644
index 0000000000..514287a24a
--- /dev/null
+++ b/layout/xul/nsGroupBoxFrame.cpp
@@ -0,0 +1,311 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// YY need to pass isMultiple before create called
+
+#include "nsBoxFrame.h"
+
+#include "mozilla/gfx/2D.h"
+#include "nsCSSRendering.h"
+#include "nsLayoutUtils.h"
+#include "nsRenderingContext.h"
+#include "nsStyleContext.h"
+#include "nsDisplayList.h"
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+using namespace mozilla::image;
+
+class nsGroupBoxFrame : public nsBoxFrame {
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  explicit nsGroupBoxFrame(nsStyleContext* aContext):
+    nsBoxFrame(aContext) {}
+
+  virtual nsresult GetXULBorderAndPadding(nsMargin& aBorderAndPadding) override;
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override {
+    return MakeFrameName(NS_LITERAL_STRING("GroupBoxFrame"), aResult);
+  }
+#endif
+
+  virtual bool HonorPrintBackgroundSettings() override { return false; }
+
+  DrawResult PaintBorder(nsRenderingContext& aRenderingContext,
+                                   nsPoint aPt,
+                                   const nsRect& aDirtyRect);
+  nsRect GetBackgroundRectRelativeToSelf(nscoord* aOutYOffset = nullptr, nsRect* aOutGroupRect = nullptr);
+
+  // make sure we our kids get our orient and align instead of us.
+  // our child box has no content node so it will search for a parent with one.
+  // that will be us.
+  virtual void GetInitialOrientation(bool& aHorizontal) override { aHorizontal = false; }
+  virtual bool GetInitialHAlignment(Halignment& aHalign) override { aHalign = hAlign_Left; return true; } 
+  virtual bool GetInitialVAlignment(Valignment& aValign) override { aValign = vAlign_Top; return true; } 
+  virtual bool GetInitialAutoStretch(bool& aStretch) override { aStretch = true; return true; } 
+
+  nsIFrame* GetCaptionBox(nsRect& aCaptionRect);
+};
+
+/*
+class nsGroupBoxInnerFrame : public nsBoxFrame {
+public:
+
+    nsGroupBoxInnerFrame(nsIPresShell* aShell, nsStyleContext* aContext):
+      nsBoxFrame(aShell, aContext) {}
+
+
+#ifdef DEBUG_FRAME_DUMP
+  NS_IMETHOD GetFrameName(nsString& aResult) const {
+    return MakeFrameName("GroupBoxFrameInner", aResult);
+  }
+#endif
+  
+  // we are always flexible
+  virtual bool GetDefaultFlex(int32_t& aFlex) { aFlex = 1; return true; }
+
+};
+*/
+
+nsIFrame*
+NS_NewGroupBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsGroupBoxFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsGroupBoxFrame)
+
+class nsDisplayXULGroupBorder : public nsDisplayItem {
+public:
+  nsDisplayXULGroupBorder(nsDisplayListBuilder* aBuilder,
+                              nsGroupBoxFrame* aFrame) :
+    nsDisplayItem(aBuilder, aFrame) {
+    MOZ_COUNT_CTOR(nsDisplayXULGroupBorder);
+  }
+#ifdef NS_BUILD_REFCNT_LOGGING
+  virtual ~nsDisplayXULGroupBorder() {
+    MOZ_COUNT_DTOR(nsDisplayXULGroupBorder);
+  }
+#endif
+
+  nsDisplayItemGeometry* AllocateGeometry(nsDisplayListBuilder* aBuilder) override;
+  void ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
+                                 const nsDisplayItemGeometry* aGeometry,
+                                 nsRegion *aInvalidRegion) override;
+  virtual void HitTest(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
+                       HitTestState* aState, nsTArray<nsIFrame*> *aOutFrames) override {
+    aOutFrames->AppendElement(mFrame);
+  }
+  virtual void Paint(nsDisplayListBuilder* aBuilder,
+                     nsRenderingContext* aCtx) override;
+  NS_DISPLAY_DECL_NAME("XULGroupBackground", TYPE_XUL_GROUP_BACKGROUND)
+};
+
+nsDisplayItemGeometry*
+nsDisplayXULGroupBorder::AllocateGeometry(nsDisplayListBuilder* aBuilder)
+{
+  return new nsDisplayItemGenericImageGeometry(this, aBuilder);
+}
+
+void
+nsDisplayXULGroupBorder::ComputeInvalidationRegion(
+  nsDisplayListBuilder* aBuilder,
+  const nsDisplayItemGeometry* aGeometry,
+  nsRegion* aInvalidRegion)
+{
+  auto geometry =
+    static_cast<const nsDisplayItemGenericImageGeometry*>(aGeometry);
+
+  if (aBuilder->ShouldSyncDecodeImages() &&
+      geometry->ShouldInvalidateToSyncDecodeImages()) {
+    bool snap;
+    aInvalidRegion->Or(*aInvalidRegion, GetBounds(aBuilder, &snap));
+  }
+
+  nsDisplayItem::ComputeInvalidationRegion(aBuilder, aGeometry, aInvalidRegion);
+}
+
+void
+nsDisplayXULGroupBorder::Paint(nsDisplayListBuilder* aBuilder,
+                                   nsRenderingContext* aCtx)
+{
+  DrawResult result = static_cast<nsGroupBoxFrame*>(mFrame)
+    ->PaintBorder(*aCtx, ToReferenceFrame(), mVisibleRect);
+
+  nsDisplayItemGenericImageGeometry::UpdateDrawResult(this, result);
+}
+
+void
+nsGroupBoxFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                  const nsRect&           aDirtyRect,
+                                  const nsDisplayListSet& aLists)
+{
+  // Paint our background and border
+  if (IsVisibleForPainting(aBuilder)) {
+    nsDisplayBackgroundImage::AppendBackgroundItemsToTop(
+      aBuilder, this, GetBackgroundRectRelativeToSelf(),
+      aLists.BorderBackground());
+    aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
+      nsDisplayXULGroupBorder(aBuilder, this));
+    
+    DisplayOutline(aBuilder, aLists);
+  }
+
+  BuildDisplayListForChildren(aBuilder, aDirtyRect, aLists);
+}
+
+nsRect
+nsGroupBoxFrame::GetBackgroundRectRelativeToSelf(nscoord* aOutYOffset, nsRect* aOutGroupRect)
+{
+  const nsMargin& border = StyleBorder()->GetComputedBorder();
+
+  nsRect groupRect;
+  nsIFrame* groupBox = GetCaptionBox(groupRect);
+
+  nscoord yoff = 0;
+  if (groupBox) {
+    // If the border is smaller than the legend, move the border down
+    // to be centered on the legend.
+    nsMargin groupMargin;
+    groupBox->StyleMargin()->GetMargin(groupMargin);
+    groupRect.Inflate(groupMargin);
+
+    if (border.top < groupRect.height) {
+      yoff = (groupRect.height - border.top) / 2 + groupRect.y;
+    }
+  }
+
+  if (aOutYOffset) {
+    *aOutYOffset = yoff;
+  }
+  if (aOutGroupRect) {
+    *aOutGroupRect = groupRect;
+  }
+
+  return nsRect(0, yoff, mRect.width, mRect.height - yoff);
+}
+
+DrawResult
+nsGroupBoxFrame::PaintBorder(nsRenderingContext& aRenderingContext,
+    nsPoint aPt, const nsRect& aDirtyRect) {
+
+  DrawTarget* drawTarget = aRenderingContext.GetDrawTarget();
+  gfxContext* gfx = aRenderingContext.ThebesContext();
+
+  Sides skipSides;
+  const nsStyleBorder* borderStyleData = StyleBorder();
+  const nsMargin& border = borderStyleData->GetComputedBorder();
+  nsPresContext* presContext = PresContext();
+
+  nsRect groupRect;
+  nsIFrame* groupBox = GetCaptionBox(groupRect);
+
+  nscoord yoff = 0;
+  nsRect rect = GetBackgroundRectRelativeToSelf(&yoff, &groupRect) + aPt;
+  groupRect += aPt;
+
+  DrawResult result = DrawResult::SUCCESS;
+  if (groupBox) {
+    int32_t appUnitsPerDevPixel = PresContext()->AppUnitsPerDevPixel();
+
+    // we should probably use PaintBorderEdges to do this but for now just use clipping
+    // to achieve the same effect.
+
+    // draw left side
+    nsRect clipRect(rect);
+    clipRect.width = groupRect.x - rect.x;
+    clipRect.height = border.top;
+
+    gfx->Save();
+    gfx->Clip(NSRectToSnappedRect(clipRect, appUnitsPerDevPixel, *drawTarget));
+    result &=
+      nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
+                                  aDirtyRect, rect, mStyleContext,
+                                  PaintBorderFlags::SYNC_DECODE_IMAGES, skipSides);
+    gfx->Restore();
+
+    // draw right side
+    clipRect = rect;
+    clipRect.x = groupRect.XMost();
+    clipRect.width = rect.XMost() - groupRect.XMost();
+    clipRect.height = border.top;
+
+    gfx->Save();
+    gfx->Clip(NSRectToSnappedRect(clipRect, appUnitsPerDevPixel, *drawTarget));
+    result &=
+      nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
+                                  aDirtyRect, rect, mStyleContext,
+                                  PaintBorderFlags::SYNC_DECODE_IMAGES, skipSides);
+    gfx->Restore();
+  
+    // draw bottom
+
+    clipRect = rect;
+    clipRect.y += border.top;
+    clipRect.height = mRect.height - (yoff + border.top);
+  
+    gfx->Save();
+    gfx->Clip(NSRectToSnappedRect(clipRect, appUnitsPerDevPixel, *drawTarget));
+    result &=
+      nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
+                                  aDirtyRect, rect, mStyleContext,
+                                  PaintBorderFlags::SYNC_DECODE_IMAGES, skipSides);
+    gfx->Restore();
+    
+  } else {
+    result &=
+      nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
+                                  aDirtyRect, nsRect(aPt, GetSize()),
+                                  mStyleContext,
+                                  PaintBorderFlags::SYNC_DECODE_IMAGES, skipSides);
+  }
+
+  return result;
+}
+
+nsIFrame*
+nsGroupBoxFrame::GetCaptionBox(nsRect& aCaptionRect)
+{
+    // first child is our grouped area
+    nsIFrame* box = nsBox::GetChildXULBox(this);
+
+    // no area fail.
+    if (!box)
+      return nullptr;
+
+    // get the first child in the grouped area, that is the caption
+    box = nsBox::GetChildXULBox(box);
+
+    // nothing in the area? fail
+    if (!box)
+      return nullptr;
+
+    // now get the caption itself. It is in the caption frame.
+    nsIFrame* child = nsBox::GetChildXULBox(box);
+
+    if (child) {
+       // convert to our coordinates.
+       nsRect parentRect(box->GetRect());
+       aCaptionRect = child->GetRect();
+       aCaptionRect.x += parentRect.x;
+       aCaptionRect.y += parentRect.y;
+    }
+
+    return child;
+}
+
+nsresult
+nsGroupBoxFrame::GetXULBorderAndPadding(nsMargin& aBorderAndPadding)
+{
+  aBorderAndPadding.SizeTo(0,0,0,0);
+  return NS_OK;
+}
+
diff --git a/layout/xul/nsIBoxObject.idl b/layout/xul/nsIBoxObject.idl
new file mode 100644
index 0000000000..64b1a46f80
--- /dev/null
+++ b/layout/xul/nsIBoxObject.idl
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIDOMElement;
+
+[scriptable, uuid(ce572460-b0f2-4650-a9e7-c53a99d3b6ad)]
+interface nsIBoxObject : nsISupports
+{
+  readonly attribute nsIDOMElement element;
+
+  readonly attribute long x;
+  readonly attribute long y;
+  readonly attribute long screenX;
+  readonly attribute long screenY;
+  readonly attribute long width;
+  readonly attribute long height;
+
+  nsISupports getPropertyAsSupports(in wstring propertyName);
+  void setPropertyAsSupports(in wstring propertyName, in nsISupports value);
+  wstring getProperty(in wstring propertyName);
+  void setProperty(in wstring propertyName, in wstring propertyValue);
+  void removeProperty(in wstring propertyName);
+  
+  // for stepping through content in the expanded dom with box-ordinal-group order
+  readonly attribute nsIDOMElement parentBox;
+  readonly attribute nsIDOMElement firstChild;
+  readonly attribute nsIDOMElement lastChild;
+  readonly attribute nsIDOMElement nextSibling;
+  readonly attribute nsIDOMElement previousSibling;
+};
+
+%{C++
+nsresult
+NS_NewBoxObject(nsIBoxObject** aResult);
+
+%}
diff --git a/layout/xul/nsIBrowserBoxObject.idl b/layout/xul/nsIBrowserBoxObject.idl
new file mode 100644
index 0000000000..f3eee9159c
--- /dev/null
+++ b/layout/xul/nsIBrowserBoxObject.idl
@@ -0,0 +1,16 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIContainerBoxObject.idl"
+
+/**
+ * @deprecated Please consider using ContainerBoxObject.
+ */
+
+[uuid(db436f2f-c656-4754-b0fa-99bc353bd63f)]
+interface nsIBrowserBoxObject : nsIContainerBoxObject
+{
+};
+
diff --git a/layout/xul/nsIContainerBoxObject.idl b/layout/xul/nsIContainerBoxObject.idl
new file mode 100644
index 0000000000..f2eab0fbdc
--- /dev/null
+++ b/layout/xul/nsIContainerBoxObject.idl
@@ -0,0 +1,14 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+// DEPRECATED: This file exists for shim purposes only,
+// see ContainerBoxObject.webidl
+
+[uuid(35d4c04b-3bd3-4375-92e2-a818b4b4acb6)]
+interface nsIContainerBoxObject : nsISupports
+{
+};
diff --git a/layout/xul/nsIListBoxObject.idl b/layout/xul/nsIListBoxObject.idl
new file mode 100644
index 0000000000..198f76919a
--- /dev/null
+++ b/layout/xul/nsIListBoxObject.idl
@@ -0,0 +1,19 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+// DEPRECATED: see ListBoxObject.webidl
+
+interface nsIDOMElement;
+
+[uuid(AA9DEF4E-2E59-412d-A6DF-B76F52167795)]
+interface nsIListBoxObject : nsISupports
+{
+  long getRowCount();
+
+  nsIDOMElement getItemAtIndex(in long index);
+  long getIndexOfItem(in nsIDOMElement item);
+};
diff --git a/layout/xul/nsIMenuBoxObject.idl b/layout/xul/nsIMenuBoxObject.idl
new file mode 100644
index 0000000000..63c7811c4d
--- /dev/null
+++ b/layout/xul/nsIMenuBoxObject.idl
@@ -0,0 +1,14 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+// DEPRECATED: This file exists for shim purposes only,
+// see MenuBoxObject.webidl
+
+[uuid(689ebf3d-0184-450a-9bfa-5a26be0e7a8c)]
+interface nsIMenuBoxObject : nsISupports
+{
+};
diff --git a/layout/xul/nsIRootBox.h b/layout/xul/nsIRootBox.h
new file mode 100644
index 0000000000..9311f547ef
--- /dev/null
+++ b/layout/xul/nsIRootBox.h
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+#ifndef nsIRootBox_h___
+#define nsIRootBox_h___
+
+#include "nsQueryFrame.h"
+class nsPopupSetFrame;
+class nsIContent;
+class nsIPresShell;
+
+class nsIRootBox
+{
+public:
+  NS_DECL_QUERYFRAME_TARGET(nsIRootBox)
+
+  virtual nsPopupSetFrame* GetPopupSetFrame() = 0;
+  virtual void SetPopupSetFrame(nsPopupSetFrame* aPopupSet) = 0;
+
+  virtual nsIContent* GetDefaultTooltip() = 0;
+  virtual void SetDefaultTooltip(nsIContent* aTooltip) = 0;
+
+  virtual nsresult AddTooltipSupport(nsIContent* aNode) = 0;
+  virtual nsresult RemoveTooltipSupport(nsIContent* aNode) = 0;
+
+  static nsIRootBox* GetRootBox(nsIPresShell* aShell);
+};
+
+#endif
+
diff --git a/layout/xul/nsIScrollBoxObject.idl b/layout/xul/nsIScrollBoxObject.idl
new file mode 100644
index 0000000000..fc16f61b1f
--- /dev/null
+++ b/layout/xul/nsIScrollBoxObject.idl
@@ -0,0 +1,12 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+
+[uuid(56E2ADA8-4631-11d4-BA11-001083023C1E)]
+interface nsIScrollBoxObject : nsISupports
+{
+};
diff --git a/layout/xul/nsIScrollbarMediator.h b/layout/xul/nsIScrollbarMediator.h
new file mode 100644
index 0000000000..87b82e3d92
--- /dev/null
+++ b/layout/xul/nsIScrollbarMediator.h
@@ -0,0 +1,91 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIScrollbarMediator_h___
+#define nsIScrollbarMediator_h___
+
+#include "nsQueryFrame.h"
+#include "nsCoord.h"
+
+class nsScrollbarFrame;
+class nsIFrame;
+
+class nsIScrollbarMediator : public nsQueryFrame
+{
+public:
+  NS_DECL_QUERYFRAME_TARGET(nsIScrollbarMediator)
+
+  /**
+   * The aScrollbar argument denotes the scrollbar that's firing the notification.
+   * aScrollbar is never null.
+   * aDirection is either -1, 0, or 1.
+   */
+
+  /**
+   * When set to ENABLE_SNAP, additional scrolling will be performed after the
+   * scroll operation to maintain the constraints set by CSS Scroll snapping.
+   * The additional scrolling may include asynchronous smooth scrolls that
+   * continue to animate after the initial scroll position has been set.
+   */
+  enum ScrollSnapMode { DISABLE_SNAP, ENABLE_SNAP };
+
+  /**
+   * One of the following three methods is called when the scrollbar's button is
+   * clicked.
+   * @note These methods might destroy the frame, pres shell, and other objects.
+   */
+  virtual void ScrollByPage(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                            ScrollSnapMode aSnap = DISABLE_SNAP) = 0;
+  virtual void ScrollByWhole(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                            ScrollSnapMode aSnap = DISABLE_SNAP) = 0;
+  virtual void ScrollByLine(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                            ScrollSnapMode aSnap = DISABLE_SNAP) = 0;
+  /**
+   * RepeatButtonScroll is called when the scrollbar's button is held down. When the
+   * button is first clicked the increment is set; RepeatButtonScroll adds this
+   * increment to the current position.
+   * @note This method might destroy the frame, pres shell, and other objects.
+   */
+  virtual void RepeatButtonScroll(nsScrollbarFrame* aScrollbar) = 0;
+  /**
+   * aOldPos and aNewPos are scroll positions.
+   * The scroll positions start with zero at the left edge; implementors that want
+   * zero at the right edge for RTL content will need to adjust accordingly.
+   * (See ScrollFrameHelper::ThumbMoved in nsGfxScrollFrame.cpp.)
+   * @note This method might destroy the frame, pres shell, and other objects.
+   */
+  virtual void ThumbMoved(nsScrollbarFrame* aScrollbar,
+                          nscoord aOldPos,
+                          nscoord aNewPos) = 0;
+  /**
+   * Called when the scroll bar thumb, slider, or any other component is
+   * released.
+   */
+  virtual void ScrollbarReleased(nsScrollbarFrame* aScrollbar) = 0;
+  virtual void VisibilityChanged(bool aVisible) = 0;
+
+  /**
+   * Obtain the frame for the horizontal or vertical scrollbar, or null
+   * if there is no such box.
+   */
+  virtual nsIFrame* GetScrollbarBox(bool aVertical) = 0;
+  /**
+   * Show or hide scrollbars on 2 fingers touch.
+   * Subclasses should call their ScrollbarActivity's corresponding methods.
+   */
+  virtual void ScrollbarActivityStarted() const = 0;
+  virtual void ScrollbarActivityStopped() const = 0;
+
+  virtual bool IsScrollbarOnRight() const = 0;
+
+  /**
+   * Returns true if the mediator is asking the scrollbar to suppress
+   * repainting itself on changes.
+   */
+  virtual bool ShouldSuppressScrollbarRepaints() const = 0;
+};
+
+#endif
+
diff --git a/layout/xul/nsISliderListener.idl b/layout/xul/nsISliderListener.idl
new file mode 100644
index 0000000000..9605782f0d
--- /dev/null
+++ b/layout/xul/nsISliderListener.idl
@@ -0,0 +1,26 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Used for <scale> to listen to slider changes to avoid mutation listeners
+ */
+[scriptable, uuid(e5b3074e-ee18-4538-83b9-2487d90a2a34)]
+interface nsISliderListener : nsISupports
+{
+  /**
+   * Called when the current, minimum or maximum value has been changed to
+   * newValue. The which parameter will either be 'curpos', 'minpos' or 'maxpos'.
+   * If userChanged is true, then the user changed ths slider, otherwise it
+   * was changed via some other means.
+   */
+  void valueChanged(in AString which, in long newValue, in boolean userChanged);
+
+  /**
+   * Called when the user begins or ends dragging the thumb.
+   */
+  void dragStateChanged(in boolean isDragging);
+};
diff --git a/layout/xul/nsImageBoxFrame.cpp b/layout/xul/nsImageBoxFrame.cpp
new file mode 100644
index 0000000000..fd7c7becf5
--- /dev/null
+++ b/layout/xul/nsImageBoxFrame.cpp
@@ -0,0 +1,828 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsImageBoxFrame.h"
+#include "nsGkAtoms.h"
+#include "nsRenderingContext.h"
+#include "nsStyleContext.h"
+#include "nsStyleConsts.h"
+#include "nsStyleUtil.h"
+#include "nsCOMPtr.h"
+#include "nsPresContext.h"
+#include "nsBoxLayoutState.h"
+
+#include "nsHTMLParts.h"
+#include "nsString.h"
+#include "nsLeafFrame.h"
+#include "nsIPresShell.h"
+#include "nsIDocument.h"
+#include "nsImageMap.h"
+#include "nsILinkHandler.h"
+#include "nsIURL.h"
+#include "nsILoadGroup.h"
+#include "nsContainerFrame.h"
+#include "prprf.h"
+#include "nsCSSRendering.h"
+#include "nsIDOMHTMLImageElement.h"
+#include "nsNameSpaceManager.h"
+#include "nsTextFragment.h"
+#include "nsIDOMHTMLMapElement.h"
+#include "nsTransform2D.h"
+#include "nsITheme.h"
+
+#include "nsIServiceManager.h"
+#include "nsIURI.h"
+#include "nsThreadUtils.h"
+#include "nsDisplayList.h"
+#include "ImageLayers.h"
+#include "ImageContainer.h"
+#include "nsIContent.h"
+
+#include "nsContentUtils.h"
+#include "nsSerializationHelper.h"
+
+#include "mozilla/BasicEvents.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/Maybe.h"
+
+#define ONLOAD_CALLED_TOO_EARLY 1
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+using namespace mozilla::image;
+using namespace mozilla::layers;
+
+class nsImageBoxFrameEvent : public Runnable
+{
+public:
+  nsImageBoxFrameEvent(nsIContent *content, EventMessage message)
+    : mContent(content), mMessage(message) {}
+
+  NS_IMETHOD Run() override;
+
+private:
+  nsCOMPtr<nsIContent> mContent;
+  EventMessage mMessage;
+};
+
+NS_IMETHODIMP
+nsImageBoxFrameEvent::Run()
+{
+  nsIPresShell *pres_shell = mContent->OwnerDoc()->GetShell();
+  if (!pres_shell) {
+    return NS_OK;
+  }
+
+  RefPtr<nsPresContext> pres_context = pres_shell->GetPresContext();
+  if (!pres_context) {
+    return NS_OK;
+  }
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  WidgetEvent event(true, mMessage);
+
+  event.mFlags.mBubbles = false;
+  EventDispatcher::Dispatch(mContent, pres_context, &event, nullptr, &status);
+  return NS_OK;
+}
+
+// Fire off an event that'll asynchronously call the image elements
+// onload handler once handled. This is needed since the image library
+// can't decide if it wants to call it's observer methods
+// synchronously or asynchronously. If an image is loaded from the
+// cache the notifications come back synchronously, but if the image
+// is loaded from the netswork the notifications come back
+// asynchronously.
+
+void
+FireImageDOMEvent(nsIContent* aContent, EventMessage aMessage)
+{
+  NS_ASSERTION(aMessage == eLoad || aMessage == eLoadError,
+               "invalid message");
+
+  nsCOMPtr<nsIRunnable> event = new nsImageBoxFrameEvent(aContent, aMessage);
+  if (NS_FAILED(NS_DispatchToCurrentThread(event)))
+    NS_WARNING("failed to dispatch image event");
+}
+
+//
+// NS_NewImageBoxFrame
+//
+// Creates a new image frame and returns it
+//
+nsIFrame*
+NS_NewImageBoxFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsImageBoxFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsImageBoxFrame)
+
+nsresult
+nsImageBoxFrame::AttributeChanged(int32_t aNameSpaceID,
+                                  nsIAtom* aAttribute,
+                                  int32_t aModType)
+{
+  nsresult rv = nsLeafBoxFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                                 aModType);
+
+  if (aAttribute == nsGkAtoms::src) {
+    UpdateImage();
+    PresContext()->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
+  }
+  else if (aAttribute == nsGkAtoms::validate)
+    UpdateLoadFlags();
+
+  return rv;
+}
+
+nsImageBoxFrame::nsImageBoxFrame(nsStyleContext* aContext):
+  nsLeafBoxFrame(aContext),
+  mIntrinsicSize(0,0),
+  mLoadFlags(nsIRequest::LOAD_NORMAL),
+  mRequestRegistered(false),
+  mUseSrcAttr(false),
+  mSuppressStyleCheck(false)
+{
+  MarkIntrinsicISizesDirty();
+}
+
+nsImageBoxFrame::~nsImageBoxFrame()
+{
+}
+
+
+/* virtual */ void
+nsImageBoxFrame::MarkIntrinsicISizesDirty()
+{
+  SizeNeedsRecalc(mImageSize);
+  nsLeafBoxFrame::MarkIntrinsicISizesDirty();
+}
+
+void
+nsImageBoxFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  if (mImageRequest) {
+    nsLayoutUtils::DeregisterImageRequest(PresContext(), mImageRequest,
+                                          &mRequestRegistered);
+
+    // Release image loader first so that it's refcnt can go to zero
+    mImageRequest->CancelAndForgetObserver(NS_ERROR_FAILURE);
+  }
+
+  if (mListener)
+    reinterpret_cast<nsImageBoxListener*>(mListener.get())->SetFrame(nullptr); // set the frame to null so we don't send messages to a dead object.
+
+  nsLeafBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+
+void
+nsImageBoxFrame::Init(nsIContent*       aContent,
+                      nsContainerFrame* aParent,
+                      nsIFrame*         aPrevInFlow)
+{
+  if (!mListener) {
+    RefPtr<nsImageBoxListener> listener = new nsImageBoxListener();
+    listener->SetFrame(this);
+    mListener = listener.forget();
+  }
+
+  mSuppressStyleCheck = true;
+  nsLeafBoxFrame::Init(aContent, aParent, aPrevInFlow);
+  mSuppressStyleCheck = false;
+
+  UpdateLoadFlags();
+  UpdateImage();
+}
+
+void
+nsImageBoxFrame::UpdateImage()
+{
+  nsPresContext* presContext = PresContext();
+
+  RefPtr<imgRequestProxy> oldImageRequest = mImageRequest;
+
+  if (mImageRequest) {
+    nsLayoutUtils::DeregisterImageRequest(presContext, mImageRequest,
+                                          &mRequestRegistered);
+    mImageRequest->CancelAndForgetObserver(NS_ERROR_FAILURE);
+    mImageRequest = nullptr;
+  }
+
+  // get the new image src
+  nsAutoString src;
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::src, src);
+  mUseSrcAttr = !src.IsEmpty();
+  if (mUseSrcAttr) {
+    nsIDocument* doc = mContent->GetComposedDoc();
+    if (doc) {
+      // Use the serialized loadingPrincipal from the image element. Fall back
+      // to mContent's principal (SystemPrincipal) if not available.
+      nsContentPolicyType contentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE;
+      nsCOMPtr<nsIPrincipal> loadingPrincipal = mContent->NodePrincipal();
+      nsAutoString imageLoadingPrincipal;
+      mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::loadingprincipal,
+                        imageLoadingPrincipal);
+      if (!imageLoadingPrincipal.IsEmpty()) {
+        nsCOMPtr<nsISupports> serializedPrincipal;
+        NS_DeserializeObject(NS_ConvertUTF16toUTF8(imageLoadingPrincipal),
+                             getter_AddRefs(serializedPrincipal));
+        loadingPrincipal = do_QueryInterface(serializedPrincipal);
+
+        if (loadingPrincipal) {
+          // Set the content policy type to TYPE_INTERNAL_IMAGE_FAVICON for
+          // indicating it's a favicon loading.
+          contentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON;
+        } else {
+          // Fallback if the deserialization is failed.
+          loadingPrincipal = mContent->NodePrincipal();
+        }
+      }
+
+      nsCOMPtr<nsIURI> baseURI = mContent->GetBaseURI();
+      nsCOMPtr<nsIURI> uri;
+      nsContentUtils::NewURIWithDocumentCharset(getter_AddRefs(uri),
+                                                src,
+                                                doc,
+                                                baseURI);
+      if (uri) {
+        nsresult rv = nsContentUtils::LoadImage(uri, mContent, doc, loadingPrincipal,
+                                                doc->GetDocumentURI(), doc->GetReferrerPolicy(),
+                                                mListener, mLoadFlags,
+                                                EmptyString(), getter_AddRefs(mImageRequest),
+                                                contentPolicyType);
+
+        if (NS_SUCCEEDED(rv) && mImageRequest) {
+          nsLayoutUtils::RegisterImageRequestIfAnimated(presContext,
+                                                        mImageRequest,
+                                                        &mRequestRegistered);
+        }
+      }
+    }
+  } else {
+    // Only get the list-style-image if we aren't being drawn
+    // by a native theme.
+    uint8_t appearance = StyleDisplay()->mAppearance;
+    if (!(appearance && nsBox::gTheme &&
+          nsBox::gTheme->ThemeSupportsWidget(nullptr, this, appearance))) {
+      // get the list-style-image
+      imgRequestProxy *styleRequest = StyleList()->GetListStyleImage();
+      if (styleRequest) {
+        styleRequest->Clone(mListener, getter_AddRefs(mImageRequest));
+      }
+    }
+  }
+
+  if (!mImageRequest) {
+    // We have no image, so size to 0
+    mIntrinsicSize.SizeTo(0, 0);
+  } else {
+    // We don't want discarding or decode-on-draw for xul images.
+    mImageRequest->StartDecoding();
+    mImageRequest->LockImage();
+  }
+
+  // Do this _after_ locking the new image in case they are the same image.
+  if (oldImageRequest) {
+    oldImageRequest->UnlockImage();
+  }
+}
+
+void
+nsImageBoxFrame::UpdateLoadFlags()
+{
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::always, &nsGkAtoms::never, nullptr};
+  switch (mContent->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::validate,
+                                    strings, eCaseMatters)) {
+    case 0:
+      mLoadFlags = nsIRequest::VALIDATE_ALWAYS;
+      break;
+    case 1:
+      mLoadFlags = nsIRequest::VALIDATE_NEVER|nsIRequest::LOAD_FROM_CACHE;
+      break;
+    default:
+      mLoadFlags = nsIRequest::LOAD_NORMAL;
+      break;
+  }
+}
+
+void
+nsImageBoxFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                  const nsRect&           aDirtyRect,
+                                  const nsDisplayListSet& aLists)
+{
+  nsLeafBoxFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);
+
+  if ((0 == mRect.width) || (0 == mRect.height)) {
+    // Do not render when given a zero area. This avoids some useless
+    // scaling work while we wait for our image dimensions to arrive
+    // asynchronously.
+    return;
+  }
+
+  if (!IsVisibleForPainting(aBuilder))
+    return;
+
+  uint32_t clipFlags =
+    nsStyleUtil::ObjectPropsMightCauseOverflow(StylePosition()) ?
+    0 : DisplayListClipState::ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT;
+
+  DisplayListClipState::AutoClipContainingBlockDescendantsToContentBox
+    clip(aBuilder, this, clipFlags);
+
+  nsDisplayList list;
+  list.AppendNewToTop(
+    new (aBuilder) nsDisplayXULImage(aBuilder, this));
+
+  CreateOwnLayerIfNeeded(aBuilder, &list);
+
+  aLists.Content()->AppendToTop(&list);
+}
+
+DrawResult
+nsImageBoxFrame::PaintImage(nsRenderingContext& aRenderingContext,
+                            const nsRect& aDirtyRect, nsPoint aPt,
+                            uint32_t aFlags)
+{
+  nsRect constraintRect;
+  GetXULClientRect(constraintRect);
+
+  constraintRect += aPt;
+
+  if (!mImageRequest) {
+    // This probably means we're drawn by a native theme.
+    return DrawResult::SUCCESS;
+  }
+
+  // don't draw if the image is not dirty
+  // XXX(seth): Can this actually happen anymore?
+  nsRect dirty;
+  if (!dirty.IntersectRect(aDirtyRect, constraintRect)) {
+    return DrawResult::TEMPORARY_ERROR;
+  }
+
+  // Don't draw if the image's size isn't available.
+  uint32_t imgStatus;
+  if (!NS_SUCCEEDED(mImageRequest->GetImageStatus(&imgStatus)) ||
+      !(imgStatus & imgIRequest::STATUS_SIZE_AVAILABLE)) {
+    return DrawResult::NOT_READY;
+  }
+
+  nsCOMPtr<imgIContainer> imgCon;
+  mImageRequest->GetImage(getter_AddRefs(imgCon));
+
+  if (!imgCon) {
+    return DrawResult::NOT_READY;
+  }
+
+  bool hasSubRect = !mUseSrcAttr && (mSubRect.width > 0 || mSubRect.height > 0);
+
+  Maybe<nsPoint> anchorPoint;
+  nsRect dest;
+  if (!mUseSrcAttr) {
+    // Our image (if we have one) is coming from the CSS property
+    // 'list-style-image' (combined with '-moz-image-region'). For now, ignore
+    // 'object-fit' & 'object-position' in this case, and just fill our rect.
+    // XXXdholbert Should we even honor these properties in this case? They only
+    // apply to replaced elements, and I'm not sure we count as a replaced
+    // element when our image data is determined by CSS.
+    dest = constraintRect;
+  } else {
+    // Determine dest rect based on intrinsic size & ratio, along with
+    // 'object-fit' & 'object-position' properties:
+    IntrinsicSize intrinsicSize;
+    nsSize intrinsicRatio;
+    if (mIntrinsicSize.width > 0 && mIntrinsicSize.height > 0) {
+      // Image has a valid size; use it as intrinsic size & ratio.
+      intrinsicSize.width.SetCoordValue(mIntrinsicSize.width);
+      intrinsicSize.height.SetCoordValue(mIntrinsicSize.height);
+      intrinsicRatio = mIntrinsicSize;
+    } else {
+      // Image doesn't have a (valid) intrinsic size.
+      // Try to look up intrinsic ratio and use that at least.
+      imgCon->GetIntrinsicRatio(&intrinsicRatio);
+    }
+    anchorPoint.emplace();
+    dest = nsLayoutUtils::ComputeObjectDestRect(constraintRect,
+                                                intrinsicSize,
+                                                intrinsicRatio,
+                                                StylePosition(),
+                                                anchorPoint.ptr());
+  }
+
+
+  return nsLayoutUtils::DrawSingleImage(
+           *aRenderingContext.ThebesContext(),
+           PresContext(), imgCon,
+           nsLayoutUtils::GetSamplingFilterForFrame(this),
+           dest, dirty, nullptr, aFlags,
+           anchorPoint.ptrOr(nullptr),
+           hasSubRect ? &mSubRect : nullptr);
+}
+
+void nsDisplayXULImage::Paint(nsDisplayListBuilder* aBuilder,
+                              nsRenderingContext* aCtx)
+{
+  uint32_t flags = imgIContainer::FLAG_NONE;
+  if (aBuilder->ShouldSyncDecodeImages())
+    flags |= imgIContainer::FLAG_SYNC_DECODE;
+  if (aBuilder->IsPaintingToWindow())
+    flags |= imgIContainer::FLAG_HIGH_QUALITY_SCALING;
+
+  DrawResult result = static_cast<nsImageBoxFrame*>(mFrame)->
+    PaintImage(*aCtx, mVisibleRect, ToReferenceFrame(), flags);
+
+  nsDisplayItemGenericImageGeometry::UpdateDrawResult(this, result);
+}
+
+nsDisplayItemGeometry*
+nsDisplayXULImage::AllocateGeometry(nsDisplayListBuilder* aBuilder)
+{
+  return new nsDisplayItemGenericImageGeometry(this, aBuilder);
+}
+
+void
+nsDisplayXULImage::ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
+                                             const nsDisplayItemGeometry* aGeometry,
+                                             nsRegion* aInvalidRegion)
+{
+  auto boxFrame = static_cast<nsImageBoxFrame*>(mFrame);
+  auto geometry =
+    static_cast<const nsDisplayItemGenericImageGeometry*>(aGeometry);
+
+  if (aBuilder->ShouldSyncDecodeImages() &&
+      boxFrame->mImageRequest &&
+      geometry->ShouldInvalidateToSyncDecodeImages()) {
+      bool snap;
+      aInvalidRegion->Or(*aInvalidRegion, GetBounds(aBuilder, &snap));
+  }
+
+  nsDisplayImageContainer::ComputeInvalidationRegion(aBuilder, aGeometry, aInvalidRegion);
+}
+
+bool
+nsDisplayXULImage::CanOptimizeToImageLayer(LayerManager* aManager,
+                                           nsDisplayListBuilder* aBuilder)
+{
+  nsImageBoxFrame* imageFrame = static_cast<nsImageBoxFrame*>(mFrame);
+  if (!imageFrame->CanOptimizeToImageLayer()) {
+    return false;
+  }
+
+  return nsDisplayImageContainer::CanOptimizeToImageLayer(aManager, aBuilder);
+}
+
+already_AddRefed<imgIContainer>
+nsDisplayXULImage::GetImage()
+{
+  nsImageBoxFrame* imageFrame = static_cast<nsImageBoxFrame*>(mFrame);
+  if (!imageFrame->mImageRequest) {
+    return nullptr;
+  }
+
+  nsCOMPtr<imgIContainer> imgCon;
+  imageFrame->mImageRequest->GetImage(getter_AddRefs(imgCon));
+  
+  return imgCon.forget();
+}
+
+nsRect
+nsDisplayXULImage::GetDestRect()
+{
+  nsImageBoxFrame* imageFrame = static_cast<nsImageBoxFrame*>(mFrame);
+
+  nsRect clientRect;
+  imageFrame->GetXULClientRect(clientRect);
+
+  return clientRect + ToReferenceFrame();
+}
+
+bool
+nsImageBoxFrame::CanOptimizeToImageLayer()
+{
+  bool hasSubRect = !mUseSrcAttr && (mSubRect.width > 0 || mSubRect.height > 0);
+  if (hasSubRect) {
+    return false;
+  }
+  return true;
+}
+
+//
+// DidSetStyleContext
+//
+// When the style context changes, make sure that all of our image is up to date.
+//
+/* virtual */ void
+nsImageBoxFrame::DidSetStyleContext(nsStyleContext* aOldStyleContext)
+{
+  nsLeafBoxFrame::DidSetStyleContext(aOldStyleContext);
+
+  // Fetch our subrect.
+  const nsStyleList* myList = StyleList();
+  mSubRect = myList->mImageRegion; // before |mSuppressStyleCheck| test!
+
+  if (mUseSrcAttr || mSuppressStyleCheck)
+    return; // No more work required, since the image isn't specified by style.
+
+  // If we're using a native theme implementation, we shouldn't draw anything.
+  const nsStyleDisplay* disp = StyleDisplay();
+  if (disp->mAppearance && nsBox::gTheme &&
+      nsBox::gTheme->ThemeSupportsWidget(nullptr, this, disp->mAppearance))
+    return;
+
+  // If list-style-image changes, we have a new image.
+  nsCOMPtr<nsIURI> oldURI, newURI;
+  if (mImageRequest)
+    mImageRequest->GetURI(getter_AddRefs(oldURI));
+  if (myList->GetListStyleImage())
+    myList->GetListStyleImage()->GetURI(getter_AddRefs(newURI));
+  bool equal;
+  if (newURI == oldURI ||   // handles null==null
+      (newURI && oldURI &&
+       NS_SUCCEEDED(newURI->Equals(oldURI, &equal)) && equal))
+    return;
+
+  UpdateImage();
+} // DidSetStyleContext
+
+void
+nsImageBoxFrame::GetImageSize()
+{
+  if (mIntrinsicSize.width > 0 && mIntrinsicSize.height > 0) {
+    mImageSize.width = mIntrinsicSize.width;
+    mImageSize.height = mIntrinsicSize.height;
+  } else {
+    mImageSize.width = 0;
+    mImageSize.height = 0;
+  }
+}
+
+/**
+ * Ok return our dimensions
+ */
+nsSize
+nsImageBoxFrame::GetXULPrefSize(nsBoxLayoutState& aState)
+{
+  nsSize size(0,0);
+  DISPLAY_PREF_SIZE(this, size);
+  if (DoesNeedRecalc(mImageSize))
+     GetImageSize();
+
+  if (!mUseSrcAttr && (mSubRect.width > 0 || mSubRect.height > 0))
+    size = mSubRect.Size();
+  else
+    size = mImageSize;
+
+  nsSize intrinsicSize = size;
+
+  nsMargin borderPadding(0,0,0,0);
+  GetXULBorderAndPadding(borderPadding);
+  size.width += borderPadding.LeftRight();
+  size.height += borderPadding.TopBottom();
+
+  bool widthSet, heightSet;
+  nsIFrame::AddXULPrefSize(this, size, widthSet, heightSet);
+  NS_ASSERTION(size.width != NS_INTRINSICSIZE && size.height != NS_INTRINSICSIZE,
+               "non-intrinsic size expected");
+
+  nsSize minSize = GetXULMinSize(aState);
+  nsSize maxSize = GetXULMaxSize(aState);
+
+  if (!widthSet && !heightSet) {
+    if (minSize.width != NS_INTRINSICSIZE)
+      minSize.width -= borderPadding.LeftRight();
+    if (minSize.height != NS_INTRINSICSIZE)
+      minSize.height -= borderPadding.TopBottom();
+    if (maxSize.width != NS_INTRINSICSIZE)
+      maxSize.width -= borderPadding.LeftRight();
+    if (maxSize.height != NS_INTRINSICSIZE)
+      maxSize.height -= borderPadding.TopBottom();
+
+    size = nsLayoutUtils::ComputeAutoSizeWithIntrinsicDimensions(minSize.width, minSize.height,
+                                                                 maxSize.width, maxSize.height,
+                                                                 intrinsicSize.width, intrinsicSize.height);
+    NS_ASSERTION(size.width != NS_INTRINSICSIZE && size.height != NS_INTRINSICSIZE,
+                 "non-intrinsic size expected");
+    size.width += borderPadding.LeftRight();
+    size.height += borderPadding.TopBottom();
+    return size;
+  }
+
+  if (!widthSet) {
+    if (intrinsicSize.height > 0) {
+      // Subtract off the border and padding from the height because the
+      // content-box needs to be used to determine the ratio
+      nscoord height = size.height - borderPadding.TopBottom();
+      size.width = nscoord(int64_t(height) * int64_t(intrinsicSize.width) /
+                           int64_t(intrinsicSize.height));
+    }
+    else {
+      size.width = intrinsicSize.width;
+    }
+
+    size.width += borderPadding.LeftRight();
+  }
+  else if (!heightSet) {
+    if (intrinsicSize.width > 0) {
+      nscoord width = size.width - borderPadding.LeftRight();
+      size.height = nscoord(int64_t(width) * int64_t(intrinsicSize.height) /
+                            int64_t(intrinsicSize.width));
+    }
+    else {
+      size.height = intrinsicSize.height;
+    }
+
+    size.height += borderPadding.TopBottom();
+  }
+
+  return BoundsCheck(minSize, size, maxSize);
+}
+
+nsSize
+nsImageBoxFrame::GetXULMinSize(nsBoxLayoutState& aState)
+{
+  // An image can always scale down to (0,0).
+  nsSize size(0,0);
+  DISPLAY_MIN_SIZE(this, size);
+  AddBorderAndPadding(size);
+  bool widthSet, heightSet;
+  nsIFrame::AddXULMinSize(aState, this, size, widthSet, heightSet);
+  return size;
+}
+
+nscoord
+nsImageBoxFrame::GetXULBoxAscent(nsBoxLayoutState& aState)
+{
+  return GetXULPrefSize(aState).height;
+}
+
+nsIAtom*
+nsImageBoxFrame::GetType() const
+{
+  return nsGkAtoms::imageBoxFrame;
+}
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+nsImageBoxFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("ImageBox"), aResult);
+}
+#endif
+
+nsresult
+nsImageBoxFrame::Notify(imgIRequest* aRequest,
+                        int32_t aType,
+                        const nsIntRect* aData)
+{
+  if (aType == imgINotificationObserver::SIZE_AVAILABLE) {
+    nsCOMPtr<imgIContainer> image;
+    aRequest->GetImage(getter_AddRefs(image));
+    return OnSizeAvailable(aRequest, image);
+  }
+
+  if (aType == imgINotificationObserver::DECODE_COMPLETE) {
+    return OnDecodeComplete(aRequest);
+  }
+
+  if (aType == imgINotificationObserver::LOAD_COMPLETE) {
+    uint32_t imgStatus;
+    aRequest->GetImageStatus(&imgStatus);
+    nsresult status =
+        imgStatus & imgIRequest::STATUS_ERROR ? NS_ERROR_FAILURE : NS_OK;
+    return OnLoadComplete(aRequest, status);
+  }
+
+  if (aType == imgINotificationObserver::IS_ANIMATED) {
+    return OnImageIsAnimated(aRequest);
+  }
+
+  if (aType == imgINotificationObserver::FRAME_UPDATE) {
+    return OnFrameUpdate(aRequest);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsImageBoxFrame::OnSizeAvailable(imgIRequest* aRequest, imgIContainer* aImage)
+{
+  NS_ENSURE_ARG_POINTER(aImage);
+
+  // Ensure the animation (if any) is started. Note: There is no
+  // corresponding call to Decrement for this. This Increment will be
+  // 'cleaned up' by the Request when it is destroyed, but only then.
+  aRequest->IncrementAnimationConsumers();
+
+  nscoord w, h;
+  aImage->GetWidth(&w);
+  aImage->GetHeight(&h);
+
+  mIntrinsicSize.SizeTo(nsPresContext::CSSPixelsToAppUnits(w),
+                        nsPresContext::CSSPixelsToAppUnits(h));
+
+  if (!(GetStateBits() & NS_FRAME_FIRST_REFLOW)) {
+    PresContext()->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsImageBoxFrame::OnDecodeComplete(imgIRequest* aRequest)
+{
+  nsBoxLayoutState state(PresContext());
+  this->XULRedraw(state);
+  return NS_OK;
+}
+
+nsresult
+nsImageBoxFrame::OnLoadComplete(imgIRequest* aRequest, nsresult aStatus)
+{
+  if (NS_SUCCEEDED(aStatus)) {
+    // Fire an onload DOM event.
+    FireImageDOMEvent(mContent, eLoad);
+  } else {
+    // Fire an onerror DOM event.
+    mIntrinsicSize.SizeTo(0, 0);
+    PresContext()->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
+    FireImageDOMEvent(mContent, eLoadError);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsImageBoxFrame::OnImageIsAnimated(imgIRequest* aRequest)
+{
+  // Register with our refresh driver, if we're animated.
+  nsLayoutUtils::RegisterImageRequest(PresContext(), aRequest,
+                                      &mRequestRegistered);
+
+  return NS_OK;
+}
+
+nsresult
+nsImageBoxFrame::OnFrameUpdate(imgIRequest* aRequest)
+{
+  if ((0 == mRect.width) || (0 == mRect.height)) {
+    return NS_OK;
+  }
+ 
+  InvalidateLayer(nsDisplayItem::TYPE_XUL_IMAGE);
+
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(nsImageBoxListener, imgINotificationObserver, imgIOnloadBlocker)
+
+nsImageBoxListener::nsImageBoxListener()
+{
+}
+
+nsImageBoxListener::~nsImageBoxListener()
+{
+}
+
+NS_IMETHODIMP
+nsImageBoxListener::Notify(imgIRequest *request, int32_t aType, const nsIntRect* aData)
+{
+  if (!mFrame)
+    return NS_OK;
+
+  return mFrame->Notify(request, aType, aData);
+}
+
+NS_IMETHODIMP
+nsImageBoxListener::BlockOnload(imgIRequest *aRequest)
+{
+  if (mFrame && mFrame->GetContent() && mFrame->GetContent()->GetUncomposedDoc()) {
+    mFrame->GetContent()->GetUncomposedDoc()->BlockOnload();
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsImageBoxListener::UnblockOnload(imgIRequest *aRequest)
+{
+  if (mFrame && mFrame->GetContent() && mFrame->GetContent()->GetUncomposedDoc()) {
+    mFrame->GetContent()->GetUncomposedDoc()->UnblockOnload(false);
+  }
+
+  return NS_OK;
+}
diff --git a/layout/xul/nsImageBoxFrame.h b/layout/xul/nsImageBoxFrame.h
new file mode 100644
index 0000000000..7faccccaee
--- /dev/null
+++ b/layout/xul/nsImageBoxFrame.h
@@ -0,0 +1,163 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsImageBoxFrame_h___
+#define nsImageBoxFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsLeafBoxFrame.h"
+
+#include "imgILoader.h"
+#include "imgIRequest.h"
+#include "imgIContainer.h"
+#include "imgINotificationObserver.h"
+#include "imgIOnloadBlocker.h"
+
+class imgRequestProxy;
+class nsImageBoxFrame;
+
+class nsDisplayXULImage;
+
+class nsImageBoxListener final : public imgINotificationObserver,
+                                 public imgIOnloadBlocker
+{
+public:
+  nsImageBoxListener();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_IMGINOTIFICATIONOBSERVER
+  NS_DECL_IMGIONLOADBLOCKER
+
+  void SetFrame(nsImageBoxFrame *frame) { mFrame = frame; }
+
+private:
+  virtual ~nsImageBoxListener();
+
+  nsImageBoxFrame *mFrame;
+};
+
+class nsImageBoxFrame final : public nsLeafBoxFrame
+{
+public:
+  typedef mozilla::image::DrawResult DrawResult;
+  typedef mozilla::layers::ImageContainer ImageContainer;
+  typedef mozilla::layers::LayerManager LayerManager;
+
+  friend class nsDisplayXULImage;
+  NS_DECL_FRAMEARENA_HELPERS
+
+  virtual nsSize GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nscoord GetXULBoxAscent(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual void MarkIntrinsicISizesDirty() override;
+
+  nsresult Notify(imgIRequest *aRequest, int32_t aType, const nsIntRect* aData);
+
+  friend nsIFrame* NS_NewImageBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         asPrevInFlow) override;
+
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+  virtual void DidSetStyleContext(nsStyleContext* aOldStyleContext) override;
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual nsIAtom* GetType() const override;
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override;
+#endif
+
+  /** 
+   * Update mUseSrcAttr from appropriate content attributes or from
+   * style, throw away the current image, and load the appropriate
+   * image.
+   * */
+  void UpdateImage();
+
+  /**
+   * Update mLoadFlags from content attributes. Does not attempt to reload the
+   * image using the new load flags.
+   */
+  void UpdateLoadFlags();
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+
+  virtual ~nsImageBoxFrame();
+
+  DrawResult PaintImage(nsRenderingContext& aRenderingContext,
+                        const nsRect& aDirtyRect,
+                        nsPoint aPt, uint32_t aFlags);
+
+  bool CanOptimizeToImageLayer();
+
+protected:
+  explicit nsImageBoxFrame(nsStyleContext* aContext);
+
+  virtual void GetImageSize();
+
+private:
+  nsresult OnSizeAvailable(imgIRequest* aRequest, imgIContainer* aImage);
+  nsresult OnDecodeComplete(imgIRequest* aRequest);
+  nsresult OnLoadComplete(imgIRequest* aRequest, nsresult aStatus);
+  nsresult OnImageIsAnimated(imgIRequest* aRequest);
+  nsresult OnFrameUpdate(imgIRequest* aRequest);
+
+  nsRect mSubRect; ///< If set, indicates that only the portion of the image specified by the rect should be used.
+  nsSize mIntrinsicSize;
+  nsSize mImageSize;
+
+  RefPtr<imgRequestProxy> mImageRequest;
+  nsCOMPtr<imgINotificationObserver> mListener;
+
+  int32_t mLoadFlags;
+
+  // Boolean variable to determine if the current image request has been
+  // registered with the refresh driver.
+  bool mRequestRegistered;
+
+  bool mUseSrcAttr; ///< Whether or not the image src comes from an attribute.
+  bool mSuppressStyleCheck;
+}; // class nsImageBoxFrame
+
+class nsDisplayXULImage : public nsDisplayImageContainer {
+public:
+  nsDisplayXULImage(nsDisplayListBuilder* aBuilder,
+                    nsImageBoxFrame* aFrame) :
+    nsDisplayImageContainer(aBuilder, aFrame) {
+    MOZ_COUNT_CTOR(nsDisplayXULImage);
+  }
+#ifdef NS_BUILD_REFCNT_LOGGING
+  virtual ~nsDisplayXULImage() {
+    MOZ_COUNT_DTOR(nsDisplayXULImage);
+  }
+#endif
+
+  virtual bool CanOptimizeToImageLayer(LayerManager* aManager,
+                                       nsDisplayListBuilder* aBuilder) override;
+  virtual already_AddRefed<imgIContainer> GetImage() override;
+  virtual nsRect GetDestRect() override;
+  virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder, bool* aSnap) override
+  {
+    *aSnap = true;
+    return nsRect(ToReferenceFrame(), Frame()->GetSize());
+  }
+  virtual nsDisplayItemGeometry* AllocateGeometry(nsDisplayListBuilder* aBuilder) override;
+  virtual void ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
+                                         const nsDisplayItemGeometry* aGeometry,
+                                         nsRegion* aInvalidRegion) override;
+  // Doesn't handle HitTest because nsLeafBoxFrame already creates an
+  // event receiver for us
+  virtual void Paint(nsDisplayListBuilder* aBuilder,
+                     nsRenderingContext* aCtx) override;
+  NS_DISPLAY_DECL_NAME("XULImage", TYPE_XUL_IMAGE)
+};
+
+#endif /* nsImageBoxFrame_h___ */
diff --git a/layout/xul/nsLeafBoxFrame.cpp b/layout/xul/nsLeafBoxFrame.cpp
new file mode 100644
index 0000000000..6d1783c11c
--- /dev/null
+++ b/layout/xul/nsLeafBoxFrame.cpp
@@ -0,0 +1,390 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsLeafBoxFrame.h"
+#include "nsBoxFrame.h"
+#include "nsCOMPtr.h"
+#include "nsGkAtoms.h"
+#include "nsPresContext.h"
+#include "nsStyleContext.h"
+#include "nsIContent.h"
+#include "nsNameSpaceManager.h"
+#include "nsBoxLayoutState.h"
+#include "nsWidgetsCID.h"
+#include "nsViewManager.h"
+#include "nsContainerFrame.h"
+#include "nsDisplayList.h"
+#include <algorithm>
+
+using namespace mozilla;
+
+//
+// NS_NewLeafBoxFrame
+//
+// Creates a new Toolbar frame and returns it
+//
+nsIFrame*
+NS_NewLeafBoxFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsLeafBoxFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsLeafBoxFrame)
+
+nsLeafBoxFrame::nsLeafBoxFrame(nsStyleContext* aContext)
+    : nsLeafFrame(aContext)
+{
+}
+
+#ifdef DEBUG_LAYOUT
+void
+nsLeafBoxFrame::GetBoxName(nsAutoString& aName)
+{
+   GetFrameName(aName);
+}
+#endif
+
+
+/**
+ * Initialize us. This is a good time to get the alignment of the box
+ */
+void
+nsLeafBoxFrame::Init(nsIContent*       aContent,
+                     nsContainerFrame* aParent,
+                     nsIFrame*         aPrevInFlow)
+{
+  nsLeafFrame::Init(aContent, aParent, aPrevInFlow);
+
+  if (GetStateBits() & NS_FRAME_FONT_INFLATION_CONTAINER) {
+    AddStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT);
+  }
+
+  UpdateMouseThrough();
+}
+
+nsresult
+nsLeafBoxFrame::AttributeChanged(int32_t aNameSpaceID,
+                                 nsIAtom* aAttribute,
+                                 int32_t aModType)
+{
+  nsresult rv = nsLeafFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                              aModType);
+
+  if (aAttribute == nsGkAtoms::mousethrough) 
+    UpdateMouseThrough();
+
+  return rv;
+}
+
+void nsLeafBoxFrame::UpdateMouseThrough()
+{
+  if (mContent) {
+    static nsIContent::AttrValuesArray strings[] =
+      {&nsGkAtoms::never, &nsGkAtoms::always, nullptr};
+    switch (mContent->FindAttrValueIn(kNameSpaceID_None,
+                                      nsGkAtoms::mousethrough,
+                                      strings, eCaseMatters)) {
+      case 0: AddStateBits(NS_FRAME_MOUSE_THROUGH_NEVER); break;
+      case 1: AddStateBits(NS_FRAME_MOUSE_THROUGH_ALWAYS); break;
+      case 2: {
+          RemoveStateBits(NS_FRAME_MOUSE_THROUGH_ALWAYS);
+          RemoveStateBits(NS_FRAME_MOUSE_THROUGH_NEVER);
+          break;
+      }
+    }
+  }
+}
+
+void
+nsLeafBoxFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                 const nsRect&           aDirtyRect,
+                                 const nsDisplayListSet& aLists)
+{
+  // REVIEW: GetFrameForPoint used to not report events for the background
+  // layer, whereas this code will put an event receiver for this frame in the
+  // BlockBorderBackground() list. But I don't see any need to preserve
+  // that anomalous behaviour. The important thing I'm preserving is that
+  // leaf boxes continue to receive events in the foreground layer.
+  DisplayBorderBackgroundOutline(aBuilder, aLists);
+
+  if (!aBuilder->IsForEventDelivery() || !IsVisibleForPainting(aBuilder))
+    return;
+
+  aLists.Content()->AppendNewToTop(new (aBuilder)
+    nsDisplayEventReceiver(aBuilder, this));
+}
+
+/* virtual */ nscoord
+nsLeafBoxFrame::GetMinISize(nsRenderingContext *aRenderingContext)
+{
+  nscoord result;
+  DISPLAY_MIN_WIDTH(this, result);
+  nsBoxLayoutState state(PresContext(), aRenderingContext);
+
+  WritingMode wm = GetWritingMode();
+  LogicalSize minSize(wm, GetXULMinSize(state));
+
+  // GetXULMinSize returns border-box size, and we want to return content
+  // inline-size.  Since Reflow uses the reflow state's border and padding, we
+  // actually just want to subtract what GetXULMinSize added, which is the
+  // result of GetXULBorderAndPadding.
+  nsMargin bp;
+  GetXULBorderAndPadding(bp);
+
+  result = minSize.ISize(wm) - LogicalMargin(wm, bp).IStartEnd(wm);
+
+  return result;
+}
+
+/* virtual */ nscoord
+nsLeafBoxFrame::GetPrefISize(nsRenderingContext *aRenderingContext)
+{
+  nscoord result;
+  DISPLAY_PREF_WIDTH(this, result);
+  nsBoxLayoutState state(PresContext(), aRenderingContext);
+
+  WritingMode wm = GetWritingMode();
+  LogicalSize prefSize(wm, GetXULPrefSize(state));
+
+  // GetXULPrefSize returns border-box size, and we want to return content
+  // inline-size.  Since Reflow uses the reflow state's border and padding, we
+  // actually just want to subtract what GetXULPrefSize added, which is the
+  // result of GetXULBorderAndPadding.
+  nsMargin bp;
+  GetXULBorderAndPadding(bp);
+
+  result = prefSize.ISize(wm) - LogicalMargin(wm, bp).IStartEnd(wm);
+
+  return result;
+}
+
+nscoord
+nsLeafBoxFrame::GetIntrinsicISize()
+{
+  // No intrinsic width
+  return 0;
+}
+
+LogicalSize
+nsLeafBoxFrame::ComputeAutoSize(nsRenderingContext* aRenderingContext,
+                                WritingMode         aWM,
+                                const LogicalSize&  aCBSize,
+                                nscoord             aAvailableISize,
+                                const LogicalSize&  aMargin,
+                                const LogicalSize&  aBorder,
+                                const LogicalSize&  aPadding,
+                                ComputeSizeFlags    aFlags)
+{
+  // Important: NOT calling our direct superclass here!
+  return nsFrame::ComputeAutoSize(aRenderingContext, aWM,
+                                  aCBSize, aAvailableISize,
+                                  aMargin, aBorder, aPadding, aFlags);
+}
+
+void
+nsLeafBoxFrame::Reflow(nsPresContext*   aPresContext,
+                     ReflowOutput&     aDesiredSize,
+                     const ReflowInput& aReflowInput,
+                     nsReflowStatus&          aStatus)
+{
+  // This is mostly a copy of nsBoxFrame::Reflow().
+  // We aren't able to share an implementation because of the frame
+  // class hierarchy.  If you make changes here, please keep
+  // nsBoxFrame::Reflow in sync.
+
+  MarkInReflow();
+  DO_GLOBAL_REFLOW_COUNT("nsLeafBoxFrame");
+  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
+
+  NS_ASSERTION(aReflowInput.ComputedWidth() >=0 &&
+               aReflowInput.ComputedHeight() >= 0, "Computed Size < 0");
+
+#ifdef DO_NOISY_REFLOW
+  printf("\n-------------Starting LeafBoxFrame Reflow ----------------------------\n");
+  printf("%p ** nsLBF::Reflow %d R: ", this, myCounter++);
+  switch (aReflowInput.reason) {
+    case eReflowReason_Initial:
+      printf("Ini");break;
+    case eReflowReason_Incremental:
+      printf("Inc");break;
+    case eReflowReason_Resize:
+      printf("Rsz");break;
+    case eReflowReason_StyleChange:
+      printf("Sty");break;
+    case eReflowReason_Dirty:
+      printf("Drt ");
+      break;
+    default:printf("<unknown>%d", aReflowInput.reason);break;
+  }
+  
+  printSize("AW", aReflowInput.AvailableWidth());
+  printSize("AH", aReflowInput.AvailableHeight());
+  printSize("CW", aReflowInput.ComputedWidth());
+  printSize("CH", aReflowInput.ComputedHeight());
+
+  printf(" *\n");
+
+#endif
+
+  aStatus = NS_FRAME_COMPLETE;
+
+  // create the layout state
+  nsBoxLayoutState state(aPresContext, aReflowInput.mRenderingContext);
+
+  nsSize computedSize(aReflowInput.ComputedWidth(),aReflowInput.ComputedHeight());
+
+  nsMargin m;
+  m = aReflowInput.ComputedPhysicalBorderPadding();
+
+  //GetXULBorderAndPadding(m);
+
+  // this happens sometimes. So lets handle it gracefully.
+  if (aReflowInput.ComputedHeight() == 0) {
+    nsSize minSize = GetXULMinSize(state);
+    computedSize.height = minSize.height - m.top - m.bottom;
+  }
+
+  nsSize prefSize(0,0);
+
+  // if we are told to layout intrinic then get our preferred size.
+  if (computedSize.width == NS_INTRINSICSIZE || computedSize.height == NS_INTRINSICSIZE) {
+     prefSize = GetXULPrefSize(state);
+     nsSize minSize = GetXULMinSize(state);
+     nsSize maxSize = GetXULMaxSize(state);
+     prefSize = BoundsCheck(minSize, prefSize, maxSize);
+  }
+
+  // get our desiredSize
+  if (aReflowInput.ComputedWidth() == NS_INTRINSICSIZE) {
+    computedSize.width = prefSize.width;
+  } else {
+    computedSize.width += m.left + m.right;
+  }
+
+  if (aReflowInput.ComputedHeight() == NS_INTRINSICSIZE) {
+    computedSize.height = prefSize.height;
+  } else {
+    computedSize.height += m.top + m.bottom;
+  }
+
+  // handle reflow state min and max sizes
+  // XXXbz the width handling here seems to be wrong, since
+  // mComputedMin/MaxWidth is a content-box size, whole
+  // computedSize.width is a border-box size...
+  if (computedSize.width > aReflowInput.ComputedMaxWidth())
+    computedSize.width = aReflowInput.ComputedMaxWidth();
+
+  if (computedSize.width < aReflowInput.ComputedMinWidth())
+    computedSize.width = aReflowInput.ComputedMinWidth();
+
+  // Now adjust computedSize.height for our min and max computed
+  // height.  The only problem is that those are content-box sizes,
+  // while computedSize.height is a border-box size.  So subtract off
+  // m.TopBottom() before adjusting, then readd it.
+  computedSize.height = std::max(0, computedSize.height - m.TopBottom());
+  computedSize.height = NS_CSS_MINMAX(computedSize.height,
+                                      aReflowInput.ComputedMinHeight(),
+                                      aReflowInput.ComputedMaxHeight());
+  computedSize.height += m.TopBottom();
+
+  nsRect r(mRect.x, mRect.y, computedSize.width, computedSize.height);
+
+  SetXULBounds(state, r);
+ 
+  // layout our children
+  XULLayout(state);
+  
+  // ok our child could have gotten bigger. So lets get its bounds
+  aDesiredSize.Width() = mRect.width;
+  aDesiredSize.Height() = mRect.height;
+  aDesiredSize.SetBlockStartAscent(GetXULBoxAscent(state));
+
+  // the overflow rect is set in SetXULBounds() above
+  aDesiredSize.mOverflowAreas = GetOverflowAreas();
+
+#ifdef DO_NOISY_REFLOW
+  {
+    printf("%p ** nsLBF(done) W:%d H:%d  ", this, aDesiredSize.Width(), aDesiredSize.Height());
+
+    if (maxElementWidth) {
+      printf("MW:%d\n", *maxElementWidth); 
+    } else {
+      printf("MW:?\n"); 
+    }
+
+  }
+#endif
+}
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+nsLeafBoxFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("LeafBox"), aResult);
+}
+#endif
+
+nsIAtom*
+nsLeafBoxFrame::GetType() const
+{
+  return nsGkAtoms::leafBoxFrame;
+}
+
+nsresult
+nsLeafBoxFrame::CharacterDataChanged(CharacterDataChangeInfo* aInfo)
+{
+  MarkIntrinsicISizesDirty();
+  return nsLeafFrame::CharacterDataChanged(aInfo);
+}
+
+/* virtual */ nsSize
+nsLeafBoxFrame::GetXULPrefSize(nsBoxLayoutState& aState)
+{
+    return nsBox::GetXULPrefSize(aState);
+}
+
+/* virtual */ nsSize
+nsLeafBoxFrame::GetXULMinSize(nsBoxLayoutState& aState)
+{
+    return nsBox::GetXULMinSize(aState);
+}
+
+/* virtual */ nsSize
+nsLeafBoxFrame::GetXULMaxSize(nsBoxLayoutState& aState)
+{
+    return nsBox::GetXULMaxSize(aState);
+}
+
+/* virtual */ nscoord
+nsLeafBoxFrame::GetXULFlex()
+{
+    return nsBox::GetXULFlex();
+}
+
+/* virtual */ nscoord
+nsLeafBoxFrame::GetXULBoxAscent(nsBoxLayoutState& aState)
+{
+    return nsBox::GetXULBoxAscent(aState);
+}
+
+/* virtual */ void
+nsLeafBoxFrame::MarkIntrinsicISizesDirty()
+{
+  // Don't call base class method, since everything it does is within an
+  // IsXULBoxWrapped check.
+}
+
+NS_IMETHODIMP
+nsLeafBoxFrame::DoXULLayout(nsBoxLayoutState& aState)
+{
+    return nsBox::DoXULLayout(aState);
+}
diff --git a/layout/xul/nsLeafBoxFrame.h b/layout/xul/nsLeafBoxFrame.h
new file mode 100644
index 0000000000..8aea598c83
--- /dev/null
+++ b/layout/xul/nsLeafBoxFrame.h
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsLeafBoxFrame_h___
+#define nsLeafBoxFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsLeafFrame.h"
+#include "nsBox.h"
+
+class nsLeafBoxFrame : public nsLeafFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewLeafBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+  virtual nsSize GetXULPrefSize(nsBoxLayoutState& aState) override;
+  virtual nsSize GetXULMinSize(nsBoxLayoutState& aState) override;
+  virtual nsSize GetXULMaxSize(nsBoxLayoutState& aState) override;
+  virtual nscoord GetXULFlex() override;
+  virtual nscoord GetXULBoxAscent(nsBoxLayoutState& aState) override;
+
+  virtual nsIAtom* GetType() const override;
+  virtual bool IsFrameOfType(uint32_t aFlags) const override
+  {
+    // This is bogus, but it's what we've always done.
+    // Note that nsLeafFrame is also eReplacedContainsBlock.
+    return nsLeafFrame::IsFrameOfType(aFlags &
+      ~(nsIFrame::eReplaced | nsIFrame::eReplacedContainsBlock | nsIFrame::eXULBox));
+  }
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override;
+#endif
+
+  // nsIHTMLReflow overrides
+
+  virtual void MarkIntrinsicISizesDirty() override;
+  virtual nscoord GetMinISize(nsRenderingContext *aRenderingContext) override;
+  virtual nscoord GetPrefISize(nsRenderingContext *aRenderingContext) override;
+
+  // Our auto size is that provided by nsFrame, not nsLeafFrame
+  virtual mozilla::LogicalSize
+  ComputeAutoSize(nsRenderingContext*         aRenderingContext,
+                  mozilla::WritingMode        aWM,
+                  const mozilla::LogicalSize& aCBSize,
+                  nscoord                     aAvailableISize,
+                  const mozilla::LogicalSize& aMargin,
+                  const mozilla::LogicalSize& aBorder,
+                  const mozilla::LogicalSize& aPadding,
+                  ComputeSizeFlags            aFlags) override;
+
+  virtual void Reflow(nsPresContext*           aPresContext,
+                      ReflowOutput&     aDesiredSize,
+                      const ReflowInput& aReflowInput,
+                      nsReflowStatus&          aStatus) override;
+
+  virtual nsresult CharacterDataChanged(CharacterDataChangeInfo* aInfo) override;
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         asPrevInFlow) override;
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+  virtual bool ComputesOwnOverflowArea() override { return false; }
+
+protected:
+
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aState) override;
+
+#ifdef DEBUG_LAYOUT
+  virtual void GetBoxName(nsAutoString& aName) override;
+#endif
+
+  virtual nscoord GetIntrinsicISize() override;
+
+ explicit nsLeafBoxFrame(nsStyleContext* aContext);
+
+private:
+
+ void UpdateMouseThrough();
+
+
+}; // class nsLeafBoxFrame
+
+#endif /* nsLeafBoxFrame_h___ */
diff --git a/layout/xul/nsListBoxBodyFrame.cpp b/layout/xul/nsListBoxBodyFrame.cpp
new file mode 100644
index 0000000000..8c4a5e2fdd
--- /dev/null
+++ b/layout/xul/nsListBoxBodyFrame.cpp
@@ -0,0 +1,1535 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsListBoxBodyFrame.h"
+
+#include "nsListBoxLayout.h"
+
+#include "mozilla/MathAlgorithms.h"
+#include "nsCOMPtr.h"
+#include "nsGridRowGroupLayout.h"
+#include "nsIServiceManager.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+#include "nsNameSpaceManager.h"
+#include "nsIDocument.h"
+#include "nsIDOMMouseEvent.h"
+#include "nsIDOMElement.h"
+#include "nsIDOMNodeList.h"
+#include "nsCSSFrameConstructor.h"
+#include "nsIScrollableFrame.h"
+#include "nsScrollbarFrame.h"
+#include "nsView.h"
+#include "nsViewManager.h"
+#include "nsStyleContext.h"
+#include "nsFontMetrics.h"
+#include "nsITimer.h"
+#include "mozilla/StyleSetHandle.h"
+#include "mozilla/StyleSetHandleInlines.h"
+#include "nsPIBoxObject.h"
+#include "nsLayoutUtils.h"
+#include "nsPIListBoxObject.h"
+#include "nsContentUtils.h"
+#include "ChildIterator.h"
+#include "nsRenderingContext.h"
+#include "prtime.h"
+#include <algorithm>
+
+#ifdef ACCESSIBILITY
+#include "nsAccessibilityService.h"
+#endif
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+/////////////// nsListScrollSmoother //////////////////
+
+/* A mediator used to smooth out scrolling. It works by seeing if 
+ * we have time to scroll the amount of rows requested. This is determined
+ * by measuring how long it takes to scroll a row. If we can scroll the 
+ * rows in time we do so. If not we start a timer and skip the request. We
+ * do this until the timer finally first because the user has stopped moving
+ * the mouse. Then do all the queued requests in on shot.
+ */
+
+// the longest amount of time that can go by before the use
+// notices it as a delay.
+#define USER_TIME_THRESHOLD 150000
+
+// how long it takes to layout a single row initial value.
+// we will time this after we scroll a few rows.
+#define TIME_PER_ROW_INITAL  50000
+
+// if we decide we can't layout the rows in the amount of time. How long
+// do we wait before checking again?
+#define SMOOTH_INTERVAL 100
+
+class nsListScrollSmoother final : public nsITimerCallback
+{
+private:
+  virtual ~nsListScrollSmoother();
+
+public:
+  NS_DECL_ISUPPORTS
+
+  explicit nsListScrollSmoother(nsListBoxBodyFrame* aOuter);
+
+  // nsITimerCallback
+  NS_DECL_NSITIMERCALLBACK
+
+  void Start();
+  void Stop();
+  bool IsRunning();
+
+  nsCOMPtr<nsITimer> mRepeatTimer;
+  int32_t mDelta;
+  nsListBoxBodyFrame* mOuter;
+}; 
+
+nsListScrollSmoother::nsListScrollSmoother(nsListBoxBodyFrame* aOuter)
+{
+  mDelta = 0;
+  mOuter = aOuter;
+}
+
+nsListScrollSmoother::~nsListScrollSmoother()
+{
+  Stop();
+}
+
+NS_IMETHODIMP
+nsListScrollSmoother::Notify(nsITimer *timer)
+{
+  Stop();
+
+  NS_ASSERTION(mOuter, "mOuter is null, see bug #68365");
+  if (!mOuter) return NS_OK;
+
+  // actually do some work.
+  mOuter->InternalPositionChangedCallback();
+  return NS_OK;
+}
+
+bool
+nsListScrollSmoother::IsRunning()
+{
+  return mRepeatTimer ? true : false;
+}
+
+void
+nsListScrollSmoother::Start()
+{
+  Stop();
+  mRepeatTimer = do_CreateInstance("@mozilla.org/timer;1");
+  mRepeatTimer->InitWithCallback(this, SMOOTH_INTERVAL, nsITimer::TYPE_ONE_SHOT);
+}
+
+void
+nsListScrollSmoother::Stop()
+{
+  if ( mRepeatTimer ) {
+    mRepeatTimer->Cancel();
+    mRepeatTimer = nullptr;
+  }
+}
+
+NS_IMPL_ISUPPORTS(nsListScrollSmoother, nsITimerCallback)
+
+/////////////// nsListBoxBodyFrame //////////////////
+
+nsListBoxBodyFrame::nsListBoxBodyFrame(nsStyleContext* aContext,
+                                       nsBoxLayout* aLayoutManager)
+  : nsBoxFrame(aContext, false, aLayoutManager),
+    mTopFrame(nullptr),
+    mBottomFrame(nullptr),
+    mLinkupFrame(nullptr),
+    mScrollSmoother(nullptr),
+    mRowsToPrepend(0),
+    mRowCount(-1),
+    mRowHeight(0),
+    mAvailableHeight(0),
+    mStringWidth(-1),
+    mCurrentIndex(0),
+    mOldIndex(0),
+    mYPosition(0),
+    mTimePerRow(TIME_PER_ROW_INITAL),
+    mRowHeightWasSet(false),
+    mScrolling(false),
+    mAdjustScroll(false),
+    mReflowCallbackPosted(false)
+{
+}
+
+nsListBoxBodyFrame::~nsListBoxBodyFrame()
+{
+  NS_IF_RELEASE(mScrollSmoother);
+
+#if USE_TIMER_TO_DELAY_SCROLLING
+  StopScrollTracking();
+  mAutoScrollTimer = nullptr;
+#endif
+
+}
+
+NS_QUERYFRAME_HEAD(nsListBoxBodyFrame)
+  NS_QUERYFRAME_ENTRY(nsIScrollbarMediator)
+  NS_QUERYFRAME_ENTRY(nsListBoxBodyFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsBoxFrame)
+
+////////// nsIFrame /////////////////
+
+void
+nsListBoxBodyFrame::Init(nsIContent*       aContent,
+                         nsContainerFrame* aParent, 
+                         nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+  // Don't call nsLayoutUtils::GetScrollableFrameFor since we are not its
+  // scrollframe child yet.
+  nsIScrollableFrame* scrollFrame = do_QueryFrame(aParent);
+  if (scrollFrame) {
+    nsIFrame* verticalScrollbar = scrollFrame->GetScrollbarBox(true);
+    nsScrollbarFrame* scrollbarFrame = do_QueryFrame(verticalScrollbar);
+    if (scrollbarFrame) {
+      scrollbarFrame->SetScrollbarMediatorContent(GetContent());
+    }
+  }
+  RefPtr<nsFontMetrics> fm =
+    nsLayoutUtils::GetFontMetricsForFrame(this, 1.0f);
+  mRowHeight = fm->MaxHeight();
+}
+
+void
+nsListBoxBodyFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  // make sure we cancel any posted callbacks.
+  if (mReflowCallbackPosted)
+     PresContext()->PresShell()->CancelReflowCallback(this);
+
+  // Revoke any pending position changed events
+  for (uint32_t i = 0; i < mPendingPositionChangeEvents.Length(); ++i) {
+    mPendingPositionChangeEvents[i]->Revoke();
+  }
+
+  // Make sure we tell our listbox's box object we're being destroyed.
+  if (mBoxObject) {
+    mBoxObject->ClearCachedValues();
+  }
+
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+nsresult
+nsListBoxBodyFrame::AttributeChanged(int32_t aNameSpaceID,
+                                     nsIAtom* aAttribute, 
+                                     int32_t aModType)
+{
+  nsresult rv = NS_OK;
+
+  if (aAttribute == nsGkAtoms::rows) {
+    PresContext()->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
+  }
+  else
+    rv = nsBoxFrame::AttributeChanged(aNameSpaceID, aAttribute, aModType);
+
+  return rv;
+ 
+}
+
+/* virtual */ void
+nsListBoxBodyFrame::MarkIntrinsicISizesDirty()
+{
+  mStringWidth = -1;
+  nsBoxFrame::MarkIntrinsicISizesDirty();
+}
+
+/////////// nsBox ///////////////
+
+NS_IMETHODIMP
+nsListBoxBodyFrame::DoXULLayout(nsBoxLayoutState& aBoxLayoutState)
+{
+  if (mScrolling)
+    aBoxLayoutState.SetPaintingDisabled(true);
+
+  nsresult rv = nsBoxFrame::DoXULLayout(aBoxLayoutState);
+
+  // determine the real height for the scrollable area from the total number
+  // of rows, since non-visible rows don't yet have frames
+  nsRect rect(nsPoint(0, 0), GetSize());
+  nsOverflowAreas overflow(rect, rect);
+  if (mLayoutManager) {
+    nsIFrame* childFrame = mFrames.FirstChild();
+    while (childFrame) {
+      ConsiderChildOverflow(overflow, childFrame);
+      childFrame = childFrame->GetNextSibling();
+    }
+
+    nsSize prefSize = mLayoutManager->GetXULPrefSize(this, aBoxLayoutState);
+    NS_FOR_FRAME_OVERFLOW_TYPES(otype) {
+      nsRect& o = overflow.Overflow(otype);
+      o.height = std::max(o.height, prefSize.height);
+    }
+  }
+  FinishAndStoreOverflow(overflow, GetSize());
+
+  if (mScrolling)
+    aBoxLayoutState.SetPaintingDisabled(false);
+
+  // if we are scrolled and the row height changed
+  // make sure we are scrolled to a correct index.
+  if (mAdjustScroll)
+     PostReflowCallback();
+
+  return rv;
+}
+
+nsSize
+nsListBoxBodyFrame::GetXULMinSizeForScrollArea(nsBoxLayoutState& aBoxLayoutState)
+{
+  nsSize result(0, 0);
+  if (nsContentUtils::HasNonEmptyAttr(GetContent(), kNameSpaceID_None,
+                                      nsGkAtoms::sizemode)) {
+    result = GetXULPrefSize(aBoxLayoutState);
+    result.height = 0;
+    nsIScrollableFrame* scrollFrame = nsLayoutUtils::GetScrollableFrameFor(this);
+    if (scrollFrame &&
+        scrollFrame->GetScrollbarStyles().mVertical == NS_STYLE_OVERFLOW_AUTO) {
+      nsMargin scrollbars =
+        scrollFrame->GetDesiredScrollbarSizes(&aBoxLayoutState);
+      result.width += scrollbars.left + scrollbars.right;
+    }
+  }
+  return result;
+}
+
+nsSize
+nsListBoxBodyFrame::GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState)
+{  
+  nsSize pref = nsBoxFrame::GetXULPrefSize(aBoxLayoutState);
+
+  int32_t size = GetFixedRowSize();
+  if (size > -1)
+    pref.height = size*GetRowHeightAppUnits();
+
+  nsIScrollableFrame* scrollFrame = nsLayoutUtils::GetScrollableFrameFor(this);
+  if (scrollFrame &&
+      scrollFrame->GetScrollbarStyles().mVertical == NS_STYLE_OVERFLOW_AUTO) {
+    nsMargin scrollbars = scrollFrame->GetDesiredScrollbarSizes(&aBoxLayoutState);
+    pref.width += scrollbars.left + scrollbars.right;
+  }
+  return pref;
+}
+
+///////////// nsIScrollbarMediator ///////////////
+
+void
+nsListBoxBodyFrame::ScrollByPage(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                                 nsIScrollbarMediator::ScrollSnapMode aSnap)
+{
+  // CSS Scroll Snapping is not enabled for XUL, aSnap is ignored
+  MOZ_ASSERT(aScrollbar != nullptr);
+  aScrollbar->SetIncrementToPage(aDirection);
+  nsWeakFrame weakFrame(this);
+  int32_t newPos = aScrollbar->MoveToNewPosition();
+  if (!weakFrame.IsAlive()) {
+    return;
+  }
+  UpdateIndex(newPos);
+}
+
+void
+nsListBoxBodyFrame::ScrollByWhole(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                                  nsIScrollbarMediator::ScrollSnapMode aSnap)
+{
+  // CSS Scroll Snapping is not enabled for XUL, aSnap is ignored
+  MOZ_ASSERT(aScrollbar != nullptr);
+  aScrollbar->SetIncrementToWhole(aDirection);
+  nsWeakFrame weakFrame(this);
+  int32_t newPos = aScrollbar->MoveToNewPosition();
+  if (!weakFrame.IsAlive()) {
+    return;
+  }
+  UpdateIndex(newPos);
+}
+
+void
+nsListBoxBodyFrame::ScrollByLine(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                                 nsIScrollbarMediator::ScrollSnapMode aSnap)
+{
+  // CSS Scroll Snapping is not enabled for XUL, aSnap is ignored
+  MOZ_ASSERT(aScrollbar != nullptr);
+  aScrollbar->SetIncrementToLine(aDirection);
+  nsWeakFrame weakFrame(this);
+  int32_t newPos = aScrollbar->MoveToNewPosition();
+  if (!weakFrame.IsAlive()) {
+    return;
+  }
+  UpdateIndex(newPos);
+}
+
+void
+nsListBoxBodyFrame::RepeatButtonScroll(nsScrollbarFrame* aScrollbar)
+{
+  nsWeakFrame weakFrame(this);
+  int32_t newPos = aScrollbar->MoveToNewPosition();
+  if (!weakFrame.IsAlive()) {
+    return;
+  }
+  UpdateIndex(newPos);
+}
+
+int32_t
+nsListBoxBodyFrame::ToRowIndex(nscoord aPos) const
+{
+  return NS_roundf(float(std::max(aPos, 0)) / mRowHeight);
+}
+
+void
+nsListBoxBodyFrame::ThumbMoved(nsScrollbarFrame* aScrollbar,
+                               nscoord aOldPos,
+                               nscoord aNewPos)
+{ 
+  if (mScrolling || mRowHeight == 0)
+    return;
+
+  int32_t newIndex = ToRowIndex(aNewPos);
+  if (newIndex == mCurrentIndex) {
+    return;
+  }
+  int32_t rowDelta = newIndex - mCurrentIndex;
+
+  nsListScrollSmoother* smoother = GetSmoother();
+
+  // if we can't scroll the rows in time then start a timer. We will eat
+  // events until the user stops moving and the timer stops.
+  if (smoother->IsRunning() || Abs(rowDelta)*mTimePerRow > USER_TIME_THRESHOLD) {
+
+     smoother->Stop();
+
+     smoother->mDelta = rowDelta;
+
+     smoother->Start();
+
+     return;
+  }
+
+  smoother->Stop();
+
+  mCurrentIndex = newIndex;
+  smoother->mDelta = 0;
+  
+  if (mCurrentIndex < 0) {
+    mCurrentIndex = 0;
+    return;
+  }
+  InternalPositionChanged(rowDelta < 0, Abs(rowDelta));
+}
+
+void
+nsListBoxBodyFrame::VisibilityChanged(bool aVisible)
+{
+  if (mRowHeight == 0)
+    return;
+
+  int32_t lastPageTopRow = GetRowCount() - (GetAvailableHeight() / mRowHeight);
+  if (lastPageTopRow < 0)
+    lastPageTopRow = 0;
+  int32_t delta = mCurrentIndex - lastPageTopRow;
+  if (delta > 0) {
+    mCurrentIndex = lastPageTopRow;
+    InternalPositionChanged(true, delta);
+  }
+}
+
+nsIFrame*
+nsListBoxBodyFrame::GetScrollbarBox(bool aVertical)
+{
+  nsIScrollableFrame* scrollFrame = nsLayoutUtils::GetScrollableFrameFor(this);
+  return scrollFrame ? scrollFrame->GetScrollbarBox(true) : nullptr;
+}
+
+void
+nsListBoxBodyFrame::UpdateIndex(int32_t aNewPos)
+{
+  int32_t newIndex = ToRowIndex(nsPresContext::CSSPixelsToAppUnits(aNewPos));
+  if (newIndex == mCurrentIndex) {
+    return;
+  }
+  bool up = newIndex < mCurrentIndex;
+  int32_t indexDelta = Abs(newIndex - mCurrentIndex);
+  mCurrentIndex = newIndex;
+  InternalPositionChanged(up, indexDelta);
+}
+ 
+///////////// nsIReflowCallback ///////////////
+
+bool
+nsListBoxBodyFrame::ReflowFinished()
+{
+  nsAutoScriptBlocker scriptBlocker;
+  // now create or destroy any rows as needed
+  CreateRows();
+
+  // keep scrollbar in sync
+  if (mAdjustScroll) {
+     VerticalScroll(mYPosition);
+     mAdjustScroll = false;
+  }
+
+  // if the row height changed then mark everything as a style change. 
+  // That will dirty the entire listbox
+  if (mRowHeightWasSet) {
+    PresContext()->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
+     int32_t pos = mCurrentIndex * mRowHeight;
+     if (mYPosition != pos) 
+       mAdjustScroll = true;
+    mRowHeightWasSet = false;
+  }
+
+  mReflowCallbackPosted = false;
+  return true;
+}
+
+void
+nsListBoxBodyFrame::ReflowCallbackCanceled()
+{
+  mReflowCallbackPosted = false;
+}
+
+///////// ListBoxObject ///////////////
+
+int32_t
+nsListBoxBodyFrame::GetNumberOfVisibleRows()
+{
+  return mRowHeight ? GetAvailableHeight() / mRowHeight : 0;
+}
+
+int32_t
+nsListBoxBodyFrame::GetIndexOfFirstVisibleRow()
+{
+  return mCurrentIndex;
+}
+
+nsresult
+nsListBoxBodyFrame::EnsureIndexIsVisible(int32_t aRowIndex)
+{
+  if (aRowIndex < 0)
+    return NS_ERROR_ILLEGAL_VALUE;
+
+  int32_t rows = 0;
+  if (mRowHeight)
+    rows = GetAvailableHeight()/mRowHeight;
+  if (rows <= 0)
+    rows = 1;
+  int32_t bottomIndex = mCurrentIndex + rows;
+  
+  // if row is visible, ignore
+  if (mCurrentIndex <= aRowIndex && aRowIndex < bottomIndex)
+    return NS_OK;
+
+  int32_t delta;
+
+  bool up = aRowIndex < mCurrentIndex;
+  if (up) {
+    delta = mCurrentIndex - aRowIndex;
+    mCurrentIndex = aRowIndex;
+  }
+  else {
+    // Check to be sure we're not scrolling off the bottom of the tree
+    if (aRowIndex >= GetRowCount())
+      return NS_ERROR_ILLEGAL_VALUE;
+
+    // Bring it just into view.
+    delta = 1 + (aRowIndex-bottomIndex);
+    mCurrentIndex += delta; 
+  }
+
+  // Safe to not go off an event here, since this is coming from the
+  // box object.
+  DoInternalPositionChangedSync(up, delta);
+  return NS_OK;
+}
+
+nsresult
+nsListBoxBodyFrame::ScrollByLines(int32_t aNumLines)
+{
+  int32_t scrollIndex = GetIndexOfFirstVisibleRow(),
+    visibleRows = GetNumberOfVisibleRows();
+
+  scrollIndex += aNumLines;
+  
+  if (scrollIndex < 0)
+    scrollIndex = 0;
+  else {
+    int32_t numRows = GetRowCount();
+    int32_t lastPageTopRow = numRows - visibleRows;
+    if (scrollIndex > lastPageTopRow)
+      scrollIndex = lastPageTopRow;
+  }
+  
+  ScrollToIndex(scrollIndex);
+
+  return NS_OK;
+}
+
+// walks the DOM to get the zero-based row index of the content
+nsresult
+nsListBoxBodyFrame::GetIndexOfItem(nsIDOMElement* aItem, int32_t* _retval)
+{
+  if (aItem) {
+    *_retval = 0;
+    nsCOMPtr<nsIContent> itemContent(do_QueryInterface(aItem));
+
+    FlattenedChildIterator iter(mContent);
+    for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+      // we hit a list row, count it
+      if (child->IsXULElement(nsGkAtoms::listitem)) {
+        // is this it?
+        if (child == itemContent)
+          return NS_OK;
+
+        ++(*_retval);
+      }
+    }
+  }
+
+  // not found
+  *_retval = -1;
+  return NS_OK;
+}
+
+nsresult
+nsListBoxBodyFrame::GetItemAtIndex(int32_t aIndex, nsIDOMElement** aItem)
+{
+  *aItem = nullptr;
+  if (aIndex < 0)
+    return NS_OK;
+
+  int32_t itemCount = 0;
+  FlattenedChildIterator iter(mContent);
+  for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+    // we hit a list row, check if it is the one we are looking for
+    if (child->IsXULElement(nsGkAtoms::listitem)) {
+      // is this it?
+      if (itemCount == aIndex) {
+        return CallQueryInterface(child, aItem);
+      }
+      ++itemCount;
+    }
+  }
+
+  // not found
+  return NS_OK;
+}
+
+/////////// nsListBoxBodyFrame ///////////////
+
+int32_t
+nsListBoxBodyFrame::GetRowCount()
+{
+  if (mRowCount < 0)
+    ComputeTotalRowCount();
+  return mRowCount;
+}
+
+int32_t
+nsListBoxBodyFrame::GetFixedRowSize()
+{
+  nsresult dummy;
+
+  nsAutoString rows;
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::rows, rows);
+  if (!rows.IsEmpty())
+    return rows.ToInteger(&dummy);
+ 
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::size, rows);
+
+  if (!rows.IsEmpty())
+    return rows.ToInteger(&dummy);
+
+  return -1;
+}
+
+void
+nsListBoxBodyFrame::SetRowHeight(nscoord aRowHeight)
+{ 
+  if (aRowHeight > mRowHeight) { 
+    mRowHeight = aRowHeight;
+
+    // signal we need to dirty everything 
+    // and we want to be notified after reflow
+    // so we can create or destory rows as needed
+    mRowHeightWasSet = true;
+    PostReflowCallback();
+  }
+}
+
+nscoord
+nsListBoxBodyFrame::GetAvailableHeight()
+{
+  nsIScrollableFrame* scrollFrame =
+    nsLayoutUtils::GetScrollableFrameFor(this);
+  if (scrollFrame) {
+    return scrollFrame->GetScrollPortRect().height;
+  }
+  return 0;
+}
+
+nscoord
+nsListBoxBodyFrame::GetYPosition()
+{
+  return mYPosition;
+}
+
+nscoord
+nsListBoxBodyFrame::ComputeIntrinsicISize(nsBoxLayoutState& aBoxLayoutState)
+{
+  if (mStringWidth != -1)
+    return mStringWidth;
+
+  nscoord largestWidth = 0;
+
+  int32_t index = 0;
+  nsCOMPtr<nsIDOMElement> firstRowEl;
+  GetItemAtIndex(index, getter_AddRefs(firstRowEl));
+  nsCOMPtr<nsIContent> firstRowContent(do_QueryInterface(firstRowEl));
+
+  if (firstRowContent) {
+    RefPtr<nsStyleContext> styleContext;
+    nsPresContext *presContext = aBoxLayoutState.PresContext();
+    styleContext = presContext->StyleSet()->
+      ResolveStyleFor(firstRowContent->AsElement(), nullptr);
+
+    nscoord width = 0;
+    nsMargin margin(0,0,0,0);
+
+    if (styleContext->StylePadding()->GetPadding(margin))
+      width += margin.LeftRight();
+    width += styleContext->StyleBorder()->GetComputedBorder().LeftRight();
+    if (styleContext->StyleMargin()->GetMargin(margin))
+      width += margin.LeftRight();
+
+    FlattenedChildIterator iter(mContent);
+    for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+      if (child->IsXULElement(nsGkAtoms::listitem)) {
+        nsRenderingContext* rendContext = aBoxLayoutState.GetRenderingContext();
+        if (rendContext) {
+          nsAutoString value;
+          uint32_t textCount = child->GetChildCount();
+          for (uint32_t j = 0; j < textCount; ++j) {
+            nsIContent* text = child->GetChildAt(j);
+            if (text && text->IsNodeOfType(nsINode::eTEXT)) {
+              text->AppendTextTo(value);
+            }
+          }
+
+          RefPtr<nsFontMetrics> fm =
+            nsLayoutUtils::GetFontMetricsForStyleContext(styleContext);
+
+          nscoord textWidth =
+            nsLayoutUtils::AppUnitWidthOfStringBidi(value, this, *fm,
+                                                    *rendContext);
+          textWidth += width;
+
+          if (textWidth > largestWidth) 
+            largestWidth = textWidth;
+        }
+      }
+    }
+  }
+
+  mStringWidth = largestWidth;
+  return mStringWidth;
+}
+
+void
+nsListBoxBodyFrame::ComputeTotalRowCount()
+{
+  mRowCount = 0;
+  FlattenedChildIterator iter(mContent);
+  for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+    if (child->IsXULElement(nsGkAtoms::listitem)) {
+      ++mRowCount;
+    }
+  }
+}
+
+void
+nsListBoxBodyFrame::PostReflowCallback()
+{
+  if (!mReflowCallbackPosted) {
+    mReflowCallbackPosted = true;
+    PresContext()->PresShell()->PostReflowCallback(this);
+  }
+}
+
+////////// scrolling
+
+nsresult
+nsListBoxBodyFrame::ScrollToIndex(int32_t aRowIndex)
+{
+  if (( aRowIndex < 0 ) || (mRowHeight == 0))
+    return NS_OK;
+    
+  int32_t newIndex = aRowIndex;
+  int32_t delta = mCurrentIndex > newIndex ? mCurrentIndex - newIndex : newIndex - mCurrentIndex;
+  bool up = newIndex < mCurrentIndex;
+
+  // Check to be sure we're not scrolling off the bottom of the tree
+  int32_t lastPageTopRow = GetRowCount() - (GetAvailableHeight() / mRowHeight);
+  if (lastPageTopRow < 0)
+    lastPageTopRow = 0;
+
+  if (aRowIndex > lastPageTopRow)
+    return NS_OK;
+
+  mCurrentIndex = newIndex;
+
+  nsWeakFrame weak(this);
+
+  // Since we're going to flush anyway, we need to not do this off an event
+  DoInternalPositionChangedSync(up, delta);
+
+  if (!weak.IsAlive()) {
+    return NS_OK;
+  }
+
+  // This change has to happen immediately.
+  // Flush any pending reflow commands.
+  // XXXbz why, exactly?
+  mContent->GetComposedDoc()->FlushPendingNotifications(Flush_Layout);
+
+  return NS_OK;
+}
+
+nsresult
+nsListBoxBodyFrame::InternalPositionChangedCallback()
+{
+  nsListScrollSmoother* smoother = GetSmoother();
+
+  if (smoother->mDelta == 0)
+    return NS_OK;
+
+  mCurrentIndex += smoother->mDelta;
+
+  if (mCurrentIndex < 0)
+    mCurrentIndex = 0;
+
+  return DoInternalPositionChangedSync(smoother->mDelta < 0,
+                                       smoother->mDelta < 0 ?
+                                         -smoother->mDelta : smoother->mDelta);
+}
+
+nsresult
+nsListBoxBodyFrame::InternalPositionChanged(bool aUp, int32_t aDelta)
+{
+  RefPtr<nsPositionChangedEvent> ev =
+    new nsPositionChangedEvent(this, aUp, aDelta);
+  nsresult rv = NS_DispatchToCurrentThread(ev);
+  if (NS_SUCCEEDED(rv)) {
+    if (!mPendingPositionChangeEvents.AppendElement(ev)) {
+      rv = NS_ERROR_OUT_OF_MEMORY;
+      ev->Revoke();
+    }
+  }
+  return rv;
+}
+
+nsresult
+nsListBoxBodyFrame::DoInternalPositionChangedSync(bool aUp, int32_t aDelta)
+{
+  nsWeakFrame weak(this);
+  
+  // Process all the pending position changes first
+  nsTArray< RefPtr<nsPositionChangedEvent> > temp;
+  temp.SwapElements(mPendingPositionChangeEvents);
+  for (uint32_t i = 0; i < temp.Length(); ++i) {
+    if (weak.IsAlive()) {
+      temp[i]->Run();
+    }
+    temp[i]->Revoke();
+  }
+
+  if (!weak.IsAlive()) {
+    return NS_OK;
+  }
+
+  return DoInternalPositionChanged(aUp, aDelta);
+}
+
+nsresult
+nsListBoxBodyFrame::DoInternalPositionChanged(bool aUp, int32_t aDelta)
+{
+  if (aDelta == 0)
+    return NS_OK;
+
+  RefPtr<nsPresContext> presContext(PresContext());
+  nsBoxLayoutState state(presContext);
+
+  // begin timing how long it takes to scroll a row
+  PRTime start = PR_Now();
+
+  nsWeakFrame weakThis(this);
+  mContent->GetComposedDoc()->FlushPendingNotifications(Flush_Layout);
+  if (!weakThis.IsAlive()) {
+    return NS_OK;
+  }
+
+  {
+    nsAutoScriptBlocker scriptBlocker;
+
+    int32_t visibleRows = 0;
+    if (mRowHeight)
+      visibleRows = GetAvailableHeight()/mRowHeight;
+  
+    if (aDelta < visibleRows) {
+      int32_t loseRows = aDelta;
+      if (aUp) {
+        // scrolling up, destroy rows from the bottom downwards
+        ReverseDestroyRows(loseRows);
+        mRowsToPrepend += aDelta;
+        mLinkupFrame = nullptr;
+      }
+      else {
+        // scrolling down, destroy rows from the top upwards
+        DestroyRows(loseRows);
+        mRowsToPrepend = 0;
+      }
+    }
+    else {
+      // We have scrolled so much that all of our current frames will
+      // go off screen, so blow them all away. Weeee!
+      nsIFrame *currBox = mFrames.FirstChild();
+      nsCSSFrameConstructor* fc = presContext->PresShell()->FrameConstructor();
+      fc->BeginUpdate();
+      while (currBox) {
+        nsIFrame *nextBox = currBox->GetNextSibling();
+        RemoveChildFrame(state, currBox);
+        currBox = nextBox;
+      }
+      fc->EndUpdate();
+    }
+
+    // clear frame markers so that CreateRows will re-create
+    mTopFrame = mBottomFrame = nullptr; 
+  
+    mYPosition = mCurrentIndex*mRowHeight;
+    mScrolling = true;
+    presContext->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eResize, NS_FRAME_HAS_DIRTY_CHILDREN);
+  }
+  if (!weakThis.IsAlive()) {
+    return NS_OK;
+  }
+  // Flush calls CreateRows
+  // XXXbz there has to be a better way to do this than flushing!
+  presContext->PresShell()->FlushPendingNotifications(Flush_Layout);
+  if (!weakThis.IsAlive()) {
+    return NS_OK;
+  }
+
+  mScrolling = false;
+  
+  VerticalScroll(mYPosition);
+
+  PRTime end = PR_Now();
+
+  int32_t newTime = int32_t(end - start) / aDelta;
+
+  // average old and new
+  mTimePerRow = (newTime + mTimePerRow)/2;
+  
+  return NS_OK;
+}
+
+nsListScrollSmoother* 
+nsListBoxBodyFrame::GetSmoother()
+{
+  if (!mScrollSmoother) {
+    mScrollSmoother = new nsListScrollSmoother(this);
+    NS_ASSERTION(mScrollSmoother, "out of memory");
+    NS_IF_ADDREF(mScrollSmoother);
+  }
+
+  return mScrollSmoother;
+}
+
+void
+nsListBoxBodyFrame::VerticalScroll(int32_t aPosition)
+{
+  nsIScrollableFrame* scrollFrame
+    = nsLayoutUtils::GetScrollableFrameFor(this);
+  if (!scrollFrame) {
+    return;
+  }
+
+  nsPoint scrollPosition = scrollFrame->GetScrollPosition();
+ 
+  nsWeakFrame weakFrame(this);
+  scrollFrame->ScrollTo(nsPoint(scrollPosition.x, aPosition),
+                        nsIScrollableFrame::INSTANT);
+  if (!weakFrame.IsAlive()) {
+    return;
+  }
+
+  mYPosition = aPosition;
+}
+
+////////// frame and box retrieval
+
+nsIFrame*
+nsListBoxBodyFrame::GetFirstFrame()
+{
+  mTopFrame = mFrames.FirstChild();
+  return mTopFrame;
+}
+
+nsIFrame*
+nsListBoxBodyFrame::GetLastFrame()
+{
+  return mFrames.LastChild();
+}
+
+bool
+nsListBoxBodyFrame::SupportsOrdinalsInChildren()
+{
+  return false;
+}
+
+////////// lazy row creation and destruction
+
+void
+nsListBoxBodyFrame::CreateRows()
+{
+  // Get our client rect.
+  nsRect clientRect;
+  GetXULClientRect(clientRect);
+
+  // Get the starting y position and the remaining available
+  // height.
+  nscoord availableHeight = GetAvailableHeight();
+  
+  if (availableHeight <= 0) {
+    bool fixed = (GetFixedRowSize() != -1);
+    if (fixed)
+      availableHeight = 10;
+    else
+      return;
+  }
+  
+  // get the first tree box. If there isn't one create one.
+  bool created = false;
+  nsIFrame* box = GetFirstItemBox(0, &created);
+  nscoord rowHeight = GetRowHeightAppUnits();
+  while (box) {  
+    if (created && mRowsToPrepend > 0)
+      --mRowsToPrepend;
+
+    // if the row height is 0 then fail. Wait until someone 
+    // laid out and sets the row height.
+    if (rowHeight == 0)
+        return;
+     
+    availableHeight -= rowHeight;
+    
+    // should we continue? Is the enought height?
+    if (!ContinueReflow(availableHeight))
+      break;
+
+    // get the next tree box. Create one if needed.
+    box = GetNextItemBox(box, 0, &created);
+  }
+
+  mRowsToPrepend = 0;
+  mLinkupFrame = nullptr;
+}
+
+void
+nsListBoxBodyFrame::DestroyRows(int32_t& aRowsToLose) 
+{
+  // We need to destroy frames until our row count has been properly
+  // reduced.  A reflow will then pick up and create the new frames.
+  nsIFrame* childFrame = GetFirstFrame();
+  nsBoxLayoutState state(PresContext());
+
+  nsCSSFrameConstructor* fc = PresContext()->PresShell()->FrameConstructor();
+  fc->BeginUpdate();
+  while (childFrame && aRowsToLose > 0) {
+    --aRowsToLose;
+
+    nsIFrame* nextFrame = childFrame->GetNextSibling();
+    RemoveChildFrame(state, childFrame);
+
+    mTopFrame = childFrame = nextFrame;
+  }
+  fc->EndUpdate();
+
+  PresContext()->PresShell()->
+    FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                     NS_FRAME_HAS_DIRTY_CHILDREN);
+}
+
+void
+nsListBoxBodyFrame::ReverseDestroyRows(int32_t& aRowsToLose) 
+{
+  // We need to destroy frames until our row count has been properly
+  // reduced.  A reflow will then pick up and create the new frames.
+  nsIFrame* childFrame = GetLastFrame();
+  nsBoxLayoutState state(PresContext());
+
+  nsCSSFrameConstructor* fc = PresContext()->PresShell()->FrameConstructor();
+  fc->BeginUpdate();
+  while (childFrame && aRowsToLose > 0) {
+    --aRowsToLose;
+    
+    nsIFrame* prevFrame;
+    prevFrame = childFrame->GetPrevSibling();
+    RemoveChildFrame(state, childFrame);
+
+    mBottomFrame = childFrame = prevFrame;
+  }
+  fc->EndUpdate();
+
+  PresContext()->PresShell()->
+    FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                     NS_FRAME_HAS_DIRTY_CHILDREN);
+}
+
+static bool
+IsListItemChild(nsListBoxBodyFrame* aParent, nsIContent* aChild,
+                nsIFrame** aChildFrame)
+{
+  *aChildFrame = nullptr;
+  if (!aChild->IsXULElement(nsGkAtoms::listitem)) {
+    return false;
+  }
+  nsIFrame* existingFrame = aChild->GetPrimaryFrame();
+  if (existingFrame && existingFrame->GetParent() != aParent) {
+    return false;
+  }
+  *aChildFrame = existingFrame;
+  return true;
+}
+
+//
+// Get the nsIFrame for the first visible listitem, and if none exists,
+// create one.
+//
+nsIFrame*
+nsListBoxBodyFrame::GetFirstItemBox(int32_t aOffset, bool* aCreated)
+{
+  if (aCreated)
+   *aCreated = false;
+
+  // Clear ourselves out.
+  mBottomFrame = mTopFrame;
+
+  if (mTopFrame) {
+    return mTopFrame->IsXULBoxFrame() ? mTopFrame : nullptr;
+  }
+
+  // top frame was cleared out
+  mTopFrame = GetFirstFrame();
+  mBottomFrame = mTopFrame;
+
+  if (mTopFrame && mRowsToPrepend <= 0) {
+    return mTopFrame->IsXULBoxFrame() ? mTopFrame : nullptr;
+  }
+
+  // At this point, we either have no frames at all, 
+  // or the user has scrolled upwards, leaving frames
+  // to be created at the top.  Let's determine which
+  // content needs a new frame first.
+
+  nsCOMPtr<nsIContent> startContent;
+  if (mTopFrame && mRowsToPrepend > 0) {
+    // We need to insert rows before the top frame
+    nsIContent* topContent = mTopFrame->GetContent();
+    nsIContent* topParent = topContent->GetParent();
+    int32_t contentIndex = topParent->IndexOf(topContent);
+    contentIndex -= aOffset;
+    if (contentIndex < 0)
+      return nullptr;
+    startContent = topParent->GetChildAt(contentIndex - mRowsToPrepend);
+  } else {
+    // This will be the first item frame we create.  Use the content
+    // at the current index, which is the first index scrolled into view
+    GetListItemContentAt(mCurrentIndex+aOffset, getter_AddRefs(startContent));
+  }
+
+  if (startContent) {  
+    nsIFrame* existingFrame;
+    if (!IsListItemChild(this, startContent, &existingFrame)) {
+      return GetFirstItemBox(++aOffset, aCreated);
+    }
+    if (existingFrame) {
+      return existingFrame->IsXULBoxFrame() ? existingFrame : nullptr;
+    }
+
+    // Either append the new frame, or prepend it (at index 0)
+    // XXX check here if frame was even created, it may not have been if
+    //     display: none was on listitem content
+    bool isAppend = mRowsToPrepend <= 0;
+    
+    nsPresContext* presContext = PresContext();
+    nsCSSFrameConstructor* fc = presContext->PresShell()->FrameConstructor();
+    nsIFrame* topFrame = nullptr;
+    fc->CreateListBoxContent(this, nullptr, startContent, &topFrame, isAppend);
+    mTopFrame = topFrame;
+    if (mTopFrame) {
+      if (aCreated)
+        *aCreated = true;
+
+      mBottomFrame = mTopFrame;
+
+      return mTopFrame->IsXULBoxFrame() ? mTopFrame : nullptr;
+    } else
+      return GetFirstItemBox(++aOffset, 0);
+  }
+
+  return nullptr;
+}
+
+//
+// Get the nsIFrame for the next visible listitem after aBox, and if none
+// exists, create one.
+//
+nsIFrame*
+nsListBoxBodyFrame::GetNextItemBox(nsIFrame* aBox, int32_t aOffset,
+                                   bool* aCreated)
+{
+  if (aCreated)
+    *aCreated = false;
+
+  nsIFrame* result = aBox->GetNextSibling();
+
+  if (!result || result == mLinkupFrame || mRowsToPrepend > 0) {
+    // No result found. See if there's a content node that wants a frame.
+    nsIContent* prevContent = aBox->GetContent();
+    nsIContent* parentContent = prevContent->GetParent();
+
+    int32_t i = parentContent->IndexOf(prevContent);
+
+    uint32_t childCount = parentContent->GetChildCount();
+    if (((uint32_t)i + aOffset + 1) < childCount) {
+      // There is a content node that wants a frame.
+      nsIContent *nextContent = parentContent->GetChildAt(i + aOffset + 1);
+
+      nsIFrame* existingFrame;
+      if (!IsListItemChild(this, nextContent, &existingFrame)) {
+        return GetNextItemBox(aBox, ++aOffset, aCreated);
+      }
+      if (!existingFrame) {
+        // Either append the new frame, or insert it after the current frame
+        bool isAppend = result != mLinkupFrame && mRowsToPrepend <= 0;
+        nsIFrame* prevFrame = isAppend ? nullptr : aBox;
+      
+        nsPresContext* presContext = PresContext();
+        nsCSSFrameConstructor* fc = presContext->PresShell()->FrameConstructor();
+        fc->CreateListBoxContent(this, prevFrame, nextContent,
+                                 &result, isAppend);
+
+        if (result) {
+          if (aCreated)
+            *aCreated = true;
+        } else
+          return GetNextItemBox(aBox, ++aOffset, aCreated);
+      } else {
+        result = existingFrame;
+      }
+            
+      mLinkupFrame = nullptr;
+    }
+  }
+
+  if (!result)
+    return nullptr;
+
+  mBottomFrame = result;
+
+  NS_ASSERTION(!result->IsXULBoxFrame() || result->GetParent() == this,
+               "returning frame that is not in childlist");
+
+  return result->IsXULBoxFrame() ? result : nullptr;
+}
+
+bool
+nsListBoxBodyFrame::ContinueReflow(nscoord height) 
+{
+#ifdef ACCESSIBILITY
+  if (nsIPresShell::IsAccessibilityActive()) {
+    // Create all the frames at once so screen readers and
+    // onscreen keyboards can see the full list right away
+    return true;
+  }
+#endif
+
+  if (height <= 0) {
+    nsIFrame* lastChild = GetLastFrame();
+    nsIFrame* startingPoint = mBottomFrame;
+    if (startingPoint == nullptr) {
+      // We just want to delete everything but the first item.
+      startingPoint = GetFirstFrame();
+    }
+
+    if (lastChild != startingPoint) {
+      // We have some hangers on (probably caused by shrinking the size of the window).
+      // Nuke them.
+      nsIFrame* currFrame = startingPoint->GetNextSibling();
+      nsBoxLayoutState state(PresContext());
+
+      nsCSSFrameConstructor* fc =
+        PresContext()->PresShell()->FrameConstructor();
+      fc->BeginUpdate();
+      while (currFrame) {
+        nsIFrame* nextFrame = currFrame->GetNextSibling();
+        RemoveChildFrame(state, currFrame);
+        currFrame = nextFrame;
+      }
+      fc->EndUpdate();
+
+      PresContext()->PresShell()->
+        FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                         NS_FRAME_HAS_DIRTY_CHILDREN);
+    }
+    return false;
+  }
+  else
+    return true;
+}
+
+NS_IMETHODIMP
+nsListBoxBodyFrame::ListBoxAppendFrames(nsFrameList& aFrameList)
+{
+  // append them after
+  nsBoxLayoutState state(PresContext());
+  const nsFrameList::Slice& newFrames = mFrames.AppendFrames(nullptr, aFrameList);
+  if (mLayoutManager)
+    mLayoutManager->ChildrenAppended(this, state, newFrames);
+  PresContext()->PresShell()->
+    FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                     NS_FRAME_HAS_DIRTY_CHILDREN);
+  
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsListBoxBodyFrame::ListBoxInsertFrames(nsIFrame* aPrevFrame,
+                                        nsFrameList& aFrameList)
+{
+  // insert the frames to our info list
+  nsBoxLayoutState state(PresContext());
+  const nsFrameList::Slice& newFrames =
+    mFrames.InsertFrames(nullptr, aPrevFrame, aFrameList);
+  if (mLayoutManager)
+    mLayoutManager->ChildrenInserted(this, state, aPrevFrame, newFrames);
+  PresContext()->PresShell()->
+    FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                     NS_FRAME_HAS_DIRTY_CHILDREN);
+
+  return NS_OK;
+}
+
+// 
+// Called by nsCSSFrameConstructor when a new listitem content is inserted.
+//
+void
+nsListBoxBodyFrame::OnContentInserted(nsIContent* aChildContent)
+{
+  if (mRowCount >= 0)
+    ++mRowCount;
+
+  // The RDF content builder will build content nodes such that they are all 
+  // ready when OnContentInserted is first called, meaning the first call
+  // to CreateRows will create all the frames, but OnContentInserted will
+  // still be called again for each content node - so we need to make sure
+  // that the frame for each content node hasn't already been created.
+  nsIFrame* childFrame = aChildContent->GetPrimaryFrame();
+  if (childFrame)
+    return;
+
+  int32_t siblingIndex;
+  nsCOMPtr<nsIContent> nextSiblingContent;
+  GetListItemNextSibling(aChildContent, getter_AddRefs(nextSiblingContent), siblingIndex);
+  
+  // if we're inserting our item before the first visible content,
+  // then we need to shift all rows down by one
+  if (siblingIndex >= 0 &&  siblingIndex-1 <= mCurrentIndex) {
+    mTopFrame = nullptr;
+    mRowsToPrepend = 1;
+  } else if (nextSiblingContent) {
+    // we may be inserting before a frame that is on screen
+    nsIFrame* nextSiblingFrame = nextSiblingContent->GetPrimaryFrame();
+    mLinkupFrame = nextSiblingFrame;
+  }
+  
+  CreateRows();
+  PresContext()->PresShell()->
+    FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                     NS_FRAME_HAS_DIRTY_CHILDREN);
+}
+
+// 
+// Called by nsCSSFrameConstructor when listitem content is removed.
+//
+void
+nsListBoxBodyFrame::OnContentRemoved(nsPresContext* aPresContext,
+                                     nsIContent* aContainer,
+                                     nsIFrame* aChildFrame,
+                                     nsIContent* aOldNextSibling)
+{
+  NS_ASSERTION(!aChildFrame || aChildFrame->GetParent() == this,
+               "Removing frame that's not our child... Not good");
+  
+  if (mRowCount >= 0)
+    --mRowCount;
+
+  if (aContainer) {
+    if (!aChildFrame) {
+      // The row we are removing is out of view, so we need to try to
+      // determine the index of its next sibling.
+      int32_t siblingIndex = -1;
+      if (aOldNextSibling) {
+        nsCOMPtr<nsIContent> nextSiblingContent;
+        GetListItemNextSibling(aOldNextSibling,
+                               getter_AddRefs(nextSiblingContent),
+                               siblingIndex);
+      }
+    
+      // if the row being removed is off-screen and above the top frame, we need to
+      // adjust our top index and tell the scrollbar to shift up one row.
+      if (siblingIndex >= 0 && siblingIndex-1 < mCurrentIndex) {
+        NS_PRECONDITION(mCurrentIndex > 0, "mCurrentIndex > 0");
+        --mCurrentIndex;
+        mYPosition = mCurrentIndex*mRowHeight;
+        nsWeakFrame weakChildFrame(aChildFrame);
+        VerticalScroll(mYPosition);
+        if (!weakChildFrame.IsAlive()) {
+          return;
+        }
+      }
+    } else if (mCurrentIndex > 0) {
+      // At this point, we know we have a scrollbar, and we need to know 
+      // if we are scrolled to the last row.  In this case, the behavior
+      // of the scrollbar is to stay locked to the bottom.  Since we are
+      // removing visible content, the first visible row will have to move
+      // down by one, and we will have to insert a new frame at the top.
+
+      // if the last content node has a frame, we are scrolled to the bottom
+      nsIContent* lastChild = nullptr;
+      FlattenedChildIterator iter(mContent);
+      for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+        lastChild = child;
+      }
+
+      if (lastChild) {
+        nsIFrame* lastChildFrame = lastChild->GetPrimaryFrame();
+
+        if (lastChildFrame) {
+          mTopFrame = nullptr;
+          mRowsToPrepend = 1;
+          --mCurrentIndex;
+          mYPosition = mCurrentIndex*mRowHeight;
+          nsWeakFrame weakChildFrame(aChildFrame);
+          VerticalScroll(mYPosition);
+          if (!weakChildFrame.IsAlive()) {
+            return;
+          }
+        }
+      }
+    }
+  }
+
+  // if we're removing the top row, the new top row is the next row
+  if (mTopFrame && mTopFrame == aChildFrame)
+    mTopFrame = mTopFrame->GetNextSibling();
+
+  // Go ahead and delete the frame.
+  nsBoxLayoutState state(aPresContext);
+  if (aChildFrame) {
+    RemoveChildFrame(state, aChildFrame);
+  }
+
+  PresContext()->PresShell()->
+    FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                     NS_FRAME_HAS_DIRTY_CHILDREN);
+}
+
+void
+nsListBoxBodyFrame::GetListItemContentAt(int32_t aIndex, nsIContent** aContent)
+{
+  *aContent = nullptr;
+
+  int32_t itemsFound = 0;
+  FlattenedChildIterator iter(mContent);
+  for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+    if (child->IsXULElement(nsGkAtoms::listitem)) {
+      ++itemsFound;
+      if (itemsFound-1 == aIndex) {
+        *aContent = child;
+        NS_IF_ADDREF(*aContent);
+        return;
+      }
+    }
+  }
+}
+
+void
+nsListBoxBodyFrame::GetListItemNextSibling(nsIContent* aListItem, nsIContent** aContent, int32_t& aSiblingIndex)
+{
+  *aContent = nullptr;
+  aSiblingIndex = -1;
+  nsIContent *prevKid = nullptr;
+  FlattenedChildIterator iter(mContent);
+  for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+    if (child->IsXULElement(nsGkAtoms::listitem)) {
+      ++aSiblingIndex;
+      if (prevKid == aListItem) {
+        *aContent = child;
+        NS_IF_ADDREF(*aContent);
+        return;
+      }
+    }
+    prevKid = child;
+  }
+
+  aSiblingIndex = -1; // no match, so there is no next sibling
+}
+
+void
+nsListBoxBodyFrame::RemoveChildFrame(nsBoxLayoutState &aState,
+                                     nsIFrame         *aFrame)
+{
+  MOZ_ASSERT(mFrames.ContainsFrame(aFrame));
+  MOZ_ASSERT(aFrame != GetContentInsertionFrame());
+
+#ifdef ACCESSIBILITY
+  nsAccessibilityService* accService = nsIPresShell::AccService();
+  if (accService) {
+    nsIContent* content = aFrame->GetContent();
+    accService->ContentRemoved(PresContext()->PresShell(), content);
+  }
+#endif
+
+  mFrames.RemoveFrame(aFrame);
+  if (mLayoutManager)
+    mLayoutManager->ChildrenRemoved(this, aState, aFrame);
+  aFrame->Destroy();
+}
+
+// Creation Routines ///////////////////////////////////////////////////////////////////////
+
+already_AddRefed<nsBoxLayout> NS_NewListBoxLayout();
+
+nsIFrame*
+NS_NewListBoxBodyFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  nsCOMPtr<nsBoxLayout> layout = NS_NewListBoxLayout();
+  return new (aPresShell) nsListBoxBodyFrame(aContext, layout);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsListBoxBodyFrame)
diff --git a/layout/xul/nsListBoxBodyFrame.h b/layout/xul/nsListBoxBodyFrame.h
new file mode 100644
index 0000000000..57bbf0257c
--- /dev/null
+++ b/layout/xul/nsListBoxBodyFrame.h
@@ -0,0 +1,217 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsListBoxBodyFrame_h
+#define nsListBoxBodyFrame_h
+
+#include "mozilla/Attributes.h"
+#include "nsCOMPtr.h"
+#include "nsBoxFrame.h"
+#include "nsIScrollbarMediator.h"
+#include "nsIReflowCallback.h"
+#include "nsBoxLayoutState.h"
+#include "nsThreadUtils.h"
+#include "nsPIBoxObject.h"
+
+class nsPresContext;
+class nsListScrollSmoother;
+nsIFrame* NS_NewListBoxBodyFrame(nsIPresShell* aPresShell,
+                                 nsStyleContext* aContext);
+
+class nsListBoxBodyFrame final : public nsBoxFrame,
+                                 public nsIScrollbarMediator,
+                                 public nsIReflowCallback
+{
+  nsListBoxBodyFrame(nsStyleContext* aContext,
+                     nsBoxLayout* aLayoutManager);
+  virtual ~nsListBoxBodyFrame();
+
+public:
+  NS_DECL_QUERYFRAME_TARGET(nsListBoxBodyFrame)
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  // non-virtual ListBoxObject
+  int32_t GetNumberOfVisibleRows();
+  int32_t GetIndexOfFirstVisibleRow();
+  nsresult EnsureIndexIsVisible(int32_t aRowIndex);
+  nsresult ScrollToIndex(int32_t aRowIndex);
+  nsresult ScrollByLines(int32_t aNumLines);
+  nsresult GetItemAtIndex(int32_t aIndex, nsIDOMElement **aResult);
+  nsresult GetIndexOfItem(nsIDOMElement *aItem, int32_t *aResult);
+
+  friend nsIFrame* NS_NewListBoxBodyFrame(nsIPresShell* aPresShell,
+                                          nsStyleContext* aContext);
+  
+  // nsIFrame
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent, 
+                    nsIFrame*         aPrevInFlow) override;
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID, nsIAtom* aAttribute, int32_t aModType) override;
+
+  // nsIScrollbarMediator
+  virtual void ScrollByPage(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                            nsIScrollbarMediator::ScrollSnapMode snapMode
+                              = nsIScrollbarMediator::DISABLE_SNAP) override;
+  virtual void ScrollByWhole(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                             nsIScrollbarMediator::ScrollSnapMode snapMode
+                               = nsIScrollbarMediator::DISABLE_SNAP) override;
+  virtual void ScrollByLine(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                            nsIScrollbarMediator::ScrollSnapMode snapMode
+                              = nsIScrollbarMediator::DISABLE_SNAP) override;
+  virtual void RepeatButtonScroll(nsScrollbarFrame* aScrollbar) override;
+  virtual void ThumbMoved(nsScrollbarFrame* aScrollbar,
+                          int32_t aOldPos,
+                          int32_t aNewPos) override;
+  virtual void ScrollbarReleased(nsScrollbarFrame* aScrollbar) override {}
+  virtual void VisibilityChanged(bool aVisible) override;
+  virtual nsIFrame* GetScrollbarBox(bool aVertical) override;
+  virtual void ScrollbarActivityStarted() const override {}
+  virtual void ScrollbarActivityStopped() const override {}
+  virtual bool IsScrollbarOnRight() const override {
+    return (StyleVisibility()->mDirection == NS_STYLE_DIRECTION_LTR);
+  }
+  virtual bool ShouldSuppressScrollbarRepaints() const override {
+    return false;
+  }
+
+
+  // nsIReflowCallback
+  virtual bool ReflowFinished() override;
+  virtual void ReflowCallbackCanceled() override;
+
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual void MarkIntrinsicISizesDirty() override;
+
+  virtual nsSize GetXULMinSizeForScrollArea(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState) override;
+
+  // size calculation 
+  int32_t GetRowCount();
+  int32_t GetRowHeightAppUnits() { return mRowHeight; }
+  int32_t GetFixedRowSize();
+  void SetRowHeight(nscoord aRowHeight);
+  nscoord GetYPosition();
+  nscoord GetAvailableHeight();
+  nscoord ComputeIntrinsicISize(nsBoxLayoutState& aBoxLayoutState);
+
+  // scrolling
+  nsresult InternalPositionChangedCallback();
+  nsresult InternalPositionChanged(bool aUp, int32_t aDelta);
+  // Process pending position changed events, then do the position change.
+  // This can wipe out the frametree.
+  nsresult DoInternalPositionChangedSync(bool aUp, int32_t aDelta);
+  // Actually do the internal position change.  This can wipe out the frametree
+  nsresult DoInternalPositionChanged(bool aUp, int32_t aDelta);
+  nsListScrollSmoother* GetSmoother();
+  void VerticalScroll(int32_t aDelta);
+  // Update the scroll index given a position, in CSS pixels
+  void UpdateIndex(int32_t aNewPos);
+
+  // frames
+  nsIFrame* GetFirstFrame();
+  nsIFrame* GetLastFrame();
+
+  // lazy row creation and destruction
+  void CreateRows();
+  void DestroyRows(int32_t& aRowsToLose);
+  void ReverseDestroyRows(int32_t& aRowsToLose);
+  nsIFrame* GetFirstItemBox(int32_t aOffset, bool* aCreated);
+  nsIFrame* GetNextItemBox(nsIFrame* aBox, int32_t aOffset, bool* aCreated);
+  bool ContinueReflow(nscoord height);
+  NS_IMETHOD ListBoxAppendFrames(nsFrameList& aFrameList);
+  NS_IMETHOD ListBoxInsertFrames(nsIFrame* aPrevFrame, nsFrameList& aFrameList);
+  void OnContentInserted(nsIContent* aContent);
+  void OnContentRemoved(nsPresContext* aPresContext,  nsIContent* aContainer,
+                        nsIFrame* aChildFrame, nsIContent* aOldNextSibling);
+
+  void GetListItemContentAt(int32_t aIndex, nsIContent** aContent);
+  void GetListItemNextSibling(nsIContent* aListItem, nsIContent** aContent, int32_t& aSiblingIndex);
+
+  void PostReflowCallback();
+
+  bool SetBoxObject(nsPIBoxObject* aBoxObject)
+  {
+    NS_ENSURE_TRUE(!mBoxObject, false);
+    mBoxObject = aBoxObject;
+    return true;
+  }
+
+  virtual bool SupportsOrdinalsInChildren() override;
+
+  virtual bool ComputesOwnOverflowArea() override { return true; }
+
+protected:
+  class nsPositionChangedEvent;
+  friend class nsPositionChangedEvent;
+
+  class nsPositionChangedEvent : public mozilla::Runnable
+  {
+  public:
+    nsPositionChangedEvent(nsListBoxBodyFrame* aFrame,
+                           bool aUp, int32_t aDelta) :
+      mFrame(aFrame), mUp(aUp), mDelta(aDelta)
+    {}
+  
+    NS_IMETHOD Run() override
+    {
+      if (!mFrame) {
+        return NS_OK;
+      }
+
+      mFrame->mPendingPositionChangeEvents.RemoveElement(this);
+
+      return mFrame->DoInternalPositionChanged(mUp, mDelta);
+    }
+
+    void Revoke() {
+      mFrame = nullptr;
+    }
+
+    nsListBoxBodyFrame* mFrame;
+    bool mUp;
+    int32_t mDelta;
+  };
+
+  void ComputeTotalRowCount();
+  int32_t ToRowIndex(nscoord aPos) const;
+  void RemoveChildFrame(nsBoxLayoutState &aState, nsIFrame *aChild);
+
+  nsTArray< RefPtr<nsPositionChangedEvent> > mPendingPositionChangeEvents;
+  nsCOMPtr<nsPIBoxObject> mBoxObject;
+
+  // frame markers
+  nsWeakFrame mTopFrame;
+  nsIFrame* mBottomFrame;
+  nsIFrame* mLinkupFrame;
+
+  nsListScrollSmoother* mScrollSmoother;
+
+  int32_t mRowsToPrepend;
+
+  // row height
+  int32_t mRowCount;
+  nscoord mRowHeight;
+  nscoord mAvailableHeight;
+  nscoord mStringWidth;
+
+  // scrolling
+  int32_t mCurrentIndex; // Row-based
+  int32_t mOldIndex; 
+  int32_t mYPosition;
+  int32_t mTimePerRow;
+
+  // row height
+  bool mRowHeightWasSet;
+  // scrolling
+  bool mScrolling;
+  bool mAdjustScroll;
+
+  bool mReflowCallbackPosted;
+};
+
+#endif // nsListBoxBodyFrame_h
diff --git a/layout/xul/nsListBoxLayout.cpp b/layout/xul/nsListBoxLayout.cpp
new file mode 100644
index 0000000000..a2f915191a
--- /dev/null
+++ b/layout/xul/nsListBoxLayout.cpp
@@ -0,0 +1,212 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsListBoxLayout.h"
+
+#include "nsListBoxBodyFrame.h"
+#include "nsBox.h"
+#include "nsBoxLayoutState.h"
+#include "nsIScrollableFrame.h"
+#include "nsIReflowCallback.h"
+#include "mozilla/dom/NameSpaceConstants.h"
+#include "nsGkAtoms.h"
+#include "nsContentUtils.h"
+
+nsListBoxLayout::nsListBoxLayout() : nsGridRowGroupLayout()
+{
+}
+
+////////// nsBoxLayout //////////////
+
+nsSize
+nsListBoxLayout::GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  nsSize pref = nsGridRowGroupLayout::GetXULPrefSize(aBox, aBoxLayoutState);
+
+  nsListBoxBodyFrame* frame = static_cast<nsListBoxBodyFrame*>(aBox);
+  if (frame) {
+    nscoord rowheight = frame->GetRowHeightAppUnits();
+    pref.height = frame->GetRowCount() * rowheight;
+    // Pad the height.
+    nscoord y = frame->GetAvailableHeight();
+    if (pref.height > y && y > 0 && rowheight > 0) {
+      nscoord m = (pref.height-y)%rowheight;
+      nscoord remainder = m == 0 ? 0 : rowheight - m;
+      pref.height += remainder;
+    }
+    if (nsContentUtils::HasNonEmptyAttr(frame->GetContent(), kNameSpaceID_None,
+                                        nsGkAtoms::sizemode)) {
+      nscoord width = frame->ComputeIntrinsicISize(aBoxLayoutState);
+      if (width > pref.width)
+        pref.width = width;
+    }
+  }
+  return pref;
+}
+
+nsSize
+nsListBoxLayout::GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  nsSize minSize = nsGridRowGroupLayout::GetXULMinSize(aBox, aBoxLayoutState);
+
+  nsListBoxBodyFrame* frame = static_cast<nsListBoxBodyFrame*>(aBox);
+  if (frame) {
+    nscoord rowheight = frame->GetRowHeightAppUnits();
+    minSize.height = frame->GetRowCount() * rowheight;
+    // Pad the height.
+    nscoord y = frame->GetAvailableHeight();
+    if (minSize.height > y && y > 0 && rowheight > 0) {
+      nscoord m = (minSize.height-y)%rowheight;
+      nscoord remainder = m == 0 ? 0 : rowheight - m;
+      minSize.height += remainder;
+    }
+    if (nsContentUtils::HasNonEmptyAttr(frame->GetContent(), kNameSpaceID_None,
+                                        nsGkAtoms::sizemode)) {
+      nscoord width = frame->ComputeIntrinsicISize(aBoxLayoutState);
+      if (width > minSize.width)
+        minSize.width = width;
+    }
+  }
+  return minSize;
+}
+
+nsSize
+nsListBoxLayout::GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState)
+{
+  nsSize maxSize = nsGridRowGroupLayout::GetXULMaxSize(aBox, aBoxLayoutState);
+
+  nsListBoxBodyFrame* frame = static_cast<nsListBoxBodyFrame*>(aBox);
+  if (frame) {
+    nscoord rowheight = frame->GetRowHeightAppUnits();
+    maxSize.height = frame->GetRowCount() * rowheight;
+    // Pad the height.
+    nscoord y = frame->GetAvailableHeight();
+    if (maxSize.height > y && y > 0 && rowheight > 0) {
+      nscoord m = (maxSize.height-y)%rowheight;
+      nscoord remainder = m == 0 ? 0 : rowheight - m;
+      maxSize.height += remainder;
+    }
+  }
+  return maxSize;
+}
+
+NS_IMETHODIMP
+nsListBoxLayout::XULLayout(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  return LayoutInternal(aBox, aState);
+}
+
+
+/////////// nsListBoxLayout /////////////////////////
+
+/**
+ * Called to layout our our children. Does no frame construction
+ */
+NS_IMETHODIMP
+nsListBoxLayout::LayoutInternal(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  int32_t redrawStart = -1;
+
+  // Get the start y position.
+  nsListBoxBodyFrame* body = static_cast<nsListBoxBodyFrame*>(aBox);
+  if (!body) {
+    NS_ERROR("Frame encountered that isn't a listboxbody!");
+    return NS_ERROR_FAILURE;
+  }
+
+  nsMargin margin;
+
+  // Get our client rect.
+  nsRect clientRect;
+  aBox->GetXULClientRect(clientRect);
+
+  // Get the starting y position and the remaining available
+  // height.
+  nscoord availableHeight = body->GetAvailableHeight();
+  nscoord yOffset = body->GetYPosition();
+  
+  if (availableHeight <= 0) {
+    bool fixed = (body->GetFixedRowSize() != -1);
+    if (fixed)
+      availableHeight = 10;
+    else
+      return NS_OK;
+  }
+
+  // run through all our currently created children
+  nsIFrame* box = nsBox::GetChildXULBox(body);
+
+  // if the reason is resize or initial we must relayout.
+  nscoord rowHeight = body->GetRowHeightAppUnits();
+
+  while (box) {
+    // If this box is dirty or if it has dirty children, we
+    // call layout on it.
+    nsRect childRect(box->GetRect());
+    box->GetXULMargin(margin);
+    
+    // relayout if we must or we are dirty or some of our children are dirty
+    //   or the client area is wider than us
+    // XXXldb There should probably be a resize check here too!
+    if (NS_SUBTREE_DIRTY(box) || childRect.width < clientRect.width) {
+      childRect.x = 0;
+      childRect.y = yOffset;
+      childRect.width = clientRect.width;
+      
+      nsSize size = box->GetXULPrefSize(aState);
+      body->SetRowHeight(size.height);
+      
+      childRect.height = rowHeight;
+
+      childRect.Deflate(margin);
+      box->SetXULBounds(aState, childRect);
+      box->XULLayout(aState);
+    } else {
+      // if the child did not need to be relayed out. Then its easy.
+      // Place the child by just grabbing its rect and adjusting the y.
+      int32_t newPos = yOffset+margin.top;
+
+      // are we pushing down or pulling up any rows?
+      // Then we may have to redraw everything below the moved 
+      // rows.
+      if (redrawStart == -1 && childRect.y != newPos)
+        redrawStart = newPos;
+
+      childRect.y = newPos;
+      box->SetXULBounds(aState, childRect);
+    }
+
+    // Ok now the available size gets smaller and we move the
+    // starting position of the next child down some.
+    nscoord size = childRect.height + margin.top + margin.bottom;
+
+    yOffset += size;
+    availableHeight -= size;
+    
+    box = nsBox::GetNextXULBox(box);
+  }
+  
+  // We have enough available height left to add some more rows
+  // Since we can't do this during layout, we post a callback
+  // that will be processed after the reflow completes.
+  body->PostReflowCallback();
+    
+  // if rows were pushed down or pulled up because some rows were added
+  // before them then redraw everything under the inserted rows. The inserted
+  // rows will automatically be redrawn because the were marked dirty on insertion.
+  if (redrawStart > -1) {
+    aBox->XULRedraw(aState);
+  }
+
+  return NS_OK;
+}
+
+// Creation Routines ///////////////////////////////////////////////////////////////////////
+
+already_AddRefed<nsBoxLayout> NS_NewListBoxLayout()
+{
+  RefPtr<nsBoxLayout> layout = new nsListBoxLayout();
+  return layout.forget();
+} 
diff --git a/layout/xul/nsListBoxLayout.h b/layout/xul/nsListBoxLayout.h
new file mode 100644
index 0000000000..d1f9788433
--- /dev/null
+++ b/layout/xul/nsListBoxLayout.h
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsListBoxLayout_h___
+#define nsListBoxLayout_h___
+
+#include "mozilla/Attributes.h"
+#include "nsGridRowGroupLayout.h"
+
+class nsIFrame;
+typedef class nsIFrame nsIFrame;
+class nsBoxLayoutState;
+
+class nsListBoxLayout : public nsGridRowGroupLayout
+{
+public:
+  nsListBoxLayout();
+
+  // nsBoxLayout
+  NS_IMETHOD XULLayout(nsIFrame* aBox, nsBoxLayoutState& aState) override;
+  virtual nsSize GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+
+protected:
+  NS_IMETHOD LayoutInternal(nsIFrame* aBox, nsBoxLayoutState& aState);
+};
+
+#endif
+
diff --git a/layout/xul/nsListItemFrame.cpp b/layout/xul/nsListItemFrame.cpp
new file mode 100644
index 0000000000..1776f1b6cb
--- /dev/null
+++ b/layout/xul/nsListItemFrame.cpp
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsListItemFrame.h"
+
+#include <algorithm>
+
+#include "nsCOMPtr.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsDisplayList.h"
+#include "nsBoxLayout.h"
+#include "nsIContent.h"
+
+nsListItemFrame::nsListItemFrame(nsStyleContext* aContext,
+                                 bool aIsRoot,
+                                 nsBoxLayout* aLayoutManager)
+  : nsGridRowLeafFrame(aContext, aIsRoot, aLayoutManager) 
+{
+}
+
+nsListItemFrame::~nsListItemFrame()
+{
+}
+
+nsSize
+nsListItemFrame::GetXULPrefSize(nsBoxLayoutState& aState)
+{
+  nsSize size = nsBoxFrame::GetXULPrefSize(aState);  
+  DISPLAY_PREF_SIZE(this, size);
+
+  // guarantee that our preferred height doesn't exceed the standard
+  // listbox row height
+  size.height = std::max(mRect.height, size.height);
+  return size;
+}
+
+void
+nsListItemFrame::BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                             const nsRect&           aDirtyRect,
+                                             const nsDisplayListSet& aLists)
+{
+  if (aBuilder->IsForEventDelivery()) {
+    if (!mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::allowevents,
+                               nsGkAtoms::_true, eCaseMatters))
+      return;
+  }
+  
+  nsGridRowLeafFrame::BuildDisplayListForChildren(aBuilder, aDirtyRect, aLists);
+}
+
+// Creation Routine ///////////////////////////////////////////////////////////////////////
+
+already_AddRefed<nsBoxLayout> NS_NewGridRowLeafLayout();
+
+nsIFrame*
+NS_NewListItemFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  nsCOMPtr<nsBoxLayout> layout = NS_NewGridRowLeafLayout();
+  if (!layout) {
+    return nullptr;
+  }
+  
+  return new (aPresShell) nsListItemFrame(aContext, false, layout);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsListItemFrame)
diff --git a/layout/xul/nsListItemFrame.h b/layout/xul/nsListItemFrame.h
new file mode 100644
index 0000000000..40e731efa5
--- /dev/null
+++ b/layout/xul/nsListItemFrame.h
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+#include "nsGridRowLeafFrame.h"
+
+nsIFrame* NS_NewListItemFrame(nsIPresShell* aPresShell,
+                              nsStyleContext *aContext);
+
+class nsListItemFrame : public nsGridRowLeafFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewListItemFrame(nsIPresShell* aPresShell,
+                                       nsStyleContext *aContext);
+
+  // overridden so that children of listitems don't handle mouse events,
+  // unless allowevents="true" is specified on the listitem
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) override;
+
+  virtual nsSize GetXULPrefSize(nsBoxLayoutState& aState) override;
+
+protected:
+  explicit nsListItemFrame(nsStyleContext *aContext,
+                           bool aIsRoot = false,
+                           nsBoxLayout* aLayoutManager = nullptr);
+  virtual ~nsListItemFrame();
+
+}; // class nsListItemFrame
diff --git a/layout/xul/nsMenuBarFrame.cpp b/layout/xul/nsMenuBarFrame.cpp
new file mode 100644
index 0000000000..80aa98fbd7
--- /dev/null
+++ b/layout/xul/nsMenuBarFrame.cpp
@@ -0,0 +1,434 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMenuBarFrame.h"
+#include "nsIServiceManager.h"
+#include "nsIContent.h"
+#include "nsIAtom.h"
+#include "nsPresContext.h"
+#include "nsStyleContext.h"
+#include "nsCSSRendering.h"
+#include "nsNameSpaceManager.h"
+#include "nsIDocument.h"
+#include "nsGkAtoms.h"
+#include "nsMenuFrame.h"
+#include "nsMenuPopupFrame.h"
+#include "nsUnicharUtils.h"
+#include "nsPIDOMWindow.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsCSSFrameConstructor.h"
+#ifdef XP_WIN
+#include "nsISound.h"
+#include "nsWidgetsCID.h"
+#endif
+#include "nsContentUtils.h"
+#include "nsUTF8Utils.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/dom/Event.h"
+
+using namespace mozilla;
+
+//
+// NS_NewMenuBarFrame
+//
+// Wrapper for creating a new menu Bar container
+//
+nsIFrame*
+NS_NewMenuBarFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsMenuBarFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsMenuBarFrame)
+
+NS_QUERYFRAME_HEAD(nsMenuBarFrame)
+  NS_QUERYFRAME_ENTRY(nsMenuBarFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsBoxFrame)
+
+//
+// nsMenuBarFrame cntr
+//
+nsMenuBarFrame::nsMenuBarFrame(nsStyleContext* aContext):
+  nsBoxFrame(aContext),
+    mStayActive(false),
+    mIsActive(false),
+    mCurrentMenu(nullptr),
+    mTarget(nullptr)
+{
+} // cntr
+
+void
+nsMenuBarFrame::Init(nsIContent*       aContent,
+                     nsContainerFrame* aParent,
+                     nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  // Create the menu bar listener.
+  mMenuBarListener = new nsMenuBarListener(this);
+
+  // Hook up the menu bar as a key listener on the whole document.  It will see every
+  // key press that occurs, but after everyone else does.
+  mTarget = aContent->GetComposedDoc();
+
+  // Also hook up the listener to the window listening for focus events. This is so we can keep proper
+  // state as the user alt-tabs through processes.
+
+  mTarget->AddSystemEventListener(NS_LITERAL_STRING("keypress"), mMenuBarListener, false);
+  mTarget->AddSystemEventListener(NS_LITERAL_STRING("keydown"), mMenuBarListener, false);
+  mTarget->AddSystemEventListener(NS_LITERAL_STRING("keyup"), mMenuBarListener, false);
+  mTarget->AddSystemEventListener(NS_LITERAL_STRING("mozaccesskeynotfound"), mMenuBarListener, false);
+
+  // mousedown event should be handled in all phase
+  mTarget->AddEventListener(NS_LITERAL_STRING("mousedown"), mMenuBarListener, true);
+  mTarget->AddEventListener(NS_LITERAL_STRING("mousedown"), mMenuBarListener, false);
+  mTarget->AddEventListener(NS_LITERAL_STRING("blur"), mMenuBarListener, true);
+
+  mTarget->AddEventListener(NS_LITERAL_STRING("MozDOMFullscreen:Entered"), mMenuBarListener, false);
+}
+
+NS_IMETHODIMP
+nsMenuBarFrame::SetActive(bool aActiveFlag)
+{
+  // If the activity is not changed, there is nothing to do.
+  if (mIsActive == aActiveFlag)
+    return NS_OK;
+
+  if (!aActiveFlag) {
+    // Don't deactivate when switching between menus on the menubar.
+    if (mStayActive)
+      return NS_OK;
+
+    // if there is a request to deactivate the menu bar, check to see whether
+    // there is a menu popup open for the menu bar. In this case, don't
+    // deactivate the menu bar.
+    nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+    if (pm && pm->IsPopupOpenForMenuParent(this))
+      return NS_OK;
+  }
+
+  mIsActive = aActiveFlag;
+  if (mIsActive) {
+    InstallKeyboardNavigator();
+  }
+  else {
+    mActiveByKeyboard = false;
+    RemoveKeyboardNavigator();
+  }
+
+  NS_NAMED_LITERAL_STRING(active, "DOMMenuBarActive");
+  NS_NAMED_LITERAL_STRING(inactive, "DOMMenuBarInactive");
+  
+  FireDOMEvent(mIsActive ? active : inactive, mContent);
+
+  return NS_OK;
+}
+
+nsMenuFrame*
+nsMenuBarFrame::ToggleMenuActiveState()
+{
+  if (mIsActive) {
+    // Deactivate the menu bar
+    SetActive(false);
+    if (mCurrentMenu) {
+      nsMenuFrame* closeframe = mCurrentMenu;
+      closeframe->SelectMenu(false);
+      mCurrentMenu = nullptr;
+      return closeframe;
+    }
+  }
+  else {
+    // if the menu bar is already selected (eg. mouseover), deselect it
+    if (mCurrentMenu)
+      mCurrentMenu->SelectMenu(false);
+
+    // Set the active menu to be the top left item (e.g., the File menu).
+    // We use an attribute called "menuactive" to track the current 
+    // active menu.
+    nsMenuFrame* firstFrame = nsXULPopupManager::GetNextMenuItem(this, nullptr, false);
+    if (firstFrame) {
+      // Activate the menu bar
+      SetActive(true);
+      firstFrame->SelectMenu(true);
+      
+      // Track this item for keyboard navigation.
+      mCurrentMenu = firstFrame;
+    }
+  }
+
+  return nullptr;
+}
+
+nsMenuFrame*
+nsMenuBarFrame::FindMenuWithShortcut(nsIDOMKeyEvent* aKeyEvent)
+{
+  uint32_t charCode;
+  aKeyEvent->GetCharCode(&charCode);
+
+  AutoTArray<uint32_t, 10> accessKeys;
+  WidgetKeyboardEvent* nativeKeyEvent =
+    aKeyEvent->AsEvent()->WidgetEventPtr()->AsKeyboardEvent();
+  if (nativeKeyEvent) {
+    nativeKeyEvent->GetAccessKeyCandidates(accessKeys);
+  }
+  if (accessKeys.IsEmpty() && charCode)
+    accessKeys.AppendElement(charCode);
+
+  if (accessKeys.IsEmpty())
+    return nullptr; // no character was pressed so just return
+
+  // Enumerate over our list of frames.
+  auto insertion = PresContext()->PresShell()->FrameConstructor()->
+    GetInsertionPoint(GetContent(), nullptr);
+  nsContainerFrame* immediateParent = insertion.mParentFrame;
+  if (!immediateParent)
+    immediateParent = this;
+
+  // Find a most preferred accesskey which should be returned.
+  nsIFrame* foundMenu = nullptr;
+  size_t foundIndex = accessKeys.NoIndex;
+  nsIFrame* currFrame = immediateParent->PrincipalChildList().FirstChild();
+
+  while (currFrame) {
+    nsIContent* current = currFrame->GetContent();
+
+    // See if it's a menu item.
+    if (nsXULPopupManager::IsValidMenuItem(current, false)) {
+      // Get the shortcut attribute.
+      nsAutoString shortcutKey;
+      current->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, shortcutKey);
+      if (!shortcutKey.IsEmpty()) {
+        ToLowerCase(shortcutKey);
+        const char16_t* start = shortcutKey.BeginReading();
+        const char16_t* end = shortcutKey.EndReading();
+        uint32_t ch = UTF16CharEnumerator::NextChar(&start, end);
+        size_t index = accessKeys.IndexOf(ch);
+        if (index != accessKeys.NoIndex &&
+            (foundIndex == accessKeys.NoIndex || index < foundIndex)) {
+          foundMenu = currFrame;
+          foundIndex = index;
+        }
+      }
+    }
+    currFrame = currFrame->GetNextSibling();
+  }
+  if (foundMenu) {
+    return do_QueryFrame(foundMenu);
+  }
+
+  // didn't find a matching menu item
+#ifdef XP_WIN
+  // behavior on Windows - this item is on the menu bar, beep and deactivate the menu bar
+  if (mIsActive) {
+    nsCOMPtr<nsISound> soundInterface = do_CreateInstance("@mozilla.org/sound;1");
+    if (soundInterface)
+      soundInterface->Beep();
+  }
+
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm) {
+    nsIFrame* popup = pm->GetTopPopup(ePopupTypeAny);
+    if (popup)
+      pm->HidePopup(popup->GetContent(), true, true, true, false);
+  }
+
+  SetCurrentMenuItem(nullptr);
+  SetActive(false);
+
+#endif  // #ifdef XP_WIN
+
+  return nullptr;
+}
+
+/* virtual */ nsMenuFrame*
+nsMenuBarFrame::GetCurrentMenuItem()
+{
+  return mCurrentMenu;
+}
+
+NS_IMETHODIMP
+nsMenuBarFrame::SetCurrentMenuItem(nsMenuFrame* aMenuItem)
+{
+  if (mCurrentMenu == aMenuItem)
+    return NS_OK;
+
+  if (mCurrentMenu)
+    mCurrentMenu->SelectMenu(false);
+
+  if (aMenuItem)
+    aMenuItem->SelectMenu(true);
+
+  mCurrentMenu = aMenuItem;
+
+  return NS_OK;
+}
+
+void
+nsMenuBarFrame::CurrentMenuIsBeingDestroyed()
+{
+  mCurrentMenu->SelectMenu(false);
+  mCurrentMenu = nullptr;
+}
+
+class nsMenuBarSwitchMenu : public Runnable
+{
+public:
+  nsMenuBarSwitchMenu(nsIContent* aMenuBar,
+                      nsIContent *aOldMenu,
+                      nsIContent *aNewMenu,
+                      bool aSelectFirstItem)
+    : mMenuBar(aMenuBar), mOldMenu(aOldMenu), mNewMenu(aNewMenu),
+      mSelectFirstItem(aSelectFirstItem)
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+    if (!pm)
+      return NS_ERROR_UNEXPECTED;
+
+    // if switching from one menu to another, set a flag so that the call to
+    // HidePopup doesn't deactivate the menubar when the first menu closes.
+    nsMenuBarFrame* menubar = nullptr;
+    if (mOldMenu && mNewMenu) {
+      menubar = do_QueryFrame(mMenuBar->GetPrimaryFrame());
+      if (menubar)
+        menubar->SetStayActive(true);
+    }
+
+    if (mOldMenu) {
+      nsWeakFrame weakMenuBar(menubar);
+      pm->HidePopup(mOldMenu, false, false, false, false);
+      // clear the flag again
+      if (mNewMenu && weakMenuBar.IsAlive())
+        menubar->SetStayActive(false);
+    }
+
+    if (mNewMenu)
+      pm->ShowMenu(mNewMenu, mSelectFirstItem, false);
+
+    return NS_OK;
+  }
+
+private:
+  nsCOMPtr<nsIContent> mMenuBar;
+  nsCOMPtr<nsIContent> mOldMenu;
+  nsCOMPtr<nsIContent> mNewMenu;
+  bool mSelectFirstItem;
+};
+
+NS_IMETHODIMP
+nsMenuBarFrame::ChangeMenuItem(nsMenuFrame* aMenuItem,
+                               bool aSelectFirstItem,
+                               bool aFromKey)
+{
+  if (mCurrentMenu == aMenuItem)
+    return NS_OK;
+
+  // check if there's an open context menu, we ignore this
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm && pm->HasContextMenu(nullptr))
+    return NS_OK;
+
+  nsIContent* aOldMenu = nullptr;
+  nsIContent* aNewMenu = nullptr;
+  
+  // Unset the current child.
+  bool wasOpen = false;
+  if (mCurrentMenu) {
+    wasOpen = mCurrentMenu->IsOpen();
+    mCurrentMenu->SelectMenu(false);
+    if (wasOpen) {
+      nsMenuPopupFrame* popupFrame = mCurrentMenu->GetPopup();
+      if (popupFrame)
+        aOldMenu = popupFrame->GetContent();
+    }
+  }
+
+  // set to null first in case the IsAlive check below returns false
+  mCurrentMenu = nullptr;
+
+  // Set the new child.
+  if (aMenuItem) {
+    nsCOMPtr<nsIContent> content = aMenuItem->GetContent();
+    aMenuItem->SelectMenu(true);
+    mCurrentMenu = aMenuItem;
+    if (wasOpen && !aMenuItem->IsDisabled())
+      aNewMenu = content;
+  }
+
+  // use an event so that hiding and showing can be done synchronously, which
+  // avoids flickering
+  nsCOMPtr<nsIRunnable> event =
+    new nsMenuBarSwitchMenu(GetContent(), aOldMenu, aNewMenu, aSelectFirstItem);
+  return NS_DispatchToCurrentThread(event);
+}
+
+nsMenuFrame*
+nsMenuBarFrame::Enter(WidgetGUIEvent* aEvent)
+{
+  if (!mCurrentMenu)
+    return nullptr;
+
+  if (mCurrentMenu->IsOpen())
+    return mCurrentMenu->Enter(aEvent);
+
+  return mCurrentMenu;
+}
+
+bool
+nsMenuBarFrame::MenuClosed()
+{
+  SetActive(false);
+  if (!mIsActive && mCurrentMenu) {
+    mCurrentMenu->SelectMenu(false);
+    mCurrentMenu = nullptr;
+    return true;
+  }
+  return false;
+}
+
+void
+nsMenuBarFrame::InstallKeyboardNavigator()
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm)
+    pm->SetActiveMenuBar(this, true);
+}
+
+void
+nsMenuBarFrame::RemoveKeyboardNavigator()
+{
+  if (!mIsActive) {
+    nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+    if (pm)
+      pm->SetActiveMenuBar(this, false);
+  }
+}
+
+void
+nsMenuBarFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm)
+    pm->SetActiveMenuBar(this, false);
+
+  mTarget->RemoveSystemEventListener(NS_LITERAL_STRING("keypress"), mMenuBarListener, false);
+  mTarget->RemoveSystemEventListener(NS_LITERAL_STRING("keydown"), mMenuBarListener, false);
+  mTarget->RemoveSystemEventListener(NS_LITERAL_STRING("keyup"), mMenuBarListener, false);
+  mTarget->RemoveSystemEventListener(NS_LITERAL_STRING("mozaccesskeynotfound"), mMenuBarListener, false);
+
+  mTarget->RemoveEventListener(NS_LITERAL_STRING("mousedown"), mMenuBarListener, true);
+  mTarget->RemoveEventListener(NS_LITERAL_STRING("mousedown"), mMenuBarListener, false);
+  mTarget->RemoveEventListener(NS_LITERAL_STRING("blur"), mMenuBarListener, true);
+
+  mTarget->RemoveEventListener(NS_LITERAL_STRING("MozDOMFullscreen:Entered"), mMenuBarListener, false);
+
+  mMenuBarListener->OnDestroyMenuBarFrame();
+  mMenuBarListener = nullptr;
+
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
diff --git a/layout/xul/nsMenuBarFrame.h b/layout/xul/nsMenuBarFrame.h
new file mode 100644
index 0000000000..676463c50e
--- /dev/null
+++ b/layout/xul/nsMenuBarFrame.h
@@ -0,0 +1,125 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// nsMenuBarFrame
+//
+
+#ifndef nsMenuBarFrame_h__
+#define nsMenuBarFrame_h__
+
+#include "mozilla/Attributes.h"
+#include "nsIAtom.h"
+#include "nsCOMPtr.h"
+#include "nsBoxFrame.h"
+#include "nsMenuFrame.h"
+#include "nsMenuBarListener.h"
+#include "nsMenuParent.h"
+
+class nsIContent;
+
+nsIFrame* NS_NewMenuBarFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+class nsMenuBarFrame final : public nsBoxFrame, public nsMenuParent
+{
+public:
+  NS_DECL_QUERYFRAME_TARGET(nsMenuBarFrame)
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  explicit nsMenuBarFrame(nsStyleContext* aContext);
+
+  // nsMenuParent interface
+  virtual nsMenuFrame* GetCurrentMenuItem() override;
+  NS_IMETHOD SetCurrentMenuItem(nsMenuFrame* aMenuItem) override;
+  virtual void CurrentMenuIsBeingDestroyed() override;
+  NS_IMETHOD ChangeMenuItem(nsMenuFrame* aMenuItem,
+                            bool aSelectFirstItem,
+                            bool aFromKey) override;
+
+  NS_IMETHOD SetActive(bool aActiveFlag) override; 
+
+  virtual bool IsMenuBar() override { return true; }
+  virtual bool IsContextMenu() override { return false; }
+  virtual bool IsActive() override { return mIsActive; }
+  virtual bool IsMenu() override { return false; }
+  virtual bool IsOpen() override { return true; } // menubars are considered always open
+
+  bool IsMenuOpen() { return mCurrentMenu && mCurrentMenu->IsOpen(); }
+
+  void InstallKeyboardNavigator();
+  void RemoveKeyboardNavigator();
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual void LockMenuUntilClosed(bool aLock) override {}
+  virtual bool IsMenuLocked() override { return false; }
+
+// Non-interface helpers
+
+  // The 'stay active' flag is set when navigating from one top-level menu
+  // to another, to prevent the menubar from deactivating and submenus from
+  // firing extra DOMMenuItemActive events.
+  bool GetStayActive() { return mStayActive; }
+  void SetStayActive(bool aStayActive) { mStayActive = aStayActive; }
+
+  // Called when a menu on the menu bar is clicked on. Returns a menu if one
+  // needs to be closed.
+  nsMenuFrame* ToggleMenuActiveState();
+
+  bool IsActiveByKeyboard() { return mActiveByKeyboard; }
+  void SetActiveByKeyboard() { mActiveByKeyboard = true; }
+
+  // indicate that a menu on the menubar was closed. Returns true if the caller
+  // may deselect the menuitem.
+  virtual bool MenuClosed() override;
+
+  // Called when Enter is pressed while the menubar is focused. If the current
+  // menu is open, let the child handle the key.
+  nsMenuFrame* Enter(mozilla::WidgetGUIEvent* aEvent);
+
+  // Used to handle ALT+key combos
+  nsMenuFrame* FindMenuWithShortcut(nsIDOMKeyEvent* aKeyEvent);
+
+  virtual bool IsFrameOfType(uint32_t aFlags) const override
+  {
+    // Override bogus IsFrameOfType in nsBoxFrame.
+    if (aFlags & (nsIFrame::eReplacedContainsBlock | nsIFrame::eReplaced))
+      return false;
+    return nsBoxFrame::IsFrameOfType(aFlags);
+  }
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override
+  {
+      return MakeFrameName(NS_LITERAL_STRING("MenuBar"), aResult);
+  }
+#endif
+
+protected:
+  RefPtr<nsMenuBarListener> mMenuBarListener; // The listener that tells us about key and mouse events.
+
+  // flag that is temporarily set when switching from one menu on the menubar to another
+  // to indicate that the menubar should not be deactivated.
+  bool mStayActive;
+
+  bool mIsActive; // Whether or not the menu bar is active (a menu item is highlighted or shown).
+
+  // whether the menubar was made active via the keyboard.
+  bool mActiveByKeyboard;
+
+  // The current menu that is active (highlighted), which may not be open. This will
+  // be null if no menu is active.
+  nsMenuFrame* mCurrentMenu;
+
+  mozilla::dom::EventTarget* mTarget;
+
+}; // class nsMenuBarFrame
+
+#endif
diff --git a/layout/xul/nsMenuBarListener.cpp b/layout/xul/nsMenuBarListener.cpp
new file mode 100644
index 0000000000..0fce497b80
--- /dev/null
+++ b/layout/xul/nsMenuBarListener.cpp
@@ -0,0 +1,455 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMenuBarListener.h"
+#include "nsMenuBarFrame.h"
+#include "nsMenuPopupFrame.h"
+#include "nsIDOMEvent.h"
+
+// Drag & Drop, Clipboard
+#include "nsIServiceManager.h"
+#include "nsWidgetsCID.h"
+#include "nsCOMPtr.h"
+#include "nsIDOMKeyEvent.h"
+#include "nsIContent.h"
+#include "nsIDOMNode.h"
+#include "nsIDOMElement.h"
+
+#include "nsContentUtils.h"
+#include "mozilla/BasicEvents.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/TextEvents.h"
+
+using namespace mozilla;
+
+/*
+ * nsMenuBarListener implementation
+ */
+
+NS_IMPL_ISUPPORTS(nsMenuBarListener, nsIDOMEventListener)
+
+////////////////////////////////////////////////////////////////////////
+
+int32_t nsMenuBarListener::mAccessKey = -1;
+Modifiers nsMenuBarListener::mAccessKeyMask = 0;
+bool nsMenuBarListener::mAccessKeyFocuses = false;
+
+nsMenuBarListener::nsMenuBarListener(nsMenuBarFrame* aMenuBar) 
+  :mAccessKeyDown(false), mAccessKeyDownCanceled(false)
+{
+  mMenuBarFrame = aMenuBar;
+}
+
+////////////////////////////////////////////////////////////////////////
+nsMenuBarListener::~nsMenuBarListener() 
+{
+}
+
+void
+nsMenuBarListener::OnDestroyMenuBarFrame()
+{
+  mMenuBarFrame = nullptr;
+}
+
+void
+nsMenuBarListener::InitializeStatics()
+{
+  Preferences::AddBoolVarCache(&mAccessKeyFocuses,
+                               "ui.key.menuAccessKeyFocuses");
+}
+
+nsresult
+nsMenuBarListener::GetMenuAccessKey(int32_t* aAccessKey)
+{
+  if (!aAccessKey)
+    return NS_ERROR_INVALID_POINTER;
+  InitAccessKey();
+  *aAccessKey = mAccessKey;
+  return NS_OK;
+}
+
+void nsMenuBarListener::InitAccessKey()
+{
+  if (mAccessKey >= 0)
+    return;
+
+  // Compiled-in defaults, in case we can't get LookAndFeel --
+  // mac doesn't have menu shortcuts, other platforms use alt.
+#ifdef XP_MACOSX
+  mAccessKey = 0;
+  mAccessKeyMask = 0;
+#else
+  mAccessKey = nsIDOMKeyEvent::DOM_VK_ALT;
+  mAccessKeyMask = MODIFIER_ALT;
+#endif
+
+  // Get the menu access key value from prefs, overriding the default:
+  mAccessKey = Preferences::GetInt("ui.key.menuAccessKey", mAccessKey);
+  if (mAccessKey == nsIDOMKeyEvent::DOM_VK_SHIFT)
+    mAccessKeyMask = MODIFIER_SHIFT;
+  else if (mAccessKey == nsIDOMKeyEvent::DOM_VK_CONTROL)
+    mAccessKeyMask = MODIFIER_CONTROL;
+  else if (mAccessKey == nsIDOMKeyEvent::DOM_VK_ALT)
+    mAccessKeyMask = MODIFIER_ALT;
+  else if (mAccessKey == nsIDOMKeyEvent::DOM_VK_META)
+    mAccessKeyMask = MODIFIER_META;
+  else if (mAccessKey == nsIDOMKeyEvent::DOM_VK_WIN)
+    mAccessKeyMask = MODIFIER_OS;
+}
+
+void
+nsMenuBarListener::ToggleMenuActiveState()
+{
+  nsMenuFrame* closemenu = mMenuBarFrame->ToggleMenuActiveState();
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm && closemenu) {
+    nsMenuPopupFrame* popupFrame = closemenu->GetPopup();
+    if (popupFrame)
+      pm->HidePopup(popupFrame->GetContent(), false, false, true, false);
+  }
+}
+
+////////////////////////////////////////////////////////////////////////
+nsresult
+nsMenuBarListener::KeyUp(nsIDOMEvent* aKeyEvent)
+{  
+  nsCOMPtr<nsIDOMKeyEvent> keyEvent = do_QueryInterface(aKeyEvent);
+  if (!keyEvent) {
+    return NS_OK;
+  }
+
+  InitAccessKey();
+
+  //handlers shouldn't be triggered by non-trusted events.
+  bool trustedEvent = false;
+  aKeyEvent->GetIsTrusted(&trustedEvent);
+
+  if (!trustedEvent) {
+    return NS_OK;
+  }
+
+  if (mAccessKey && mAccessKeyFocuses)
+  {
+    bool defaultPrevented = false;
+    aKeyEvent->GetDefaultPrevented(&defaultPrevented);
+
+    // On a press of the ALT key by itself, we toggle the menu's 
+    // active/inactive state.
+    // Get the ascii key code.
+    uint32_t theChar;
+    keyEvent->GetKeyCode(&theChar);
+
+    if (!defaultPrevented && mAccessKeyDown && !mAccessKeyDownCanceled &&
+        (int32_t)theChar == mAccessKey)
+    {
+      // The access key was down and is now up, and no other
+      // keys were pressed in between.
+      bool toggleMenuActiveState = true;
+      if (!mMenuBarFrame->IsActive()) {
+        // First, close all existing popups because other popups shouldn't
+        // handle key events when menubar is active and IME should be
+        // disabled.
+        nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+        if (pm) {
+          pm->Rollup(0, false, nullptr, nullptr);
+        }
+        // If menubar active state is changed or the menubar is destroyed
+        // during closing the popups, we should do nothing anymore.
+        toggleMenuActiveState = !Destroyed() && !mMenuBarFrame->IsActive();
+      }
+      if (toggleMenuActiveState) {
+        if (!mMenuBarFrame->IsActive()) {
+          mMenuBarFrame->SetActiveByKeyboard();
+        }
+        ToggleMenuActiveState();
+      }
+    }
+    mAccessKeyDown = false;
+    mAccessKeyDownCanceled = false;
+
+    bool active = !Destroyed() && mMenuBarFrame->IsActive();
+    if (active) {
+      aKeyEvent->StopPropagation();
+      aKeyEvent->PreventDefault();
+      return NS_OK; // I am consuming event
+    }
+  }
+  
+  return NS_OK; // means I am NOT consuming event
+}
+
+////////////////////////////////////////////////////////////////////////
+nsresult
+nsMenuBarListener::KeyPress(nsIDOMEvent* aKeyEvent)
+{
+  // if event has already been handled, bail
+  if (aKeyEvent) {
+    bool eventHandled = false;
+    aKeyEvent->GetDefaultPrevented(&eventHandled);
+    if (eventHandled) {
+      return NS_OK;       // don't consume event
+    }
+  }
+
+  //handlers shouldn't be triggered by non-trusted events.
+  bool trustedEvent = false;
+  if (aKeyEvent) {
+    aKeyEvent->GetIsTrusted(&trustedEvent);
+  }
+
+  if (!trustedEvent) {
+    return NS_OK;
+  }
+
+  InitAccessKey();
+
+  if (mAccessKey)
+  {
+    // If accesskey handling was forwarded to a child process, wait for
+    // the mozaccesskeynotfound event before handling accesskeys.
+    WidgetKeyboardEvent* nativeKeyEvent =
+      aKeyEvent->WidgetEventPtr()->AsKeyboardEvent();
+    if (!nativeKeyEvent ||
+        (nativeKeyEvent && nativeKeyEvent->mAccessKeyForwardedToChild)) {
+      return NS_OK;
+    }
+
+    nsCOMPtr<nsIDOMKeyEvent> keyEvent = do_QueryInterface(aKeyEvent);
+    uint32_t keyCode, charCode;
+    keyEvent->GetKeyCode(&keyCode);
+    keyEvent->GetCharCode(&charCode);
+
+    bool hasAccessKeyCandidates = charCode != 0;
+    if (!hasAccessKeyCandidates) {
+      if (nativeKeyEvent) {
+        AutoTArray<uint32_t, 10> keys;
+        nativeKeyEvent->GetAccessKeyCandidates(keys);
+        hasAccessKeyCandidates = !keys.IsEmpty();
+      }
+    }
+
+    // Cancel the access key flag unless we are pressing the access key.
+    if (keyCode != (uint32_t)mAccessKey) {
+      mAccessKeyDownCanceled = true;
+    }
+
+    if (IsAccessKeyPressed(keyEvent) && hasAccessKeyCandidates) {
+      // Do shortcut navigation.
+      // A letter was pressed. We want to see if a shortcut gets matched. If
+      // so, we'll know the menu got activated.
+      nsMenuFrame* result = mMenuBarFrame->FindMenuWithShortcut(keyEvent);
+      if (result) {
+        mMenuBarFrame->SetActiveByKeyboard();
+        mMenuBarFrame->SetActive(true);
+        result->OpenMenu(true);
+
+        // The opened menu will listen next keyup event.
+        // Therefore, we should clear the keydown flags here.
+        mAccessKeyDown = mAccessKeyDownCanceled = false;
+
+        aKeyEvent->StopPropagation();
+        aKeyEvent->PreventDefault();
+      }
+    }    
+#ifndef XP_MACOSX
+    // Also need to handle F10 specially on Non-Mac platform.
+    else if (nativeKeyEvent->mMessage == eKeyPress && keyCode == NS_VK_F10) {
+      if ((GetModifiersForAccessKey(keyEvent) & ~MODIFIER_CONTROL) == 0) {
+        // The F10 key just went down by itself or with ctrl pressed.
+        // In Windows, both of these activate the menu bar.
+        mMenuBarFrame->SetActiveByKeyboard();
+        ToggleMenuActiveState();
+
+        if (mMenuBarFrame->IsActive()) {
+#ifdef MOZ_WIDGET_GTK
+          // In GTK, this also opens the first menu.
+          mMenuBarFrame->GetCurrentMenuItem()->OpenMenu(true);
+#endif
+          aKeyEvent->StopPropagation();
+          aKeyEvent->PreventDefault();
+        }
+      }
+    }
+#endif // !XP_MACOSX
+  }
+
+  return NS_OK;
+}
+
+bool
+nsMenuBarListener::IsAccessKeyPressed(nsIDOMKeyEvent* aKeyEvent)
+{
+  InitAccessKey();
+  // No other modifiers are allowed to be down except for Shift.
+  uint32_t modifiers = GetModifiersForAccessKey(aKeyEvent);
+
+  return (mAccessKeyMask != MODIFIER_SHIFT &&
+          (modifiers & mAccessKeyMask) &&
+          (modifiers & ~(mAccessKeyMask | MODIFIER_SHIFT)) == 0);
+}
+
+Modifiers
+nsMenuBarListener::GetModifiersForAccessKey(nsIDOMKeyEvent* aKeyEvent)
+{
+  WidgetInputEvent* inputEvent =
+    aKeyEvent->AsEvent()->WidgetEventPtr()->AsInputEvent();
+  MOZ_ASSERT(inputEvent);
+
+  static const Modifiers kPossibleModifiersForAccessKey =
+    (MODIFIER_SHIFT | MODIFIER_CONTROL | MODIFIER_ALT | MODIFIER_META |
+     MODIFIER_OS);
+  return (inputEvent->mModifiers & kPossibleModifiersForAccessKey);
+}
+
+////////////////////////////////////////////////////////////////////////
+nsresult
+nsMenuBarListener::KeyDown(nsIDOMEvent* aKeyEvent)
+{
+  InitAccessKey();
+
+  //handlers shouldn't be triggered by non-trusted events.
+  bool trustedEvent = false;
+  if (aKeyEvent) {
+    aKeyEvent->GetIsTrusted(&trustedEvent);
+  }
+
+  if (!trustedEvent)
+    return NS_OK;
+
+  if (mAccessKey && mAccessKeyFocuses)
+  {
+    bool defaultPrevented = false;
+    aKeyEvent->GetDefaultPrevented(&defaultPrevented);
+
+    nsCOMPtr<nsIDOMKeyEvent> keyEvent = do_QueryInterface(aKeyEvent);
+    uint32_t theChar;
+    keyEvent->GetKeyCode(&theChar);
+
+    // No other modifiers can be down.
+    // Especially CTRL.  CTRL+ALT == AltGR, and we'll fuck up on non-US
+    // enhanced 102-key keyboards if we don't check this.
+    bool isAccessKeyDownEvent =
+      ((theChar == (uint32_t)mAccessKey) &&
+       (GetModifiersForAccessKey(keyEvent) & ~mAccessKeyMask) == 0);
+
+    if (!mAccessKeyDown) {
+      // If accesskey isn't being pressed and the key isn't the accesskey,
+      // ignore the event.
+      if (!isAccessKeyDownEvent) {
+        return NS_OK;
+      }
+
+      // Otherwise, accept the accesskey state.
+      mAccessKeyDown = true;
+      // If default is prevented already, cancel the access key down.
+      mAccessKeyDownCanceled = defaultPrevented;
+      return NS_OK;
+    }
+
+    // If the pressed accesskey was canceled already or the event was
+    // consumed already, ignore the event.
+    if (mAccessKeyDownCanceled || defaultPrevented) {
+      return NS_OK;
+    }
+
+    // Some key other than the access key just went down,
+    // so we won't activate the menu bar when the access key is released.
+    mAccessKeyDownCanceled = !isAccessKeyDownEvent;
+  }
+
+  return NS_OK; // means I am NOT consuming event
+}
+
+////////////////////////////////////////////////////////////////////////
+
+nsresult
+nsMenuBarListener::Blur(nsIDOMEvent* aEvent)
+{
+  if (!mMenuBarFrame->IsMenuOpen() && mMenuBarFrame->IsActive()) {
+    ToggleMenuActiveState();
+  }
+  // Reset the accesskey state because we cannot receive the keyup event for
+  // the pressing accesskey.
+  mAccessKeyDown = false;
+  mAccessKeyDownCanceled = false;
+  return NS_OK; // means I am NOT consuming event
+}
+  
+////////////////////////////////////////////////////////////////////////
+nsresult 
+nsMenuBarListener::MouseDown(nsIDOMEvent* aMouseEvent)
+{
+  // NOTE: MouseDown method listens all phases
+
+  // Even if the mousedown event is canceled, it means the user don't want
+  // to activate the menu.  Therefore, we need to record it at capturing (or
+  // target) phase.
+  if (mAccessKeyDown) {
+    mAccessKeyDownCanceled = true;
+  }
+
+  uint16_t phase = 0;
+  nsresult rv = aMouseEvent->GetEventPhase(&phase);
+  NS_ENSURE_SUCCESS(rv, rv);
+  // Don't do anything at capturing phase, any behavior should be cancelable.
+  if (phase == nsIDOMEvent::CAPTURING_PHASE) {
+    return NS_OK;
+  }
+
+  if (!mMenuBarFrame->IsMenuOpen() && mMenuBarFrame->IsActive())
+    ToggleMenuActiveState();
+
+  return NS_OK; // means I am NOT consuming event
+}
+
+////////////////////////////////////////////////////////////////////////
+
+nsresult
+nsMenuBarListener::Fullscreen(nsIDOMEvent* aEvent)
+{
+  if (mMenuBarFrame->IsActive()) {
+    ToggleMenuActiveState();
+  }
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////
+nsresult
+nsMenuBarListener::HandleEvent(nsIDOMEvent* aEvent)
+{
+  // If the menu bar is collapsed, don't do anything.
+  if (!mMenuBarFrame->StyleVisibility()->IsVisible()) {
+    return NS_OK;
+  }
+
+  nsAutoString eventType;
+  aEvent->GetType(eventType);
+  
+  if (eventType.EqualsLiteral("keyup")) {
+    return KeyUp(aEvent);
+  }
+  if (eventType.EqualsLiteral("keydown")) {
+    return KeyDown(aEvent);
+  }
+  if (eventType.EqualsLiteral("keypress")) {
+    return KeyPress(aEvent);
+  }
+  if (eventType.EqualsLiteral("mozaccesskeynotfound")) {
+    return KeyPress(aEvent);
+  }
+  if (eventType.EqualsLiteral("blur")) {
+    return Blur(aEvent);
+  }
+  if (eventType.EqualsLiteral("mousedown")) {
+    return MouseDown(aEvent);
+  }
+  if (eventType.EqualsLiteral("MozDOMFullscreen:Entered")) {
+    return Fullscreen(aEvent);
+  }
+
+  NS_ABORT();
+
+  return NS_OK;
+}
diff --git a/layout/xul/nsMenuBarListener.h b/layout/xul/nsMenuBarListener.h
new file mode 100644
index 0000000000..3656c89e21
--- /dev/null
+++ b/layout/xul/nsMenuBarListener.h
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsMenuBarListener_h__
+#define nsMenuBarListener_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/EventForwards.h"
+#include "nsIDOMEventListener.h"
+
+// X.h defines KeyPress
+#ifdef KeyPress
+#undef KeyPress
+#endif
+
+class nsMenuBarFrame;
+class nsIDOMKeyEvent;
+
+/** editor Implementation of the DragListener interface
+ */
+class nsMenuBarListener final : public nsIDOMEventListener
+{
+public:
+  /** default constructor
+   */
+  explicit nsMenuBarListener(nsMenuBarFrame* aMenuBar);
+
+  static void InitializeStatics();
+   
+  NS_IMETHOD HandleEvent(nsIDOMEvent* aEvent) override;
+  
+  nsresult KeyUp(nsIDOMEvent* aMouseEvent);
+  nsresult KeyDown(nsIDOMEvent* aMouseEvent);
+  nsresult KeyPress(nsIDOMEvent* aMouseEvent);
+  nsresult Blur(nsIDOMEvent* aEvent);
+  nsresult MouseDown(nsIDOMEvent* aMouseEvent);
+  nsresult Fullscreen(nsIDOMEvent* aEvent);
+
+  static nsresult GetMenuAccessKey(int32_t* aAccessKey);
+  
+  NS_DECL_ISUPPORTS
+
+  static bool IsAccessKeyPressed(nsIDOMKeyEvent* event);
+
+  void OnDestroyMenuBarFrame();
+
+protected:
+  /** default destructor
+   */
+  virtual ~nsMenuBarListener();
+
+  static void InitAccessKey();
+
+  static mozilla::Modifiers GetModifiersForAccessKey(nsIDOMKeyEvent* event);
+
+  // This should only be called by the nsMenuBarListener during event dispatch,
+  // thus ensuring that this doesn't get destroyed during the process.
+  void ToggleMenuActiveState();
+
+  bool Destroyed() const { return !mMenuBarFrame; }
+
+  nsMenuBarFrame* mMenuBarFrame; // The menu bar object.
+  // Whether or not the ALT key is currently down.
+  bool mAccessKeyDown;
+  // Whether or not the ALT key down is canceled by other action.
+  bool mAccessKeyDownCanceled;
+  static bool mAccessKeyFocuses; // Does the access key by itself focus the menubar?
+  static int32_t mAccessKey;     // See nsIDOMKeyEvent.h for sample values
+  static mozilla::Modifiers mAccessKeyMask;// Modifier mask for the access key
+};
+
+
+#endif
diff --git a/layout/xul/nsMenuFrame.cpp b/layout/xul/nsMenuFrame.cpp
new file mode 100644
index 0000000000..ea968fab5a
--- /dev/null
+++ b/layout/xul/nsMenuFrame.cpp
@@ -0,0 +1,1514 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsGkAtoms.h"
+#include "nsHTMLParts.h"
+#include "nsMenuFrame.h"
+#include "nsBoxFrame.h"
+#include "nsIContent.h"
+#include "nsIAtom.h"
+#include "nsPresContext.h"
+#include "nsIPresShell.h"
+#include "nsStyleContext.h"
+#include "nsCSSRendering.h"
+#include "nsNameSpaceManager.h"
+#include "nsMenuPopupFrame.h"
+#include "nsMenuBarFrame.h"
+#include "nsIDocument.h"
+#include "nsIDOMElement.h"
+#include "nsIComponentManager.h"
+#include "nsBoxLayoutState.h"
+#include "nsIScrollableFrame.h"
+#include "nsBindingManager.h"
+#include "nsIServiceManager.h"
+#include "nsCSSFrameConstructor.h"
+#include "nsIDOMKeyEvent.h"
+#include "nsXPIDLString.h"
+#include "nsReadableUtils.h"
+#include "nsUnicharUtils.h"
+#include "nsIStringBundle.h"
+#include "nsContentUtils.h"
+#include "nsDisplayList.h"
+#include "nsIReflowCallback.h"
+#include "nsISound.h"
+#include "nsIDOMXULMenuListElement.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/EventStateManager.h"
+#include "mozilla/Likely.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h"
+#include <algorithm>
+
+using namespace mozilla;
+
+#define NS_MENU_POPUP_LIST_INDEX 0
+
+#if defined(XP_WIN)
+#define NSCONTEXTMENUISMOUSEUP 1
+#endif
+
+NS_DECLARE_FRAME_PROPERTY_FRAMELIST(PopupListProperty)
+
+// This global flag indicates that a menu just opened or closed and is used
+// to ignore the mousemove and mouseup events that would fire on the menu after
+// the mousedown occurred.
+static int32_t gMenuJustOpenedOrClosed = false;
+
+const int32_t kBlinkDelay = 67; // milliseconds
+
+// this class is used for dispatching menu activation events asynchronously.
+class nsMenuActivateEvent : public Runnable
+{
+public:
+  nsMenuActivateEvent(nsIContent *aMenu,
+                      nsPresContext* aPresContext,
+                      bool aIsActivate)
+    : mMenu(aMenu), mPresContext(aPresContext), mIsActivate(aIsActivate)
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    nsAutoString domEventToFire;
+
+    if (mIsActivate) {
+      // Highlight the menu.
+      mMenu->SetAttr(kNameSpaceID_None, nsGkAtoms::menuactive,
+                     NS_LITERAL_STRING("true"), true);
+      // The menuactivated event is used by accessibility to track the user's
+      // movements through menus
+      domEventToFire.AssignLiteral("DOMMenuItemActive");
+    }
+    else {
+      // Unhighlight the menu.
+      mMenu->UnsetAttr(kNameSpaceID_None, nsGkAtoms::menuactive, true);
+      domEventToFire.AssignLiteral("DOMMenuItemInactive");
+    }
+
+    RefPtr<Event> event = NS_NewDOMEvent(mMenu, mPresContext, nullptr);
+    event->InitEvent(domEventToFire, true, true);
+
+    event->SetTrusted(true);
+
+    EventDispatcher::DispatchDOMEvent(mMenu, nullptr, event,
+        mPresContext, nullptr);
+
+    return NS_OK;
+  }
+
+private:
+  nsCOMPtr<nsIContent> mMenu;
+  RefPtr<nsPresContext> mPresContext;
+  bool mIsActivate;
+};
+
+class nsMenuAttributeChangedEvent : public Runnable
+{
+public:
+  nsMenuAttributeChangedEvent(nsIFrame* aFrame, nsIAtom* aAttr)
+  : mFrame(aFrame), mAttr(aAttr)
+  {
+  }
+
+  NS_IMETHOD Run() override
+  {
+    nsMenuFrame* frame = static_cast<nsMenuFrame*>(mFrame.GetFrame());
+    NS_ENSURE_STATE(frame);
+    if (mAttr == nsGkAtoms::checked) {
+      frame->UpdateMenuSpecialState();
+    } else if (mAttr == nsGkAtoms::acceltext) {
+      // someone reset the accelText attribute,
+      // so clear the bit that says *we* set it
+      frame->RemoveStateBits(NS_STATE_ACCELTEXT_IS_DERIVED);
+      frame->BuildAcceleratorText(true);
+    }
+    else if (mAttr == nsGkAtoms::key) {
+      frame->BuildAcceleratorText(true);
+    } else if (mAttr == nsGkAtoms::type || mAttr == nsGkAtoms::name) {
+      frame->UpdateMenuType();
+    }
+    return NS_OK;
+  }
+protected:
+  nsWeakFrame       mFrame;
+  nsCOMPtr<nsIAtom> mAttr;
+};
+
+//
+// NS_NewMenuFrame and NS_NewMenuItemFrame
+//
+// Wrappers for creating a new menu popup container
+//
+nsIFrame*
+NS_NewMenuFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  nsMenuFrame* it = new (aPresShell) nsMenuFrame(aContext);
+  it->SetIsMenu(true);
+  return it;
+}
+
+nsIFrame*
+NS_NewMenuItemFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  nsMenuFrame* it = new (aPresShell) nsMenuFrame(aContext);
+  it->SetIsMenu(false);
+  return it;
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsMenuFrame)
+
+NS_QUERYFRAME_HEAD(nsMenuFrame)
+  NS_QUERYFRAME_ENTRY(nsMenuFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsBoxFrame)
+
+nsMenuFrame::nsMenuFrame(nsStyleContext* aContext):
+  nsBoxFrame(aContext),
+    mIsMenu(false),
+    mChecked(false),
+    mIgnoreAccelTextChange(false),
+    mType(eMenuType_Normal),
+    mBlinkState(0)
+{
+}
+
+nsMenuParent*
+nsMenuFrame::GetMenuParent() const
+{
+  nsContainerFrame* parent = GetParent();
+  for (; parent; parent = parent->GetParent()) {
+    nsMenuPopupFrame* popup = do_QueryFrame(parent);
+    if (popup) {
+      return popup;
+    }
+    nsMenuBarFrame* menubar = do_QueryFrame(parent);
+    if (menubar) {
+      return menubar;
+    }
+  }
+  return nullptr;
+}
+
+class nsASyncMenuInitialization final : public nsIReflowCallback
+{
+public:
+  explicit nsASyncMenuInitialization(nsIFrame* aFrame)
+    : mWeakFrame(aFrame)
+  {
+  }
+
+  virtual bool ReflowFinished() override
+  {
+    bool shouldFlush = false;
+    nsMenuFrame* menu = do_QueryFrame(mWeakFrame.GetFrame());
+    if (menu) {
+      menu->UpdateMenuType();
+      shouldFlush = true;
+    }
+    delete this;
+    return shouldFlush;
+  }
+
+  virtual void ReflowCallbackCanceled() override
+  {
+    delete this;
+  }
+
+  nsWeakFrame mWeakFrame;
+};
+
+void
+nsMenuFrame::Init(nsIContent*       aContent,
+                  nsContainerFrame* aParent,
+                  nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  // Set up a mediator which can be used for callbacks on this frame.
+  mTimerMediator = new nsMenuTimerMediator(this);
+
+  BuildAcceleratorText(false);
+  nsIReflowCallback* cb = new nsASyncMenuInitialization(this);
+  PresContext()->PresShell()->PostReflowCallback(cb);
+}
+
+const nsFrameList&
+nsMenuFrame::GetChildList(ChildListID aListID) const
+{
+  if (kPopupList == aListID) {
+    nsFrameList* list = GetPopupList();
+    return list ? *list : nsFrameList::EmptyList();
+  }
+  return nsBoxFrame::GetChildList(aListID);
+}
+
+void
+nsMenuFrame::GetChildLists(nsTArray<ChildList>* aLists) const
+{
+  nsBoxFrame::GetChildLists(aLists);
+  nsFrameList* list = GetPopupList();
+  if (list) {
+    list->AppendIfNonempty(aLists, kPopupList);
+  }
+}
+
+nsMenuPopupFrame*
+nsMenuFrame::GetPopup()
+{
+  nsFrameList* popupList = GetPopupList();
+  return popupList ? static_cast<nsMenuPopupFrame*>(popupList->FirstChild()) :
+                     nullptr;
+}
+
+nsFrameList*
+nsMenuFrame::GetPopupList() const
+{
+  if (!HasPopup()) {
+    return nullptr;
+  }
+  nsFrameList* prop = Properties().Get(PopupListProperty());
+  NS_ASSERTION(prop && prop->GetLength() == 1 &&
+               prop->FirstChild()->GetType() == nsGkAtoms::menuPopupFrame,
+               "popup list should have exactly one nsMenuPopupFrame");
+  return prop;
+}
+
+void
+nsMenuFrame::DestroyPopupList()
+{
+  NS_ASSERTION(HasPopup(), "huh?");
+  nsFrameList* prop = Properties().Remove(PopupListProperty());
+  NS_ASSERTION(prop && prop->IsEmpty(),
+               "popup list must exist and be empty when destroying");
+  RemoveStateBits(NS_STATE_MENU_HAS_POPUP_LIST);
+  prop->Delete(PresContext()->PresShell());
+}
+
+void
+nsMenuFrame::SetPopupFrame(nsFrameList& aFrameList)
+{
+  for (nsFrameList::Enumerator e(aFrameList); !e.AtEnd(); e.Next()) {
+    nsMenuPopupFrame* popupFrame = do_QueryFrame(e.get());
+    if (popupFrame) {
+      // Remove the frame from the list and store it in a nsFrameList* property.
+      aFrameList.RemoveFrame(popupFrame);
+      nsFrameList* popupList = new (PresContext()->PresShell()) nsFrameList(popupFrame, popupFrame);
+      Properties().Set(PopupListProperty(), popupList);
+      AddStateBits(NS_STATE_MENU_HAS_POPUP_LIST);
+      break;
+    }
+  }
+}
+
+void
+nsMenuFrame::SetInitialChildList(ChildListID     aListID,
+                                 nsFrameList&    aChildList)
+{
+  if (aListID == kPrincipalList || aListID == kPopupList) {
+    NS_ASSERTION(!HasPopup(), "SetInitialChildList called twice?");
+    SetPopupFrame(aChildList);
+  }
+  nsBoxFrame::SetInitialChildList(aListID, aChildList);
+}
+
+void
+nsMenuFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  // Kill our timer if one is active. This is not strictly necessary as
+  // the pointer to this frame will be cleared from the mediator, but
+  // this is done for added safety.
+  if (mOpenTimer) {
+    mOpenTimer->Cancel();
+  }
+
+  StopBlinking();
+
+  // Null out the pointer to this frame in the mediator wrapper so that it 
+  // doesn't try to interact with a deallocated frame.
+  mTimerMediator->ClearFrame();
+
+  // if the menu content is just being hidden, it may be made visible again
+  // later, so make sure to clear the highlighting.
+  mContent->UnsetAttr(kNameSpaceID_None, nsGkAtoms::menuactive, false);
+
+  // are we our menu parent's current menu item?
+  nsMenuParent* menuParent = GetMenuParent();
+  if (menuParent && menuParent->GetCurrentMenuItem() == this) {
+    // yes; tell it that we're going away
+    menuParent->CurrentMenuIsBeingDestroyed();
+  }
+
+  nsFrameList* popupList = GetPopupList();
+  if (popupList) {
+    popupList->DestroyFramesFrom(aDestructRoot);
+    DestroyPopupList();
+  }
+
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+void
+nsMenuFrame::BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                         const nsRect&           aDirtyRect,
+                                         const nsDisplayListSet& aLists)
+{
+  if (!aBuilder->IsForEventDelivery()) {
+    nsBoxFrame::BuildDisplayListForChildren(aBuilder, aDirtyRect, aLists);
+    return;
+  }
+    
+  nsDisplayListCollection set;
+  nsBoxFrame::BuildDisplayListForChildren(aBuilder, aDirtyRect, set);
+  
+  WrapListsInRedirector(aBuilder, set, aLists);
+}
+
+nsresult
+nsMenuFrame::HandleEvent(nsPresContext* aPresContext,
+                         WidgetGUIEvent* aEvent,
+                         nsEventStatus* aEventStatus)
+{
+  NS_ENSURE_ARG_POINTER(aEventStatus);
+  if (nsEventStatus_eConsumeNoDefault == *aEventStatus) {
+    return NS_OK;
+  }
+  nsMenuParent* menuParent = GetMenuParent();
+  if (menuParent && menuParent->IsMenuLocked()) {
+    return NS_OK;
+  }
+
+  nsWeakFrame weakFrame(this);
+  if (*aEventStatus == nsEventStatus_eIgnore)
+    *aEventStatus = nsEventStatus_eConsumeDoDefault;
+
+  // If a menu just opened, ignore the mouseup event that might occur after a
+  // the mousedown event that opened it. However, if a different mousedown
+  // event occurs, just clear this flag.
+  if (gMenuJustOpenedOrClosed) {
+    if (aEvent->mMessage == eMouseDown) {
+      gMenuJustOpenedOrClosed = false;
+    } else if (aEvent->mMessage == eMouseUp) {
+      return NS_OK;
+    }
+  }
+
+  bool onmenu = IsOnMenu();
+
+  if (aEvent->mMessage == eKeyPress && !IsDisabled()) {
+    WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
+    uint32_t keyCode = keyEvent->mKeyCode;
+#ifdef XP_MACOSX
+    // On mac, open menulist on either up/down arrow or space (w/o Cmd pressed)
+    if (!IsOpen() && ((keyEvent->mCharCode == ' ' && !keyEvent->IsMeta()) ||
+        (keyCode == NS_VK_UP || keyCode == NS_VK_DOWN))) {
+
+      // When pressing space, don't open the menu if performing an incremental search.
+      if (keyEvent->mCharCode != ' ' ||
+          !nsMenuPopupFrame::IsWithinIncrementalTime(keyEvent->mTime)) {
+        *aEventStatus = nsEventStatus_eConsumeNoDefault;
+        OpenMenu(false);
+      }
+    }
+#else
+    // On other platforms, toggle menulist on unmodified F4 or Alt arrow
+    if ((keyCode == NS_VK_F4 && !keyEvent->IsAlt()) ||
+        ((keyCode == NS_VK_UP || keyCode == NS_VK_DOWN) && keyEvent->IsAlt())) {
+      *aEventStatus = nsEventStatus_eConsumeNoDefault;
+      ToggleMenuState();
+    }
+#endif
+  }
+  else if (aEvent->mMessage == eMouseDown &&
+           aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton &&
+           !IsDisabled() && IsMenu()) {
+    // The menu item was selected. Bring up the menu.
+    // We have children.
+    // Don't prevent the default action here, since that will also cancel
+    // potential drag starts.
+    if (!menuParent || menuParent->IsMenuBar()) {
+      ToggleMenuState();
+    }
+    else {
+      if (!IsOpen()) {
+        menuParent->ChangeMenuItem(this, false, false);
+        OpenMenu(false);
+      }
+    }
+  }
+  else if (
+#ifndef NSCONTEXTMENUISMOUSEUP
+           (aEvent->mMessage == eMouseUp &&
+            aEvent->AsMouseEvent()->button == WidgetMouseEvent::eRightButton) &&
+#else
+           aEvent->mMessage == eContextMenu &&
+#endif
+           onmenu && !IsMenu() && !IsDisabled()) {
+    // if this menu is a context menu it accepts right-clicks...fire away!
+    // Make sure we cancel default processing of the context menu event so
+    // that it doesn't bubble and get seen again by the popuplistener and show
+    // another context menu.
+    //
+    // Furthermore (there's always more, isn't there?), on some platforms (win32
+    // being one of them) we get the context menu event on a mouse up while
+    // on others we get it on a mouse down. For the ones where we get it on a
+    // mouse down, we must continue listening for the right button up event to
+    // dismiss the menu.
+    if (menuParent->IsContextMenu()) {
+      *aEventStatus = nsEventStatus_eConsumeNoDefault;
+      Execute(aEvent);
+    }
+  }
+  else if (aEvent->mMessage == eMouseUp &&
+           aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton &&
+           !IsMenu() && !IsDisabled()) {
+    // Execute the execute event handler.
+    *aEventStatus = nsEventStatus_eConsumeNoDefault;
+    Execute(aEvent);
+  }
+  else if (aEvent->mMessage == eMouseOut) {
+    // Kill our timer if one is active.
+    if (mOpenTimer) {
+      mOpenTimer->Cancel();
+      mOpenTimer = nullptr;
+    }
+
+    // Deactivate the menu.
+    if (menuParent) {
+      bool onmenubar = menuParent->IsMenuBar();
+      if (!(onmenubar && menuParent->IsActive())) {
+        if (IsMenu() && !onmenubar && IsOpen()) {
+          // Submenus don't get closed up immediately.
+        }
+        else if (this == menuParent->GetCurrentMenuItem()
+#ifdef XP_WIN
+                 && GetParentMenuListType() == eNotMenuList
+#endif
+        ) {
+          menuParent->ChangeMenuItem(nullptr, false, false);
+        }
+      }
+    }
+  }
+  else if (aEvent->mMessage == eMouseMove &&
+           (onmenu || (menuParent && menuParent->IsMenuBar()))) {
+    if (gMenuJustOpenedOrClosed) {
+      gMenuJustOpenedOrClosed = false;
+      return NS_OK;
+    }
+
+    if (IsDisabled() && GetParentMenuListType() != eNotMenuList) {
+      return NS_OK;
+    }
+
+    // Let the menu parent know we're the new item.
+    menuParent->ChangeMenuItem(this, false, false);
+    NS_ENSURE_TRUE(weakFrame.IsAlive(), NS_OK);
+    NS_ENSURE_TRUE(menuParent, NS_OK);
+
+    // we need to check if we really became the current menu
+    // item or not
+    nsMenuFrame *realCurrentItem = menuParent->GetCurrentMenuItem();
+    if (realCurrentItem != this) {
+      // we didn't (presumably because a context menu was active)
+      return NS_OK;
+    }
+
+    // Hovering over a menu in a popup should open it without a need for a click.
+    // A timer is used so that it doesn't open if the user moves the mouse quickly
+    // past the menu. This conditional check ensures that only menus have this
+    // behaviour
+    if (!IsDisabled() && IsMenu() && !IsOpen() && !mOpenTimer && !menuParent->IsMenuBar()) {
+      int32_t menuDelay =
+        LookAndFeel::GetInt(LookAndFeel::eIntID_SubmenuDelay, 300); // ms
+
+      // We're a menu, we're built, we're closed, and no timer has been kicked off.
+      mOpenTimer = do_CreateInstance("@mozilla.org/timer;1");
+      mOpenTimer->InitWithCallback(mTimerMediator, menuDelay, nsITimer::TYPE_ONE_SHOT);
+    }
+  }
+  
+  return NS_OK;
+}
+
+void
+nsMenuFrame::ToggleMenuState()
+{
+  if (IsOpen())
+    CloseMenu(false);
+  else
+    OpenMenu(false);
+}
+
+void
+nsMenuFrame::PopupOpened()
+{
+  nsWeakFrame weakFrame(this);
+  mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::open,
+                    NS_LITERAL_STRING("true"), true);
+  if (!weakFrame.IsAlive())
+    return;
+
+  nsMenuParent* menuParent = GetMenuParent();
+  if (menuParent) {
+    menuParent->SetActive(true);
+    // Make sure the current menu which is being toggled on
+    // the menubar is highlighted
+    menuParent->SetCurrentMenuItem(this);
+  }
+}
+
+void
+nsMenuFrame::PopupClosed(bool aDeselectMenu)
+{
+  nsWeakFrame weakFrame(this);
+  nsContentUtils::AddScriptRunner(
+    new nsUnsetAttrRunnable(mContent, nsGkAtoms::open));
+  if (!weakFrame.IsAlive())
+    return;
+
+  // if the popup is for a menu on a menubar, inform menubar to deactivate
+  nsMenuParent* menuParent = GetMenuParent();
+  if (menuParent && menuParent->MenuClosed()) {
+    if (aDeselectMenu) {
+      SelectMenu(false);
+    } else {
+      // We are not deselecting the parent menu while closing the popup, so send
+      // a DOMMenuItemActive event to the menu to indicate that the menu is
+      // becoming active again.
+      nsMenuFrame *current = menuParent->GetCurrentMenuItem();
+      if (current) {
+        // However, if the menu is a descendant on a menubar, and the menubar
+        // has the 'stay active' flag set, it means that the menubar is switching
+        // to another toplevel menu entirely (for example from Edit to View), so
+        // don't fire the DOMMenuItemActive event or else we'll send extraneous
+        // events for submenus. nsMenuBarFrame::ChangeMenuItem has already deselected
+        // the old menu, so it doesn't need to happen again here, and the new
+        // menu can be selected right away.
+        nsIFrame* parent = current;
+        while (parent) {
+          nsMenuBarFrame* menubar = do_QueryFrame(parent);
+          if (menubar && menubar->GetStayActive())
+            return;
+
+          parent = parent->GetParent();
+        }
+
+        nsCOMPtr<nsIRunnable> event =
+          new nsMenuActivateEvent(current->GetContent(),
+                                  PresContext(), true);
+        NS_DispatchToCurrentThread(event);
+      }
+    }
+  }
+}
+
+NS_IMETHODIMP
+nsMenuFrame::SelectMenu(bool aActivateFlag)
+{
+  if (mContent) {
+    // When a menu opens a submenu, the mouse will often be moved onto a
+    // sibling before moving onto an item within the submenu, causing the
+    // parent to become deselected. We need to ensure that the parent menu
+    // is reselected when an item in the submenu is selected, so navigate up
+    // from the item to its popup, and then to the popup above that.
+    if (aActivateFlag) {
+      nsIFrame* parent = GetParent();
+      while (parent) {
+        nsMenuPopupFrame* menupopup = do_QueryFrame(parent);
+        if (menupopup) {
+          // a menu is always the direct parent of a menupopup
+          nsMenuFrame* menu = do_QueryFrame(menupopup->GetParent());
+          if (menu) {
+            // a popup however is not necessarily the direct parent of a menu
+            nsIFrame* popupParent = menu->GetParent();
+            while (popupParent) {
+              menupopup = do_QueryFrame(popupParent);
+              if (menupopup) {
+                menupopup->SetCurrentMenuItem(menu);
+                break;
+              }
+              popupParent = popupParent->GetParent();
+            }
+          }
+          break;
+        }
+        parent = parent->GetParent();
+      }
+    }
+
+    // cancel the close timer if selecting a menu within the popup to be closed
+    nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+    if (pm) {
+      nsMenuParent* menuParent = GetMenuParent();
+      pm->CancelMenuTimer(menuParent);
+    }
+
+    nsCOMPtr<nsIRunnable> event =
+      new nsMenuActivateEvent(mContent, PresContext(), aActivateFlag);
+    NS_DispatchToCurrentThread(event);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsMenuFrame::AttributeChanged(int32_t aNameSpaceID,
+                              nsIAtom* aAttribute,
+                              int32_t aModType)
+{
+  if (aAttribute == nsGkAtoms::acceltext && mIgnoreAccelTextChange) {
+    // Reset the flag so that only one change is ignored.
+    mIgnoreAccelTextChange = false;
+    return NS_OK;
+  }
+
+  if (aAttribute == nsGkAtoms::checked ||
+      aAttribute == nsGkAtoms::acceltext ||
+      aAttribute == nsGkAtoms::key ||
+      aAttribute == nsGkAtoms::type ||
+      aAttribute == nsGkAtoms::name) {
+    nsCOMPtr<nsIRunnable> event =
+      new nsMenuAttributeChangedEvent(this, aAttribute);
+    nsContentUtils::AddScriptRunner(event);
+  }
+  return NS_OK;
+}
+
+nsIContent*
+nsMenuFrame::GetAnchor()
+{
+  mozilla::dom::Element* anchor = nullptr;
+
+  nsAutoString id;
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::anchor, id);
+  if (!id.IsEmpty()) {
+    nsIDocument* doc = mContent->OwnerDoc();
+
+    anchor =
+      doc->GetAnonymousElementByAttribute(mContent, nsGkAtoms::anonid, id);
+    if (!anchor) {
+      anchor = doc->GetElementById(id);
+    }
+  }
+
+  // Always return the menu's content if the anchor wasn't set or wasn't found.
+  return anchor && anchor->GetPrimaryFrame() ? anchor : mContent;
+}
+
+void
+nsMenuFrame::OpenMenu(bool aSelectFirstItem)
+{
+  if (!mContent)
+    return;
+
+  gMenuJustOpenedOrClosed = true;
+
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm) {
+    pm->KillMenuTimer();
+    // This opens the menu asynchronously
+    pm->ShowMenu(mContent, aSelectFirstItem, true);
+  }
+}
+
+void
+nsMenuFrame::CloseMenu(bool aDeselectMenu)
+{
+  gMenuJustOpenedOrClosed = true;
+
+  // Close the menu asynchronously
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm && HasPopup())
+    pm->HidePopup(GetPopup()->GetContent(), false, aDeselectMenu, true, false);
+}
+
+bool
+nsMenuFrame::IsSizedToPopup(nsIContent* aContent, bool aRequireAlways)
+{
+  nsAutoString sizedToPopup;
+  aContent->GetAttr(kNameSpaceID_None, nsGkAtoms::sizetopopup, sizedToPopup);
+  return sizedToPopup.EqualsLiteral("always") ||
+         (!aRequireAlways && sizedToPopup.EqualsLiteral("pref"));
+}
+
+nsSize
+nsMenuFrame::GetXULMinSize(nsBoxLayoutState& aBoxLayoutState)
+{
+  nsSize size = nsBoxFrame::GetXULMinSize(aBoxLayoutState);
+  DISPLAY_MIN_SIZE(this, size);
+
+  if (IsSizedToPopup(mContent, true))
+    SizeToPopup(aBoxLayoutState, size);
+
+  return size;
+}
+
+NS_IMETHODIMP
+nsMenuFrame::DoXULLayout(nsBoxLayoutState& aState)
+{
+  // lay us out
+  nsresult rv = nsBoxFrame::DoXULLayout(aState);
+
+  nsMenuPopupFrame* popupFrame = GetPopup();
+  if (popupFrame) {
+    bool sizeToPopup = IsSizedToPopup(mContent, false);
+    popupFrame->LayoutPopup(aState, this, GetAnchor()->GetPrimaryFrame(), sizeToPopup);
+  }
+
+  return rv;
+}
+
+#ifdef DEBUG_LAYOUT
+nsresult
+nsMenuFrame::SetXULDebug(nsBoxLayoutState& aState, bool aDebug)
+{
+  // see if our state matches the given debug state
+  bool debugSet = mState & NS_STATE_CURRENTLY_IN_DEBUG;
+  bool debugChanged = (!aDebug && debugSet) || (aDebug && !debugSet);
+
+  // if it doesn't then tell each child below us the new debug state
+  if (debugChanged)
+  {
+      nsBoxFrame::SetXULDebug(aState, aDebug);
+      nsMenuPopupFrame* popupFrame = GetPopup();
+      if (popupFrame)
+        SetXULDebug(aState, popupFrame, aDebug);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsMenuFrame::SetXULDebug(nsBoxLayoutState& aState, nsIFrame* aList, bool aDebug)
+{
+      if (!aList)
+          return NS_OK;
+
+      while (aList) {
+        if (aList->IsXULBoxFrame())
+          aList->SetXULDebug(aState, aDebug);
+
+        aList = aList->GetNextSibling();
+      }
+
+      return NS_OK;
+}
+#endif
+
+//
+// Enter
+//
+// Called when the user hits the <Enter>/<Return> keys or presses the
+// shortcut key. If this is a leaf item, the item's action will be executed.
+// In either case, do nothing if the item is disabled.
+//
+nsMenuFrame*
+nsMenuFrame::Enter(WidgetGUIEvent* aEvent)
+{
+  if (IsDisabled()) {
+#ifdef XP_WIN
+    // behavior on Windows - close the popup chain
+    nsMenuParent* menuParent = GetMenuParent();
+    if (menuParent) {
+      nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+      if (pm) {
+        nsIFrame* popup = pm->GetTopPopup(ePopupTypeAny);
+        if (popup)
+          pm->HidePopup(popup->GetContent(), true, true, true, false);
+      }
+    }
+#endif   // #ifdef XP_WIN
+    // this menu item was disabled - exit
+    return nullptr;
+  }
+
+  if (!IsOpen()) {
+    // The enter key press applies to us.
+    nsMenuParent* menuParent = GetMenuParent();
+    if (!IsMenu() && menuParent)
+      Execute(aEvent);          // Execute our event handler
+    else
+      return this;
+  }
+
+  return nullptr;
+}
+
+bool
+nsMenuFrame::IsOpen()
+{
+  nsMenuPopupFrame* popupFrame = GetPopup();
+  return popupFrame && popupFrame->IsOpen();
+}
+
+bool
+nsMenuFrame::IsMenu()
+{
+  return mIsMenu;
+}
+
+nsMenuListType
+nsMenuFrame::GetParentMenuListType()
+{
+  nsMenuParent* menuParent = GetMenuParent();
+  if (menuParent && menuParent->IsMenu()) {
+    nsMenuPopupFrame* popupFrame = static_cast<nsMenuPopupFrame*>(menuParent);
+    nsIFrame* parentMenu = popupFrame->GetParent();
+    if (parentMenu) {
+      nsCOMPtr<nsIDOMXULMenuListElement> menulist = do_QueryInterface(parentMenu->GetContent());
+      if (menulist) {
+        bool isEditable = false;
+        menulist->GetEditable(&isEditable);
+        return isEditable ? eEditableMenuList : eReadonlyMenuList;
+      }
+    }
+  }
+  return eNotMenuList;
+}
+
+nsresult
+nsMenuFrame::Notify(nsITimer* aTimer)
+{
+  // Our timer has fired.
+  if (aTimer == mOpenTimer.get()) {
+    mOpenTimer = nullptr;
+
+    nsMenuParent* menuParent = GetMenuParent();
+    if (!IsOpen() && menuParent) {
+      // make sure we didn't open a context menu in the meantime
+      // (i.e. the user right-clicked while hovering over a submenu).
+      nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+      if (pm) {
+        if ((!pm->HasContextMenu(nullptr) || menuParent->IsContextMenu()) &&
+            mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::menuactive,
+                                  nsGkAtoms::_true, eCaseMatters)) {
+          OpenMenu(false);
+        }
+      }
+    }
+  } else if (aTimer == mBlinkTimer) {
+    switch (mBlinkState++) {
+      case 0:
+        NS_ASSERTION(false, "Blink timer fired while not blinking");
+        StopBlinking();
+        break;
+      case 1:
+        {
+          // Turn the highlight back on and wait for a while before closing the menu.
+          nsWeakFrame weakFrame(this);
+          mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::menuactive,
+                            NS_LITERAL_STRING("true"), true);
+          if (weakFrame.IsAlive()) {
+            aTimer->InitWithCallback(mTimerMediator, kBlinkDelay, nsITimer::TYPE_ONE_SHOT);
+          }
+        }
+        break;
+      default: {
+        nsMenuParent* menuParent = GetMenuParent();
+        if (menuParent) {
+          menuParent->LockMenuUntilClosed(false);
+        }
+        PassMenuCommandEventToPopupManager();
+        StopBlinking();
+        break;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+bool 
+nsMenuFrame::IsDisabled()
+{
+  return mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                               nsGkAtoms::_true, eCaseMatters);
+}
+
+void
+nsMenuFrame::UpdateMenuType()
+{
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::checkbox, &nsGkAtoms::radio, nullptr};
+  switch (mContent->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::type,
+                                    strings, eCaseMatters)) {
+    case 0: mType = eMenuType_Checkbox; break;
+    case 1:
+      mType = eMenuType_Radio;
+      mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::name, mGroupName);
+      break;
+
+    default:
+      if (mType != eMenuType_Normal) {
+        nsWeakFrame weakFrame(this);
+        mContent->UnsetAttr(kNameSpaceID_None, nsGkAtoms::checked,
+                            true);
+        ENSURE_TRUE(weakFrame.IsAlive());
+      }
+      mType = eMenuType_Normal;
+      break;
+  }
+  UpdateMenuSpecialState();
+}
+
+/* update checked-ness for type="checkbox" and type="radio" */
+void
+nsMenuFrame::UpdateMenuSpecialState()
+{
+  bool newChecked =
+    mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::checked,
+                          nsGkAtoms::_true, eCaseMatters); 
+  if (newChecked == mChecked) {
+    /* checked state didn't change */
+
+    if (mType != eMenuType_Radio)
+      return; // only Radio possibly cares about other kinds of change
+
+    if (!mChecked || mGroupName.IsEmpty())
+      return;                   // no interesting change
+  } else { 
+    mChecked = newChecked;
+    if (mType != eMenuType_Radio || !mChecked)
+      /*
+       * Unchecking something requires no further changes, and only
+       * menuRadio has to do additional work when checked.
+       */
+      return;
+  }
+
+  /*
+   * If we get this far, we're type=radio, and:
+   * - our name= changed, or
+   * - we went from checked="false" to checked="true"
+   */
+
+  /*
+   * Behavioural note:
+   * If we're checked and renamed _into_ an existing radio group, we are
+   * made the new checked item, and we unselect the previous one.
+   *
+   * The only other reasonable behaviour would be to check for another selected
+   * item in that group.  If found, unselect ourselves, otherwise we're the
+   * selected item.  That, however, would be a lot more work, and I don't think
+   * it's better at all.
+   */
+
+  /* walk siblings, looking for the other checked item with the same name */
+  // get the first sibling in this menu popup. This frame may be it, and if we're
+  // being called at creation time, this frame isn't yet in the parent's child list.
+  // All I'm saying is that this may fail, but it's most likely alright.
+  nsIFrame* firstMenuItem = nsXULPopupManager::GetNextMenuItem(GetParent(), nullptr, true);
+  nsIFrame* sib = firstMenuItem;
+  while (sib) {
+    nsMenuFrame* menu = do_QueryFrame(sib);
+    if (sib != this) {
+      if (menu && menu->GetMenuType() == eMenuType_Radio &&
+          menu->IsChecked() && menu->GetRadioGroupName() == mGroupName) {
+        /* uncheck the old item */
+        sib->GetContent()->UnsetAttr(kNameSpaceID_None, nsGkAtoms::checked,
+                                     true);
+        /* XXX in DEBUG, check to make sure that there aren't two checked items */
+        return;
+      }
+    }
+    sib = nsXULPopupManager::GetNextMenuItem(GetParent(), menu, true);
+    if (sib == firstMenuItem) {
+      break;
+    }
+  } 
+}
+
+void 
+nsMenuFrame::BuildAcceleratorText(bool aNotify)
+{
+  nsAutoString accelText;
+
+  if ((GetStateBits() & NS_STATE_ACCELTEXT_IS_DERIVED) == 0) {
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::acceltext, accelText);
+    if (!accelText.IsEmpty())
+      return;
+  }
+  // accelText is definitely empty here.
+
+  // Now we're going to compute the accelerator text, so remember that we did.
+  AddStateBits(NS_STATE_ACCELTEXT_IS_DERIVED);
+
+  // If anything below fails, just leave the accelerator text blank.
+  nsWeakFrame weakFrame(this);
+  mContent->UnsetAttr(kNameSpaceID_None, nsGkAtoms::acceltext, aNotify);
+  ENSURE_TRUE(weakFrame.IsAlive());
+
+  // See if we have a key node and use that instead.
+  nsAutoString keyValue;
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::key, keyValue);
+  if (keyValue.IsEmpty())
+    return;
+
+  // Turn the document into a DOM document so we can use getElementById
+  nsIDocument *document = mContent->GetUncomposedDoc();
+  if (!document)
+    return;
+
+  //XXXsmaug If mContent is in shadow dom, should we use
+  //         ShadowRoot::GetElementById()?
+  nsIContent *keyElement = document->GetElementById(keyValue);
+  if (!keyElement) {
+#ifdef DEBUG
+    nsAutoString label;
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::label, label);
+    nsAutoString msg = NS_LITERAL_STRING("Key '") +
+                       keyValue +
+                       NS_LITERAL_STRING("' of menu item '") +
+                       label +
+                       NS_LITERAL_STRING("' could not be found");
+    NS_WARNING(NS_ConvertUTF16toUTF8(msg).get());
+#endif
+    return;
+  }
+
+  // get the string to display as accelerator text
+  // check the key element's attributes in this order:
+  // |keytext|, |key|, |keycode|
+  nsAutoString accelString;
+  keyElement->GetAttr(kNameSpaceID_None, nsGkAtoms::keytext, accelString);
+
+  if (accelString.IsEmpty()) {
+    keyElement->GetAttr(kNameSpaceID_None, nsGkAtoms::key, accelString);
+
+    if (!accelString.IsEmpty()) {
+      ToUpperCase(accelString);
+    } else {
+      nsAutoString keyCode;
+      keyElement->GetAttr(kNameSpaceID_None, nsGkAtoms::keycode, keyCode);
+      ToUpperCase(keyCode);
+
+      nsresult rv;
+      nsCOMPtr<nsIStringBundleService> bundleService =
+        mozilla::services::GetStringBundleService();
+      if (bundleService) {
+        nsCOMPtr<nsIStringBundle> bundle;
+        rv = bundleService->CreateBundle("chrome://global/locale/keys.properties",
+                                         getter_AddRefs(bundle));
+
+        if (NS_SUCCEEDED(rv) && bundle) {
+          nsXPIDLString keyName;
+          rv = bundle->GetStringFromName(keyCode.get(), getter_Copies(keyName));
+          if (keyName)
+            accelString = keyName;
+        }
+      }
+
+      // nothing usable found, bail
+      if (accelString.IsEmpty())
+        return;
+    }
+  }
+
+  nsAutoString modifiers;
+  keyElement->GetAttr(kNameSpaceID_None, nsGkAtoms::modifiers, modifiers);
+  
+  char* str = ToNewCString(modifiers);
+  char* newStr;
+  char* token = nsCRT::strtok(str, ", \t", &newStr);
+
+  nsAutoString shiftText;
+  nsAutoString altText;
+  nsAutoString metaText;
+  nsAutoString controlText;
+  nsAutoString osText;
+  nsAutoString modifierSeparator;
+
+  nsContentUtils::GetShiftText(shiftText);
+  nsContentUtils::GetAltText(altText);
+  nsContentUtils::GetMetaText(metaText);
+  nsContentUtils::GetControlText(controlText);
+  nsContentUtils::GetOSText(osText);
+  nsContentUtils::GetModifierSeparatorText(modifierSeparator);
+
+  while (token) {
+      
+    if (PL_strcmp(token, "shift") == 0)
+      accelText += shiftText;
+    else if (PL_strcmp(token, "alt") == 0) 
+      accelText += altText; 
+    else if (PL_strcmp(token, "meta") == 0) 
+      accelText += metaText; 
+    else if (PL_strcmp(token, "os") == 0)
+      accelText += osText; 
+    else if (PL_strcmp(token, "control") == 0) 
+      accelText += controlText; 
+    else if (PL_strcmp(token, "accel") == 0) {
+      switch (WidgetInputEvent::AccelModifier()) {
+        case MODIFIER_META:
+          accelText += metaText;
+          break;
+        case MODIFIER_OS:
+          accelText += osText;
+          break;
+        case MODIFIER_ALT:
+          accelText += altText;
+          break;
+        case MODIFIER_CONTROL:
+          accelText += controlText;
+          break;
+        default:
+          MOZ_CRASH(
+            "Handle the new result of WidgetInputEvent::AccelModifier()");
+          break;
+      }
+    }
+    
+    accelText += modifierSeparator;
+
+    token = nsCRT::strtok(newStr, ", \t", &newStr);
+  }
+
+  free(str);
+
+  accelText += accelString;
+
+  mIgnoreAccelTextChange = true;
+  mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::acceltext, accelText, aNotify);
+  ENSURE_TRUE(weakFrame.IsAlive());
+
+  mIgnoreAccelTextChange = false;
+}
+
+void
+nsMenuFrame::Execute(WidgetGUIEvent* aEvent)
+{
+  // flip "checked" state if we're a checkbox menu, or an un-checked radio menu
+  bool needToFlipChecked = false;
+  if (mType == eMenuType_Checkbox || (mType == eMenuType_Radio && !mChecked)) {
+    needToFlipChecked = !mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::autocheck,
+                                               nsGkAtoms::_false, eCaseMatters);
+  }
+
+  nsCOMPtr<nsISound> sound(do_CreateInstance("@mozilla.org/sound;1"));
+  if (sound)
+    sound->PlayEventSound(nsISound::EVENT_MENU_EXECUTE);
+
+  StartBlinking(aEvent, needToFlipChecked);
+}
+
+bool
+nsMenuFrame::ShouldBlink()
+{
+  int32_t shouldBlink =
+    LookAndFeel::GetInt(LookAndFeel::eIntID_ChosenMenuItemsShouldBlink, 0);
+  if (!shouldBlink)
+    return false;
+
+  // Don't blink in editable menulists.
+  if (GetParentMenuListType() == eEditableMenuList)
+    return false;
+
+  return true;
+}
+
+void
+nsMenuFrame::StartBlinking(WidgetGUIEvent* aEvent, bool aFlipChecked)
+{
+  StopBlinking();
+  CreateMenuCommandEvent(aEvent, aFlipChecked);
+
+  if (!ShouldBlink()) {
+    PassMenuCommandEventToPopupManager();
+    return;
+  }
+
+  // Blink off.
+  nsWeakFrame weakFrame(this);
+  mContent->UnsetAttr(kNameSpaceID_None, nsGkAtoms::menuactive, true);
+  if (!weakFrame.IsAlive())
+    return;
+
+  nsMenuParent* menuParent = GetMenuParent();
+  if (menuParent) {
+    // Make this menu ignore events from now on.
+    menuParent->LockMenuUntilClosed(true);
+  }
+
+  // Set up a timer to blink back on.
+  mBlinkTimer = do_CreateInstance("@mozilla.org/timer;1");
+  mBlinkTimer->InitWithCallback(mTimerMediator, kBlinkDelay, nsITimer::TYPE_ONE_SHOT);
+  mBlinkState = 1;
+}
+
+void
+nsMenuFrame::StopBlinking()
+{
+  mBlinkState = 0;
+  if (mBlinkTimer) {
+    mBlinkTimer->Cancel();
+    mBlinkTimer = nullptr;
+  }
+  mDelayedMenuCommandEvent = nullptr;
+}
+
+void
+nsMenuFrame::CreateMenuCommandEvent(WidgetGUIEvent* aEvent, bool aFlipChecked)
+{
+  // Create a trusted event if the triggering event was trusted, or if
+  // we're called from chrome code (since at least one of our caller
+  // passes in a null event).
+  bool isTrusted = aEvent ? aEvent->IsTrusted() :
+                              nsContentUtils::IsCallerChrome();
+
+  bool shift = false, control = false, alt = false, meta = false;
+  WidgetInputEvent* inputEvent = aEvent ? aEvent->AsInputEvent() : nullptr;
+  if (inputEvent) {
+    shift = inputEvent->IsShift();
+    control = inputEvent->IsControl();
+    alt = inputEvent->IsAlt();
+    meta = inputEvent->IsMeta();
+  }
+
+  // Because the command event is firing asynchronously, a flag is needed to
+  // indicate whether user input is being handled. This ensures that a popup
+  // window won't get blocked.
+  bool userinput = EventStateManager::IsHandlingUserInput();
+
+  mDelayedMenuCommandEvent =
+    new nsXULMenuCommandEvent(mContent, isTrusted, shift, control, alt, meta,
+                              userinput, aFlipChecked);
+}
+
+void
+nsMenuFrame::PassMenuCommandEventToPopupManager()
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  nsMenuParent* menuParent = GetMenuParent();
+  if (pm && menuParent && mDelayedMenuCommandEvent) {
+    pm->ExecuteMenu(mContent, mDelayedMenuCommandEvent);
+  }
+  mDelayedMenuCommandEvent = nullptr;
+}
+
+void
+nsMenuFrame::RemoveFrame(ChildListID     aListID,
+                         nsIFrame*       aOldFrame)
+{
+  nsFrameList* popupList = GetPopupList();
+  if (popupList && popupList->FirstChild() == aOldFrame) {
+    popupList->RemoveFirstChild();
+    aOldFrame->Destroy();
+    DestroyPopupList();
+    PresContext()->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                       NS_FRAME_HAS_DIRTY_CHILDREN);
+    return;
+  }
+  nsBoxFrame::RemoveFrame(aListID, aOldFrame);
+}
+
+void
+nsMenuFrame::InsertFrames(ChildListID     aListID,
+                          nsIFrame*       aPrevFrame,
+                          nsFrameList&    aFrameList)
+{
+  if (!HasPopup() && (aListID == kPrincipalList || aListID == kPopupList)) {
+    SetPopupFrame(aFrameList);
+    if (HasPopup()) {
+#ifdef DEBUG_LAYOUT
+      nsBoxLayoutState state(PresContext());
+      SetXULDebug(state, aFrameList, mState & NS_STATE_CURRENTLY_IN_DEBUG);
+#endif
+
+      PresContext()->PresShell()->
+        FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                         NS_FRAME_HAS_DIRTY_CHILDREN);
+    }
+  }
+
+  if (aFrameList.IsEmpty())
+    return;
+
+  if (MOZ_UNLIKELY(aPrevFrame && aPrevFrame == GetPopup())) {
+    aPrevFrame = nullptr;
+  }
+
+  nsBoxFrame::InsertFrames(aListID, aPrevFrame, aFrameList);
+}
+
+void
+nsMenuFrame::AppendFrames(ChildListID     aListID,
+                          nsFrameList&    aFrameList)
+{
+  if (!HasPopup() && (aListID == kPrincipalList || aListID == kPopupList)) {
+    SetPopupFrame(aFrameList);
+    if (HasPopup()) {
+
+#ifdef DEBUG_LAYOUT
+      nsBoxLayoutState state(PresContext());
+      SetXULDebug(state, aFrameList, mState & NS_STATE_CURRENTLY_IN_DEBUG);
+#endif
+      PresContext()->PresShell()->
+        FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                         NS_FRAME_HAS_DIRTY_CHILDREN);
+    }
+  }
+
+  if (aFrameList.IsEmpty())
+    return;
+
+  nsBoxFrame::AppendFrames(aListID, aFrameList); 
+}
+
+bool
+nsMenuFrame::SizeToPopup(nsBoxLayoutState& aState, nsSize& aSize)
+{
+  if (!IsXULCollapsed()) {
+    bool widthSet, heightSet;
+    nsSize tmpSize(-1, 0);
+    nsIFrame::AddXULPrefSize(this, tmpSize, widthSet, heightSet);
+    if (!widthSet && GetXULFlex() == 0) {
+      nsMenuPopupFrame* popupFrame = GetPopup();
+      if (!popupFrame)
+        return false;
+      tmpSize = popupFrame->GetXULPrefSize(aState);
+
+      // Produce a size such that:
+      //  (1) the menu and its popup can be the same width
+      //  (2) there's enough room in the menu for the content and its
+      //      border-padding
+      //  (3) there's enough room in the popup for the content and its
+      //      scrollbar
+      nsMargin borderPadding;
+      GetXULBorderAndPadding(borderPadding);
+
+      // if there is a scroll frame, add the desired width of the scrollbar as well
+      nsIScrollableFrame* scrollFrame = do_QueryFrame(popupFrame->PrincipalChildList().FirstChild());
+      nscoord scrollbarWidth = 0;
+      if (scrollFrame) {
+        scrollbarWidth =
+          scrollFrame->GetDesiredScrollbarSizes(&aState).LeftRight();
+      }
+
+      aSize.width =
+        tmpSize.width + std::max(borderPadding.LeftRight(), scrollbarWidth);
+
+      return true;
+    }
+  }
+
+  return false;
+}
+
+nsSize
+nsMenuFrame::GetXULPrefSize(nsBoxLayoutState& aState)
+{
+  nsSize size = nsBoxFrame::GetXULPrefSize(aState);
+  DISPLAY_PREF_SIZE(this, size);
+
+  // If we are using sizetopopup="always" then
+  // nsBoxFrame will already have enforced the minimum size
+  if (!IsSizedToPopup(mContent, true) &&
+      IsSizedToPopup(mContent, false) &&
+      SizeToPopup(aState, size)) {
+    // We now need to ensure that size is within the min - max range.
+    nsSize minSize = nsBoxFrame::GetXULMinSize(aState);
+    nsSize maxSize = GetXULMaxSize(aState);
+    size = BoundsCheck(minSize, size, maxSize);
+  }
+
+  return size;
+}
+
+NS_IMETHODIMP
+nsMenuFrame::GetActiveChild(nsIDOMElement** aResult)
+{
+  nsMenuPopupFrame* popupFrame = GetPopup();
+  if (!popupFrame)
+    return NS_ERROR_FAILURE;
+
+  nsMenuFrame* menuFrame = popupFrame->GetCurrentMenuItem();
+  if (!menuFrame) {
+    *aResult = nullptr;
+  }
+  else {
+    nsCOMPtr<nsIDOMElement> elt(do_QueryInterface(menuFrame->GetContent()));
+    *aResult = elt;
+    NS_IF_ADDREF(*aResult);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMenuFrame::SetActiveChild(nsIDOMElement* aChild)
+{
+  nsMenuPopupFrame* popupFrame = GetPopup();
+  if (!popupFrame)
+    return NS_ERROR_FAILURE;
+
+  if (!aChild) {
+    // Remove the current selection
+    popupFrame->ChangeMenuItem(nullptr, false, false);
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIContent> child(do_QueryInterface(aChild));
+
+  nsMenuFrame* menu = do_QueryFrame(child->GetPrimaryFrame());
+  if (menu)
+    popupFrame->ChangeMenuItem(menu, false, false);
+  return NS_OK;
+}
+
+nsIScrollableFrame* nsMenuFrame::GetScrollTargetFrame()
+{
+  nsMenuPopupFrame* popupFrame = GetPopup();
+  if (!popupFrame)
+    return nullptr;
+  nsIFrame* childFrame = popupFrame->PrincipalChildList().FirstChild();
+  if (childFrame)
+    return popupFrame->GetScrollFrame(childFrame);
+  return nullptr;
+}
+
+// nsMenuTimerMediator implementation.
+NS_IMPL_ISUPPORTS(nsMenuTimerMediator, nsITimerCallback)
+
+/**
+ * Constructs a wrapper around an nsMenuFrame.
+ * @param aFrame nsMenuFrame to create a wrapper around.
+ */
+nsMenuTimerMediator::nsMenuTimerMediator(nsMenuFrame *aFrame) :
+  mFrame(aFrame)
+{
+  NS_ASSERTION(mFrame, "Must have frame");
+}
+
+nsMenuTimerMediator::~nsMenuTimerMediator()
+{
+}
+
+/**
+ * Delegates the notification to the contained frame if it has not been destroyed.
+ * @param aTimer Timer which initiated the callback.
+ * @return NS_ERROR_FAILURE if the frame has been destroyed.
+ */
+NS_IMETHODIMP nsMenuTimerMediator::Notify(nsITimer* aTimer)
+{
+  if (!mFrame)
+    return NS_ERROR_FAILURE;
+
+  return mFrame->Notify(aTimer);
+}
+
+/**
+ * Clear the pointer to the contained nsMenuFrame. This should be called
+ * when the contained nsMenuFrame is destroyed.
+ */
+void nsMenuTimerMediator::ClearFrame()
+{
+  mFrame = nullptr;
+}
diff --git a/layout/xul/nsMenuFrame.h b/layout/xul/nsMenuFrame.h
new file mode 100644
index 0000000000..1941ec69e6
--- /dev/null
+++ b/layout/xul/nsMenuFrame.h
@@ -0,0 +1,288 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// nsMenuFrame
+//
+
+#ifndef nsMenuFrame_h__
+#define nsMenuFrame_h__
+
+#include "nsIAtom.h"
+#include "nsCOMPtr.h"
+
+#include "nsBoxFrame.h"
+#include "nsFrameList.h"
+#include "nsGkAtoms.h"
+#include "nsMenuParent.h"
+#include "nsXULPopupManager.h"
+#include "nsITimer.h"
+#include "mozilla/Attributes.h"
+
+nsIFrame* NS_NewMenuFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+nsIFrame* NS_NewMenuItemFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+class nsIContent;
+
+#define NS_STATE_ACCELTEXT_IS_DERIVED  NS_STATE_BOX_CHILD_RESERVED
+
+// the type of menuitem
+enum nsMenuType {
+  // a normal menuitem where a command is carried out when activated
+  eMenuType_Normal = 0,
+  // a menuitem with a checkmark that toggles when activated
+  eMenuType_Checkbox = 1,
+  // a radio menuitem where only one of it and its siblings with the same
+  // name attribute can be checked at a time
+  eMenuType_Radio = 2
+};
+
+enum nsMenuListType {
+  eNotMenuList,      // not a menulist
+  eReadonlyMenuList, // <menulist/>
+  eEditableMenuList  // <menulist editable="true"/>
+};
+
+class nsMenuFrame;
+
+/**
+ * nsMenuTimerMediator is a wrapper around an nsMenuFrame which can be safely
+ * passed to timers. The class is reference counted unlike the underlying
+ * nsMenuFrame, so that it will exist as long as the timer holds a reference
+ * to it. The callback is delegated to the contained nsMenuFrame as long as
+ * the contained nsMenuFrame has not been destroyed.
+ */
+class nsMenuTimerMediator final : public nsITimerCallback
+{
+public:
+  explicit nsMenuTimerMediator(nsMenuFrame* aFrame);
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSITIMERCALLBACK
+
+  void ClearFrame();
+
+private:
+  ~nsMenuTimerMediator();
+
+  // Pointer to the wrapped frame.
+  nsMenuFrame* mFrame;
+};
+
+class nsMenuFrame final : public nsBoxFrame
+{
+public:
+  explicit nsMenuFrame(nsStyleContext* aContext);
+
+  NS_DECL_QUERYFRAME_TARGET(nsMenuFrame)
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState) override;
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+#ifdef DEBUG_LAYOUT
+  virtual nsresult SetXULDebug(nsBoxLayoutState& aState, bool aDebug) override;
+#endif
+
+  // The following methods are all overridden so that the menupopup
+  // can be stored in a separate list, so that it doesn't impact reflow of the
+  // actual menu item at all.
+  virtual const nsFrameList& GetChildList(ChildListID aList) const override;
+  virtual void GetChildLists(nsTArray<ChildList>* aLists) const override;
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  // Overridden to prevent events from going to children of the menu.
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) override;
+                                         
+  // this method can destroy the frame
+  virtual nsresult HandleEvent(nsPresContext* aPresContext,
+                               mozilla::WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  virtual void SetInitialChildList(ChildListID  aListID,
+                                   nsFrameList& aChildList) override;
+  virtual void AppendFrames(ChildListID     aListID,
+                            nsFrameList&    aFrameList) override;
+  virtual void InsertFrames(ChildListID     aListID,
+                            nsIFrame*       aPrevFrame,
+                            nsFrameList&    aFrameList) override;
+  virtual void RemoveFrame(ChildListID     aListID,
+                           nsIFrame*       aOldFrame) override;
+
+  virtual nsIAtom* GetType() const override { return nsGkAtoms::menuFrame; }
+
+  NS_IMETHOD SelectMenu(bool aActivateFlag);
+
+  virtual nsIScrollableFrame* GetScrollTargetFrame() override;
+
+  // Retrieve the element that the menu should be anchored to. By default this is
+  // the menu itself. However, the anchor attribute may refer to the value of an
+  // anonid within the menu's binding, or, if not found, the id of an element in
+  // the document.
+  nsIContent* GetAnchor();
+
+  /**
+   * NOTE: OpenMenu will open the menu asynchronously.
+   */
+  void OpenMenu(bool aSelectFirstItem);
+  // CloseMenu closes the menu asynchronously
+  void CloseMenu(bool aDeselectMenu);
+
+  bool IsChecked() { return mChecked; }
+
+  NS_IMETHOD GetActiveChild(nsIDOMElement** aResult);
+  NS_IMETHOD SetActiveChild(nsIDOMElement* aChild);
+
+  // called when the Enter key is pressed while the menuitem is the current
+  // one in its parent popup. This will carry out the command attached to
+  // the menuitem. If the menu should be opened, this frame will be returned,
+  // otherwise null will be returned.
+  nsMenuFrame* Enter(mozilla::WidgetGUIEvent* aEvent);
+
+  // Return the nearest menu bar or menupopup ancestor frame.
+  nsMenuParent* GetMenuParent() const;
+
+  const nsAString& GetRadioGroupName() { return mGroupName; }
+  nsMenuType GetMenuType() { return mType; }
+  nsMenuPopupFrame* GetPopup();
+
+  /**
+   * @return true if this frame has a popup child frame.
+   */
+  bool HasPopup() const
+  {
+    return (GetStateBits() & NS_STATE_MENU_HAS_POPUP_LIST) != 0;
+  }
+
+
+  // nsMenuFrame methods 
+
+  bool IsOnMenuBar() const
+  {
+    nsMenuParent* menuParent = GetMenuParent();
+    return menuParent && menuParent->IsMenuBar();
+  }
+  bool IsOnActiveMenuBar() const
+  {
+    nsMenuParent* menuParent = GetMenuParent();
+    return menuParent && menuParent->IsMenuBar() && menuParent->IsActive();
+  }
+  virtual bool IsOpen();
+  virtual bool IsMenu();
+  nsMenuListType GetParentMenuListType();
+  bool IsDisabled();
+  void ToggleMenuState();
+
+  // indiciate that the menu's popup has just been opened, so that the menu
+  // can update its open state. This method modifies the open attribute on
+  // the menu, so the frames could be gone after this call.
+  void PopupOpened();
+  // indiciate that the menu's popup has just been closed, so that the menu
+  // can update its open state. The menu should be unhighlighted if
+  // aDeselectedMenu is true. This method modifies the open attribute on
+  // the menu, so the frames could be gone after this call.
+  void PopupClosed(bool aDeselectMenu);
+
+  // returns true if this is a menu on another menu popup. A menu is a submenu
+  // if it has a parent popup or menupopup.
+  bool IsOnMenu() const
+  {
+    nsMenuParent* menuParent = GetMenuParent();
+    return menuParent && menuParent->IsMenu();
+  }
+  void SetIsMenu(bool aIsMenu) { mIsMenu = aIsMenu; }
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override
+  {
+      return MakeFrameName(NS_LITERAL_STRING("Menu"), aResult);
+  }
+#endif
+
+  static bool IsSizedToPopup(nsIContent* aContent, bool aRequireAlways);
+
+protected:
+  friend class nsMenuTimerMediator;
+  friend class nsASyncMenuInitialization;
+  friend class nsMenuAttributeChangedEvent;
+
+  /**
+   * Initialize the popup list to the first popup frame within
+   * aChildList. Removes the popup, if any, from aChildList.
+   */
+  void SetPopupFrame(nsFrameList& aChildList);
+
+  /**
+   * Get the popup frame list from the frame property.
+   * @return the property value if it exists, nullptr otherwise.
+   */
+  nsFrameList* GetPopupList() const;
+
+  /**
+   * Destroy the popup list property.  The list must exist and be empty.
+   */
+  void DestroyPopupList();
+
+  // Update the menu's type (normal, checkbox, radio).
+  // This method can destroy the frame.
+  void UpdateMenuType();
+  // Update the checked state of the menu, and for radios, clear any other
+  // checked items. This method can destroy the frame.
+  void UpdateMenuSpecialState();
+
+  // Examines the key node and builds the accelerator.
+  void BuildAcceleratorText(bool aNotify);
+
+  // Called to execute our command handler. This method can destroy the frame.
+  void Execute(mozilla::WidgetGUIEvent *aEvent);
+
+  // This method can destroy the frame
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+  virtual ~nsMenuFrame() { }
+
+  bool SizeToPopup(nsBoxLayoutState& aState, nsSize& aSize);
+
+  bool ShouldBlink();
+  void StartBlinking(mozilla::WidgetGUIEvent* aEvent, bool aFlipChecked);
+  void StopBlinking();
+  void CreateMenuCommandEvent(mozilla::WidgetGUIEvent* aEvent,
+                              bool aFlipChecked);
+  void PassMenuCommandEventToPopupManager();
+
+protected:
+#ifdef DEBUG_LAYOUT
+  nsresult SetXULDebug(nsBoxLayoutState& aState, nsIFrame* aList, bool aDebug);
+#endif
+  nsresult Notify(nsITimer* aTimer);
+
+  bool mIsMenu; // Whether or not we can even have children or not.
+  bool mChecked;              // are we checked?
+  bool mIgnoreAccelTextChange; // temporarily set while determining the accelerator key
+  nsMenuType mType;
+
+  // Reference to the mediator which wraps this frame.
+  RefPtr<nsMenuTimerMediator> mTimerMediator;
+
+  nsCOMPtr<nsITimer> mOpenTimer;
+  nsCOMPtr<nsITimer> mBlinkTimer;
+
+  uint8_t mBlinkState; // 0: not blinking, 1: off, 2: on
+  RefPtr<nsXULMenuCommandEvent> mDelayedMenuCommandEvent;
+
+  nsString mGroupName;
+
+}; // class nsMenuFrame
+
+#endif
diff --git a/layout/xul/nsMenuParent.h b/layout/xul/nsMenuParent.h
new file mode 100644
index 0000000000..19c2dcd7cc
--- /dev/null
+++ b/layout/xul/nsMenuParent.h
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMenuParent_h___
+#define nsMenuParent_h___
+
+class nsMenuFrame;
+
+/*
+ * nsMenuParent is an interface implemented by nsMenuBarFrame and nsMenuPopupFrame
+ * as both serve as parent frames to nsMenuFrame.
+ *
+ * Don't implement this interface on other classes unless you also fix up references,
+ * as this interface is directly cast to and from nsMenuBarFrame and nsMenuPopupFrame.
+ */
+
+class nsMenuParent {
+
+public:
+  // returns the menu frame of the currently active item within the menu
+  virtual nsMenuFrame *GetCurrentMenuItem() = 0;
+  // sets the currently active menu frame.
+  NS_IMETHOD SetCurrentMenuItem(nsMenuFrame* aMenuItem) = 0;
+  // indicate that the current menu frame is being destroyed, so clear the
+  // current menu item
+  virtual void CurrentMenuIsBeingDestroyed() = 0;
+  // deselects the current item and closes its popup if any, then selects the
+  // new item aMenuItem. For a menubar, if another menu is already open, the
+  // new menu aMenuItem is opened. In this case, if aSelectFirstItem is true,
+  // select the first item in it. For menupopups, the menu is not opened and
+  // the aSelectFirstItem argument is not used. The aFromKey argument indicates
+  // that the keyboard was used to navigate to the new menu item.
+  NS_IMETHOD ChangeMenuItem(nsMenuFrame* aMenuItem,
+                            bool aSelectFirstItem,
+                            bool aFromKey) = 0;
+
+  // returns true if the menupopup is open. For menubars, returns false.
+  virtual bool IsOpen() = 0;
+  // returns true if the menubar is currently active. For menupopups, returns false.
+  virtual bool IsActive() = 0;
+  // returns true if this is a menubar. If false, it is a popup
+  virtual bool IsMenuBar() = 0;
+  // returns true if this is a menu, which has a tag of menupopup or popup.
+  // Otherwise, this returns false
+  virtual bool IsMenu() = 0;
+  // returns true if this is a context menu
+  virtual bool IsContextMenu() = 0;
+
+  // indicate that the menubar should become active or inactive
+  NS_IMETHOD SetActive(bool aActiveFlag) = 0;
+
+  // notify that the menu has been closed and any active state should be
+  // cleared. This should return true if the menu should be deselected
+  // by the caller.
+  virtual bool MenuClosed() = 0;
+
+  // Lock this menu and its parents until they're closed or unlocked.
+  // A menu being "locked" means that all events inside it that would change the
+  // selected menu item should be ignored.
+  // This is used when closing the popup is delayed because of a blink or fade
+  // animation.
+  virtual void LockMenuUntilClosed(bool aLock) = 0;
+  virtual bool IsMenuLocked() = 0;
+};
+
+#endif
+
diff --git a/layout/xul/nsMenuPopupFrame.cpp b/layout/xul/nsMenuPopupFrame.cpp
new file mode 100644
index 0000000000..6e706e49c2
--- /dev/null
+++ b/layout/xul/nsMenuPopupFrame.cpp
@@ -0,0 +1,2442 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sw=2 et tw=78: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsMenuPopupFrame.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+#include "nsIAtom.h"
+#include "nsPresContext.h"
+#include "nsStyleContext.h"
+#include "nsCSSRendering.h"
+#include "nsNameSpaceManager.h"
+#include "nsViewManager.h"
+#include "nsWidgetsCID.h"
+#include "nsMenuFrame.h"
+#include "nsMenuBarFrame.h"
+#include "nsPopupSetFrame.h"
+#include "nsPIDOMWindow.h"
+#include "nsIDOMKeyEvent.h"
+#include "nsIDOMScreen.h"
+#include "nsIPresShell.h"
+#include "nsFrameManager.h"
+#include "nsIDocument.h"
+#include "nsRect.h"
+#include "nsIComponentManager.h"
+#include "nsBoxLayoutState.h"
+#include "nsIScrollableFrame.h"
+#include "nsIRootBox.h"
+#include "nsIDocShell.h"
+#include "nsReadableUtils.h"
+#include "nsUnicharUtils.h"
+#include "nsLayoutUtils.h"
+#include "nsContentUtils.h"
+#include "nsCSSFrameConstructor.h"
+#include "nsPIWindowRoot.h"
+#include "nsIReflowCallback.h"
+#include "nsBindingManager.h"
+#include "nsIDocShellTreeOwner.h"
+#include "nsIBaseWindow.h"
+#include "nsISound.h"
+#include "nsIScreenManager.h"
+#include "nsIServiceManager.h"
+#include "nsThemeConstants.h"
+#include "nsTransitionManager.h"
+#include "nsDisplayList.h"
+#include "nsIDOMXULSelectCntrlItemEl.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/EventStateManager.h"
+#include "mozilla/EventStates.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/PopupBoxObject.h"
+#include <algorithm>
+
+using namespace mozilla;
+using mozilla::dom::PopupBoxObject;
+
+int8_t nsMenuPopupFrame::sDefaultLevelIsTop = -1;
+
+DOMTimeStamp nsMenuPopupFrame::sLastKeyTime = 0;
+
+// XXX, kyle.yuan@sun.com, there are 4 definitions for the same purpose:
+//  nsMenuPopupFrame.h, nsListControlFrame.cpp, listbox.xml, tree.xml
+//  need to find a good place to put them together.
+//  if someone changes one, please also change the other.
+uint32_t nsMenuPopupFrame::sTimeoutOfIncrementalSearch = 1000;
+
+const char* kPrefIncrementalSearchTimeout =
+  "ui.menu.incremental_search.timeout";
+
+// NS_NewMenuPopupFrame
+//
+// Wrapper for creating a new menu popup container
+//
+nsIFrame*
+NS_NewMenuPopupFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsMenuPopupFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsMenuPopupFrame)
+
+NS_QUERYFRAME_HEAD(nsMenuPopupFrame)
+  NS_QUERYFRAME_ENTRY(nsMenuPopupFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsBoxFrame)
+
+//
+// nsMenuPopupFrame ctor
+//
+nsMenuPopupFrame::nsMenuPopupFrame(nsStyleContext* aContext)
+  :nsBoxFrame(aContext),
+  mCurrentMenu(nullptr),
+  mPrefSize(-1, -1),
+  mLastClientOffset(0, 0),
+  mPopupType(ePopupTypePanel),
+  mPopupState(ePopupClosed),
+  mPopupAlignment(POPUPALIGNMENT_NONE),
+  mPopupAnchor(POPUPALIGNMENT_NONE),
+  mPosition(POPUPPOSITION_UNKNOWN),
+  mConsumeRollupEvent(PopupBoxObject::ROLLUP_DEFAULT),
+  mFlip(FlipType_Default),
+  mIsOpenChanged(false),
+  mIsContextMenu(false),
+  mAdjustOffsetForContextMenu(false),
+  mGeneratedChildren(false),
+  mMenuCanOverlapOSBar(false),
+  mShouldAutoPosition(true),
+  mInContentShell(true),
+  mIsMenuLocked(false),
+  mMouseTransparent(false),
+  mHFlip(false),
+  mVFlip(false),
+  mAnchorType(MenuPopupAnchorType_Node)
+{
+  // the preference name is backwards here. True means that the 'top' level is
+  // the default, and false means that the 'parent' level is the default.
+  if (sDefaultLevelIsTop >= 0)
+    return;
+  sDefaultLevelIsTop =
+    Preferences::GetBool("ui.panel.default_level_parent", false);
+  Preferences::AddUintVarCache(&sTimeoutOfIncrementalSearch,
+                               kPrefIncrementalSearchTimeout, 1000);
+} // ctor
+
+void
+nsMenuPopupFrame::Init(nsIContent*       aContent,
+                       nsContainerFrame* aParent,
+                       nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  // lookup if we're allowed to overlap the OS bar (menubar/taskbar) from the
+  // look&feel object
+  mMenuCanOverlapOSBar =
+    LookAndFeel::GetInt(LookAndFeel::eIntID_MenusCanOverlapOSBar) != 0;
+
+  CreatePopupView();
+
+  // XXX Hack. The popup's view should float above all other views,
+  // so we use the nsView::SetFloating() to tell the view manager
+  // about that constraint.
+  nsView* ourView = GetView();
+  nsViewManager* viewManager = ourView->GetViewManager();
+  viewManager->SetViewFloating(ourView, true);
+
+  mPopupType = ePopupTypePanel;
+  nsIDocument* doc = aContent->OwnerDoc();
+  int32_t namespaceID;
+  nsCOMPtr<nsIAtom> tag = doc->BindingManager()->ResolveTag(aContent, &namespaceID);
+  if (namespaceID == kNameSpaceID_XUL) {
+    if (tag == nsGkAtoms::menupopup || tag == nsGkAtoms::popup)
+      mPopupType = ePopupTypeMenu;
+    else if (tag == nsGkAtoms::tooltip)
+      mPopupType = ePopupTypeTooltip;
+  }
+
+  nsCOMPtr<nsIDocShellTreeItem> dsti = PresContext()->GetDocShell();
+  if (dsti && dsti->ItemType() == nsIDocShellTreeItem::typeChrome) {
+    mInContentShell = false;
+  }
+
+  // To improve performance, create the widget for the popup only if it is not
+  // a leaf. Leaf popups such as menus will create their widgets later when
+  // the popup opens.
+  if (!IsLeaf() && !ourView->HasWidget()) {
+    CreateWidgetForView(ourView);
+  }
+
+  if (aContent->NodeInfo()->Equals(nsGkAtoms::tooltip, kNameSpaceID_XUL) &&
+      aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::_default,
+                            nsGkAtoms::_true, eIgnoreCase)) {
+    nsIRootBox* rootBox =
+      nsIRootBox::GetRootBox(PresContext()->GetPresShell());
+    if (rootBox) {
+      rootBox->SetDefaultTooltip(aContent);
+    }
+  }
+
+  AddStateBits(NS_FRAME_IN_POPUP);
+}
+
+bool
+nsMenuPopupFrame::IsNoAutoHide() const
+{
+  // Panels with noautohide="true" don't hide when the mouse is clicked
+  // outside of them, or when another application is made active. Non-autohide
+  // panels cannot be used in content windows.
+  return (!mInContentShell && mPopupType == ePopupTypePanel &&
+           mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::noautohide,
+                                 nsGkAtoms::_true, eIgnoreCase));
+}
+
+nsPopupLevel
+nsMenuPopupFrame::PopupLevel(bool aIsNoAutoHide) const
+{
+  // The popup level is determined as follows, in this order:
+  //   1. non-panels (menus and tooltips) are always topmost
+  //   2. any specified level attribute
+  //   3. if a titlebar attribute is set, use the 'floating' level
+  //   4. if this is a noautohide panel, use the 'parent' level
+  //   5. use the platform-specific default level
+
+  // If this is not a panel, this is always a top-most popup.
+  if (mPopupType != ePopupTypePanel)
+    return ePopupLevelTop;
+
+  // If the level attribute has been set, use that.
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::top, &nsGkAtoms::parent, &nsGkAtoms::floating, nullptr};
+  switch (mContent->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::level,
+                                    strings, eCaseMatters)) {
+    case 0:
+      return ePopupLevelTop;
+    case 1:
+      return ePopupLevelParent;
+    case 2:
+      return ePopupLevelFloating;
+  }
+
+  // Panels with titlebars most likely want to be floating popups.
+  if (mContent->HasAttr(kNameSpaceID_None, nsGkAtoms::titlebar))
+    return ePopupLevelFloating;
+
+  // If this panel is a noautohide panel, the default is the parent level.
+  if (aIsNoAutoHide)
+    return ePopupLevelParent;
+
+  // Otherwise, the result depends on the platform.
+  return sDefaultLevelIsTop ? ePopupLevelTop : ePopupLevelParent;
+}
+
+void
+nsMenuPopupFrame::EnsureWidget()
+{
+  nsView* ourView = GetView();
+  if (!ourView->HasWidget()) {
+    NS_ASSERTION(!mGeneratedChildren && !PrincipalChildList().FirstChild(),
+                 "Creating widget for MenuPopupFrame with children");
+    CreateWidgetForView(ourView);
+  }
+}
+
+nsresult
+nsMenuPopupFrame::CreateWidgetForView(nsView* aView)
+{
+  // Create a widget for ourselves.
+  nsWidgetInitData widgetData;
+  widgetData.mWindowType = eWindowType_popup;
+  widgetData.mBorderStyle = eBorderStyle_default;
+  widgetData.clipSiblings = true;
+  widgetData.mPopupHint = mPopupType;
+  widgetData.mNoAutoHide = IsNoAutoHide();
+
+  if (!mInContentShell) {
+    // A drag popup may be used for non-static translucent drag feedback
+    if (mPopupType == ePopupTypePanel &&
+        mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                              nsGkAtoms::drag, eIgnoreCase)) {
+      widgetData.mIsDragPopup = true;
+    }
+
+    // If mousethrough="always" is set directly on the popup, then the widget
+    // should ignore mouse events, passing them through to the content behind.
+    mMouseTransparent = GetStateBits() & NS_FRAME_MOUSE_THROUGH_ALWAYS;
+    widgetData.mMouseTransparent = mMouseTransparent;
+  }
+
+  nsAutoString title;
+  if (mContent && widgetData.mNoAutoHide) {
+    if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::titlebar,
+                              nsGkAtoms::normal, eCaseMatters)) {
+      widgetData.mBorderStyle = eBorderStyle_title;
+
+      mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::label, title);
+
+      if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::close,
+                                nsGkAtoms::_true, eCaseMatters)) {
+        widgetData.mBorderStyle =
+          static_cast<enum nsBorderStyle>(widgetData.mBorderStyle | eBorderStyle_close);
+      }
+    }
+  }
+
+  nsTransparencyMode mode = nsLayoutUtils::GetFrameTransparency(this, this);
+  nsIContent* parentContent = GetContent()->GetParent();
+  nsIAtom *tag = nullptr;
+  if (parentContent && parentContent->IsXULElement())
+    tag = parentContent->NodeInfo()->NameAtom();
+  widgetData.mSupportTranslucency = mode == eTransparencyTransparent;
+  widgetData.mDropShadow = !(mode == eTransparencyTransparent || tag == nsGkAtoms::menulist);
+  widgetData.mPopupLevel = PopupLevel(widgetData.mNoAutoHide);
+
+  // panels which have a parent level need a parent widget. This allows them to
+  // always appear in front of the parent window but behind other windows that
+  // should be in front of it.
+  nsCOMPtr<nsIWidget> parentWidget;
+  if (widgetData.mPopupLevel != ePopupLevelTop) {
+    nsCOMPtr<nsIDocShellTreeItem> dsti = PresContext()->GetDocShell();
+    if (!dsti)
+      return NS_ERROR_FAILURE;
+
+    nsCOMPtr<nsIDocShellTreeOwner> treeOwner;
+    dsti->GetTreeOwner(getter_AddRefs(treeOwner));
+    if (!treeOwner) return NS_ERROR_FAILURE;
+
+    nsCOMPtr<nsIBaseWindow> baseWindow(do_QueryInterface(treeOwner));
+    if (baseWindow)
+      baseWindow->GetMainWidget(getter_AddRefs(parentWidget));
+  }
+
+  nsresult rv = aView->CreateWidgetForPopup(&widgetData, parentWidget,
+                                            true, true);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsIWidget* widget = aView->GetWidget();
+  widget->SetTransparencyMode(mode);
+  widget->SetWindowShadowStyle(GetShadowStyle());
+
+  // most popups don't have a title so avoid setting the title if there isn't one
+  if (!title.IsEmpty()) {
+    widget->SetTitle(title);
+  }
+
+  return NS_OK;
+}
+
+uint8_t
+nsMenuPopupFrame::GetShadowStyle()
+{
+  uint8_t shadow = StyleUIReset()->mWindowShadow;
+  if (shadow != NS_STYLE_WINDOW_SHADOW_DEFAULT)
+    return shadow;
+
+  switch (StyleDisplay()->mAppearance) {
+    case NS_THEME_TOOLTIP:
+      return NS_STYLE_WINDOW_SHADOW_TOOLTIP;
+    case NS_THEME_MENUPOPUP:
+      return NS_STYLE_WINDOW_SHADOW_MENU;
+  }
+  return NS_STYLE_WINDOW_SHADOW_DEFAULT;
+}
+
+NS_IMETHODIMP nsXULPopupShownEvent::Run()
+{
+  nsMenuPopupFrame* popup = do_QueryFrame(mPopup->GetPrimaryFrame());
+  // Set the state to visible if the popup is still open.
+  if (popup && popup->IsOpen()) {
+    popup->SetPopupState(ePopupShown);
+  }
+
+  WidgetMouseEvent event(true, eXULPopupShown, nullptr,
+                         WidgetMouseEvent::eReal);
+  return EventDispatcher::Dispatch(mPopup, mPresContext, &event);                 
+}
+
+NS_IMETHODIMP nsXULPopupShownEvent::HandleEvent(nsIDOMEvent* aEvent)
+{
+  nsMenuPopupFrame* popup = do_QueryFrame(mPopup->GetPrimaryFrame());
+  nsCOMPtr<nsIDOMEventTarget> eventTarget;
+  aEvent->GetTarget(getter_AddRefs(eventTarget));
+  // Ignore events not targeted at the popup itself (ie targeted at
+  // descendants):
+  if (!SameCOMIdentity(mPopup, eventTarget)) {
+    return NS_OK;
+  }
+  if (popup) {
+    // ResetPopupShownDispatcher will delete the reference to this, so keep
+    // another one until Run is finished.
+    RefPtr<nsXULPopupShownEvent> event = this;
+    // Only call Run if it the dispatcher was assigned. This avoids calling the
+    // Run method if the transitionend event fires multiple times.
+    if (popup->ClearPopupShownDispatcher()) {
+      return Run();
+    }
+  }
+
+  CancelListener();
+  return NS_OK;
+}
+
+void nsXULPopupShownEvent::CancelListener()
+{
+  mPopup->RemoveSystemEventListener(NS_LITERAL_STRING("transitionend"), this, false);
+}
+
+NS_IMPL_ISUPPORTS_INHERITED(nsXULPopupShownEvent, Runnable, nsIDOMEventListener);
+
+void
+nsMenuPopupFrame::SetInitialChildList(ChildListID  aListID,
+                                      nsFrameList& aChildList)
+{
+  // unless the list is empty, indicate that children have been generated.
+  if (aListID == kPrincipalList && aChildList.NotEmpty()) {
+    mGeneratedChildren = true;
+  }
+  nsBoxFrame::SetInitialChildList(aListID, aChildList);
+}
+
+bool
+nsMenuPopupFrame::IsLeaf() const
+{
+  if (mGeneratedChildren)
+    return false;
+
+  if (mPopupType != ePopupTypeMenu) {
+    // any panel with a type attribute, such as the autocomplete popup,
+    // is always generated right away.
+    return !mContent->HasAttr(kNameSpaceID_None, nsGkAtoms::type);
+  }
+
+  // menu popups generate their child frames lazily only when opened, so
+  // behave like a leaf frame. However, generate child frames normally if
+  // the parent menu has a sizetopopup attribute. In this case the size of
+  // the parent menu is dependent on the size of the popup, so the frames
+  // need to exist in order to calculate this size.
+  nsIContent* parentContent = mContent->GetParent();
+  return (parentContent &&
+          !parentContent->HasAttr(kNameSpaceID_None, nsGkAtoms::sizetopopup));
+}
+
+void
+nsMenuPopupFrame::LayoutPopup(nsBoxLayoutState& aState, nsIFrame* aParentMenu,
+                              nsIFrame* aAnchor, bool aSizedToPopup)
+{
+  if (!mGeneratedChildren)
+    return;
+
+  SchedulePaint();
+
+  bool shouldPosition = true;
+  bool isOpen = IsOpen();
+  if (!isOpen) {
+    // if the popup is not open, only do layout while showing or if the menu
+    // is sized to the popup
+    shouldPosition = (mPopupState == ePopupShowing || mPopupState == ePopupPositioning);
+    if (!shouldPosition && !aSizedToPopup) {
+      RemoveStateBits(NS_FRAME_FIRST_REFLOW);
+      return;
+    }
+  }
+
+  // if the popup has just been opened, make sure the scrolled window is at 0,0
+  // Don't scroll menulists as they will scroll to their selected item on their own.
+  if (mIsOpenChanged && !IsMenuList()) {
+    nsIScrollableFrame *scrollframe = do_QueryFrame(nsBox::GetChildXULBox(this));
+    if (scrollframe) {
+      nsWeakFrame weakFrame(this);
+      scrollframe->ScrollTo(nsPoint(0,0), nsIScrollableFrame::INSTANT);
+      if (!weakFrame.IsAlive()) {
+        return;
+      }
+    }
+  }
+
+  // get the preferred, minimum and maximum size. If the menu is sized to the
+  // popup, then the popup's width is the menu's width.
+  nsSize prefSize = GetXULPrefSize(aState);
+  nsSize minSize = GetXULMinSize(aState); 
+  nsSize maxSize = GetXULMaxSize(aState);
+
+  if (aSizedToPopup) {
+    prefSize.width = aParentMenu->GetRect().width;
+  }
+  prefSize = BoundsCheck(minSize, prefSize, maxSize);
+
+  // if the size changed then set the bounds to be the preferred size
+  bool sizeChanged = (mPrefSize != prefSize);
+  if (sizeChanged) {
+    SetXULBounds(aState, nsRect(0, 0, prefSize.width, prefSize.height), false);
+    mPrefSize = prefSize;
+  }
+
+  bool needCallback = false;
+  if (shouldPosition) {
+    SetPopupPosition(aAnchor, false, aSizedToPopup, mPopupState == ePopupPositioning);
+    needCallback = true;
+  }
+
+  nsRect bounds(GetRect());
+  XULLayout(aState);
+
+  // if the width or height changed, readjust the popup position. This is a
+  // special case for tooltips where the preferred height doesn't include the
+  // real height for its inline element, but does once it is laid out.
+  // This is bug 228673 which doesn't have a simple fix.
+  bool rePosition = shouldPosition && (mPosition == POPUPPOSITION_SELECTION);
+  if (!aParentMenu) {
+    nsSize newsize = GetSize();
+    if (newsize.width > bounds.width || newsize.height > bounds.height) {
+      // the size after layout was larger than the preferred size,
+      // so set the preferred size accordingly
+      mPrefSize = newsize;
+      if (isOpen) {
+        rePosition = true;
+        needCallback = true;
+      }
+    }
+  }
+
+  if (rePosition) {
+    SetPopupPosition(aAnchor, false, aSizedToPopup, false);
+  }
+
+  nsPresContext* pc = PresContext();
+  nsView* view = GetView();
+
+  if (sizeChanged) {
+    // If the size of the popup changed, apply any size constraints.
+    nsIWidget* widget = view->GetWidget();
+    if (widget) {
+      SetSizeConstraints(pc, widget, minSize, maxSize);
+    }
+  }
+
+  if (isOpen) {
+    nsViewManager* viewManager = view->GetViewManager();
+    nsRect rect = GetRect();
+    rect.x = rect.y = 0;
+    viewManager->ResizeView(view, rect);
+
+    if (mPopupState == ePopupOpening) {
+      mPopupState = ePopupVisible;
+    }
+
+    viewManager->SetViewVisibility(view, nsViewVisibility_kShow);
+    nsContainerFrame::SyncFrameViewProperties(pc, this, nullptr, view, 0);
+  }
+
+  // finally, if the popup just opened, send a popupshown event
+  if (mIsOpenChanged) {
+    mIsOpenChanged = false;
+
+    // Make sure the current selection in a menulist is visible.
+    if (IsMenuList() && mCurrentMenu) {
+      EnsureMenuItemIsVisible(mCurrentMenu);
+    }
+
+#ifndef MOZ_WIDGET_GTK
+    // If the animate attribute is set to open, check for a transition and wait
+    // for it to finish before firing the popupshown event.
+    if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::animate,
+                              nsGkAtoms::open, eCaseMatters) &&
+        nsLayoutUtils::HasCurrentTransitions(this)) {
+      mPopupShownDispatcher = new nsXULPopupShownEvent(mContent, pc);
+      mContent->AddSystemEventListener(NS_LITERAL_STRING("transitionend"),
+                                       mPopupShownDispatcher, false, false);
+      return;
+    }
+#endif
+
+    // If there are no transitions, fire the popupshown event right away.
+    nsCOMPtr<nsIRunnable> event = new nsXULPopupShownEvent(GetContent(), pc);
+    NS_DispatchToCurrentThread(event);
+  }
+
+  if (needCallback && !mReflowCallbackData.mPosted) {
+    pc->PresShell()->PostReflowCallback(this);
+    mReflowCallbackData.MarkPosted(aAnchor, aSizedToPopup);
+  }
+}
+
+bool
+nsMenuPopupFrame::ReflowFinished()
+{
+  SetPopupPosition(mReflowCallbackData.mAnchor, false, mReflowCallbackData.mSizedToPopup, false);
+
+  mReflowCallbackData.Clear();
+
+  return false;
+}
+
+void
+nsMenuPopupFrame::ReflowCallbackCanceled()
+{
+  mReflowCallbackData.Clear();
+}
+
+bool
+nsMenuPopupFrame::IsMenuList()
+{
+  nsIFrame* parentMenu = GetParent();
+  if (!parentMenu) {
+    return false;
+  }
+
+  nsCOMPtr<nsIDOMXULMenuListElement> menulist = do_QueryInterface(parentMenu->GetContent());
+  return menulist != nullptr;
+}
+
+nsIContent*
+nsMenuPopupFrame::GetTriggerContent(nsMenuPopupFrame* aMenuPopupFrame)
+{
+  while (aMenuPopupFrame) {
+    if (aMenuPopupFrame->mTriggerContent)
+      return aMenuPopupFrame->mTriggerContent;
+
+    // check up the menu hierarchy until a popup with a trigger node is found
+    nsMenuFrame* menuFrame = do_QueryFrame(aMenuPopupFrame->GetParent());
+    if (!menuFrame)
+      break;
+
+    nsMenuParent* parentPopup = menuFrame->GetMenuParent();
+    if (!parentPopup || !parentPopup->IsMenu())
+      break;
+
+    aMenuPopupFrame = static_cast<nsMenuPopupFrame *>(parentPopup);
+  }
+
+  return nullptr;
+}
+
+void
+nsMenuPopupFrame::InitPositionFromAnchorAlign(const nsAString& aAnchor,
+                                              const nsAString& aAlign)
+{
+  mTriggerContent = nullptr;
+
+  if (aAnchor.EqualsLiteral("topleft"))
+    mPopupAnchor = POPUPALIGNMENT_TOPLEFT;
+  else if (aAnchor.EqualsLiteral("topright"))
+    mPopupAnchor = POPUPALIGNMENT_TOPRIGHT;
+  else if (aAnchor.EqualsLiteral("bottomleft"))
+    mPopupAnchor = POPUPALIGNMENT_BOTTOMLEFT;
+  else if (aAnchor.EqualsLiteral("bottomright"))
+    mPopupAnchor = POPUPALIGNMENT_BOTTOMRIGHT;
+  else if (aAnchor.EqualsLiteral("leftcenter"))
+    mPopupAnchor = POPUPALIGNMENT_LEFTCENTER;
+  else if (aAnchor.EqualsLiteral("rightcenter"))
+    mPopupAnchor = POPUPALIGNMENT_RIGHTCENTER;
+  else if (aAnchor.EqualsLiteral("topcenter"))
+    mPopupAnchor = POPUPALIGNMENT_TOPCENTER;
+  else if (aAnchor.EqualsLiteral("bottomcenter"))
+    mPopupAnchor = POPUPALIGNMENT_BOTTOMCENTER;
+  else
+    mPopupAnchor = POPUPALIGNMENT_NONE;
+
+  if (aAlign.EqualsLiteral("topleft"))
+    mPopupAlignment = POPUPALIGNMENT_TOPLEFT;
+  else if (aAlign.EqualsLiteral("topright"))
+    mPopupAlignment = POPUPALIGNMENT_TOPRIGHT;
+  else if (aAlign.EqualsLiteral("bottomleft"))
+    mPopupAlignment = POPUPALIGNMENT_BOTTOMLEFT;
+  else if (aAlign.EqualsLiteral("bottomright"))
+    mPopupAlignment = POPUPALIGNMENT_BOTTOMRIGHT;
+  else
+    mPopupAlignment = POPUPALIGNMENT_NONE;
+
+  mPosition = POPUPPOSITION_UNKNOWN;
+}
+
+void
+nsMenuPopupFrame::InitializePopup(nsIContent* aAnchorContent,
+                                  nsIContent* aTriggerContent,
+                                  const nsAString& aPosition,
+                                  int32_t aXPos, int32_t aYPos,
+                                  MenuPopupAnchorType aAnchorType,
+                                  bool aAttributesOverride)
+{
+  EnsureWidget();
+
+  mPopupState = ePopupShowing;
+  mAnchorContent = aAnchorContent;
+  mTriggerContent = aTriggerContent;
+  mXPos = aXPos;
+  mYPos = aYPos;
+  mAdjustOffsetForContextMenu = false;
+  mVFlip = false;
+  mHFlip = false;
+  mAlignmentOffset = 0;
+
+  mAnchorType = aAnchorType;
+
+  // if aAttributesOverride is true, then the popupanchor, popupalign and
+  // position attributes on the <popup> override those values passed in.
+  // If false, those attributes are only used if the values passed in are empty
+  if (aAnchorContent || aAnchorType == MenuPopupAnchorType_Rect) {
+    nsAutoString anchor, align, position, flip;
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::popupanchor, anchor);
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::popupalign, align);
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::position, position);
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::flip, flip);
+
+    if (aAttributesOverride) {
+      // if the attributes are set, clear the offset position. Otherwise,
+      // the offset is used to adjust the position from the anchor point
+      if (anchor.IsEmpty() && align.IsEmpty() && position.IsEmpty())
+        position.Assign(aPosition);
+      else
+        mXPos = mYPos = 0;
+    }
+    else if (!aPosition.IsEmpty()) {
+      position.Assign(aPosition);
+    }
+
+    if (flip.EqualsLiteral("none")) {
+      mFlip = FlipType_None;
+    } else if (flip.EqualsLiteral("both")) {
+      mFlip = FlipType_Both;
+    } else if (flip.EqualsLiteral("slide")) {
+      mFlip = FlipType_Slide;
+    }
+
+    position.CompressWhitespace();
+    int32_t spaceIdx = position.FindChar(' ');
+    // if there is a space in the position, assume it is the anchor and
+    // alignment as two separate tokens.
+    if (spaceIdx >= 0) {
+      InitPositionFromAnchorAlign(Substring(position, 0, spaceIdx), Substring(position, spaceIdx + 1));
+    }
+    else if (position.EqualsLiteral("before_start")) {
+      mPopupAnchor = POPUPALIGNMENT_TOPLEFT;
+      mPopupAlignment = POPUPALIGNMENT_BOTTOMLEFT;
+      mPosition = POPUPPOSITION_BEFORESTART;
+    }
+    else if (position.EqualsLiteral("before_end")) {
+      mPopupAnchor = POPUPALIGNMENT_TOPRIGHT;
+      mPopupAlignment = POPUPALIGNMENT_BOTTOMRIGHT;
+      mPosition = POPUPPOSITION_BEFOREEND;
+    }
+    else if (position.EqualsLiteral("after_start")) {
+      mPopupAnchor = POPUPALIGNMENT_BOTTOMLEFT;
+      mPopupAlignment = POPUPALIGNMENT_TOPLEFT;
+      mPosition = POPUPPOSITION_AFTERSTART;
+    }
+    else if (position.EqualsLiteral("after_end")) {
+      mPopupAnchor = POPUPALIGNMENT_BOTTOMRIGHT;
+      mPopupAlignment = POPUPALIGNMENT_TOPRIGHT;
+      mPosition = POPUPPOSITION_AFTEREND;
+    }
+    else if (position.EqualsLiteral("start_before")) {
+      mPopupAnchor = POPUPALIGNMENT_TOPLEFT;
+      mPopupAlignment = POPUPALIGNMENT_TOPRIGHT;
+      mPosition = POPUPPOSITION_STARTBEFORE;
+    }
+    else if (position.EqualsLiteral("start_after")) {
+      mPopupAnchor = POPUPALIGNMENT_BOTTOMLEFT;
+      mPopupAlignment = POPUPALIGNMENT_BOTTOMRIGHT;
+      mPosition = POPUPPOSITION_STARTAFTER;
+    }
+    else if (position.EqualsLiteral("end_before")) {
+      mPopupAnchor = POPUPALIGNMENT_TOPRIGHT;
+      mPopupAlignment = POPUPALIGNMENT_TOPLEFT;
+      mPosition = POPUPPOSITION_ENDBEFORE;
+    }
+    else if (position.EqualsLiteral("end_after")) {
+      mPopupAnchor = POPUPALIGNMENT_BOTTOMRIGHT;
+      mPopupAlignment = POPUPALIGNMENT_BOTTOMLEFT;
+      mPosition = POPUPPOSITION_ENDAFTER;
+    }
+    else if (position.EqualsLiteral("overlap")) {
+      mPopupAnchor = POPUPALIGNMENT_TOPLEFT;
+      mPopupAlignment = POPUPALIGNMENT_TOPLEFT;
+      mPosition = POPUPPOSITION_OVERLAP;
+    }
+    else if (position.EqualsLiteral("after_pointer")) {
+      mPopupAnchor = POPUPALIGNMENT_TOPLEFT;
+      mPopupAlignment = POPUPALIGNMENT_TOPLEFT;
+      mPosition = POPUPPOSITION_AFTERPOINTER;
+      // XXXndeakin this is supposed to anchor vertically after, but with the
+      // horizontal position as the mouse pointer.
+      mYPos += 21;
+    }
+    else if (position.EqualsLiteral("selection")) {
+      mPopupAnchor = POPUPALIGNMENT_BOTTOMLEFT;
+      mPopupAlignment = POPUPALIGNMENT_TOPLEFT;
+      mPosition = POPUPPOSITION_SELECTION;
+    }
+    else {
+      InitPositionFromAnchorAlign(anchor, align);
+    }
+  }
+
+  mScreenRect = nsIntRect(-1, -1, 0, 0);
+
+  if (aAttributesOverride) {
+    // Use |left| and |top| dimension attributes to position the popup if
+    // present, as they may have been persisted. 
+    nsAutoString left, top;
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::left, left);
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::top, top);
+
+    nsresult err;
+    if (!left.IsEmpty()) {
+      int32_t x = left.ToInteger(&err);
+      if (NS_SUCCEEDED(err))
+        mScreenRect.x = x;
+    }
+    if (!top.IsEmpty()) {
+      int32_t y = top.ToInteger(&err);
+      if (NS_SUCCEEDED(err))
+        mScreenRect.y = y;
+    }
+  }
+}
+
+void
+nsMenuPopupFrame::InitializePopupAtScreen(nsIContent* aTriggerContent,
+                                          int32_t aXPos, int32_t aYPos,
+                                          bool aIsContextMenu)
+{
+  EnsureWidget();
+
+  mPopupState = ePopupShowing;
+  mAnchorContent = nullptr;
+  mTriggerContent = aTriggerContent;
+  mScreenRect = nsIntRect(aXPos, aYPos, 0, 0);
+  mXPos = 0;
+  mYPos = 0;
+  mFlip = FlipType_Default;
+  mPopupAnchor = POPUPALIGNMENT_NONE;
+  mPopupAlignment = POPUPALIGNMENT_NONE;
+  mPosition = POPUPPOSITION_UNKNOWN;
+  mIsContextMenu = aIsContextMenu;
+  mAdjustOffsetForContextMenu = aIsContextMenu;
+  mAnchorType = MenuPopupAnchorType_Point;
+}
+
+void
+nsMenuPopupFrame::InitializePopupAtRect(nsIContent* aTriggerContent,
+                                        const nsAString& aPosition,
+                                        const nsIntRect& aRect,
+                                        bool aAttributesOverride)
+{
+  InitializePopup(nullptr, aTriggerContent, aPosition, 0, 0,
+                  MenuPopupAnchorType_Rect, aAttributesOverride);
+  mScreenRect = aRect;
+}
+
+void
+nsMenuPopupFrame::InitializePopupWithAnchorAlign(nsIContent* aAnchorContent,
+                                                 nsAString& aAnchor,
+                                                 nsAString& aAlign,
+                                                 int32_t aXPos, int32_t aYPos)
+{
+  EnsureWidget();
+
+  mPopupState = ePopupShowing;
+  mAdjustOffsetForContextMenu = false;
+  mFlip = FlipType_Default;
+
+  // this popup opening function is provided for backwards compatibility
+  // only. It accepts either coordinates or an anchor and alignment value
+  // but doesn't use both together.
+  if (aXPos == -1 && aYPos == -1) {
+    mAnchorContent = aAnchorContent;
+    mAnchorType = MenuPopupAnchorType_Node;
+    mScreenRect = nsIntRect(-1, -1, 0, 0);
+    mXPos = 0;
+    mYPos = 0;
+    InitPositionFromAnchorAlign(aAnchor, aAlign);
+  }
+  else {
+    mAnchorContent = nullptr;
+    mAnchorType = MenuPopupAnchorType_Point;
+    mPopupAnchor = POPUPALIGNMENT_NONE;
+    mPopupAlignment = POPUPALIGNMENT_NONE;
+    mPosition = POPUPPOSITION_UNKNOWN;
+    mScreenRect = nsIntRect(aXPos, aYPos, 0, 0);
+    mXPos = aXPos;
+    mYPos = aYPos;
+  }
+}
+
+void
+nsMenuPopupFrame::ShowPopup(bool aIsContextMenu)
+{
+  mIsContextMenu = aIsContextMenu;
+
+  InvalidateFrameSubtree();
+
+  if (mPopupState == ePopupShowing || mPopupState == ePopupPositioning) {
+    mPopupState = ePopupOpening;
+    mIsOpenChanged = true;
+
+    // Clear mouse capture when a popup is opened.
+    if (mPopupType == ePopupTypeMenu) {
+      EventStateManager* activeESM =
+        static_cast<EventStateManager*>(
+          EventStateManager::GetActiveEventStateManager());
+      if (activeESM) {
+        EventStateManager::ClearGlobalActiveContent(activeESM);
+      }
+
+      nsIPresShell::SetCapturingContent(nullptr, 0);
+    }
+
+    nsMenuFrame* menuFrame = do_QueryFrame(GetParent());
+    if (menuFrame) {
+      nsWeakFrame weakFrame(this);
+      menuFrame->PopupOpened();
+      if (!weakFrame.IsAlive())
+        return;
+    }
+
+    // do we need an actual reflow here?
+    // is SetPopupPosition all that is needed?
+    PresContext()->PresShell()->FrameNeedsReflow(this, nsIPresShell::eTreeChange,
+                                                 NS_FRAME_HAS_DIRTY_CHILDREN);
+
+    if (mPopupType == ePopupTypeMenu) {
+      nsCOMPtr<nsISound> sound(do_CreateInstance("@mozilla.org/sound;1"));
+      if (sound)
+        sound->PlayEventSound(nsISound::EVENT_MENU_POPUP);
+    }
+  }
+
+  mShouldAutoPosition = true;
+}
+
+void
+nsMenuPopupFrame::HidePopup(bool aDeselectMenu, nsPopupState aNewState)
+{
+  NS_ASSERTION(aNewState == ePopupClosed || aNewState == ePopupInvisible,
+               "popup being set to unexpected state");
+
+  ClearPopupShownDispatcher();
+
+  // don't hide the popup when it isn't open
+  if (mPopupState == ePopupClosed || mPopupState == ePopupShowing ||
+      mPopupState == ePopupPositioning)
+    return;
+
+  // clear the trigger content if the popup is being closed. But don't clear
+  // it if the popup is just being made invisible as a popuphiding or command
+  // event may want to retrieve it.
+  if (aNewState == ePopupClosed) {
+    // if the popup had a trigger node set, clear the global window popup node
+    // as well
+    if (mTriggerContent) {
+      nsIDocument* doc = mContent->GetUncomposedDoc();
+      if (doc) {
+        if (nsPIDOMWindowOuter* win = doc->GetWindow()) {
+          nsCOMPtr<nsPIWindowRoot> root = win->GetTopWindowRoot();
+          if (root) {
+            root->SetPopupNode(nullptr);
+          }
+        }
+      }
+    }
+    mTriggerContent = nullptr;
+    mAnchorContent = nullptr;
+  }
+
+  // when invisible and about to be closed, HidePopup has already been called,
+  // so just set the new state to closed and return
+  if (mPopupState == ePopupInvisible) {
+    if (aNewState == ePopupClosed)
+      mPopupState = ePopupClosed;
+    return;
+  }
+
+  mPopupState = aNewState;
+
+  if (IsMenu())
+    SetCurrentMenuItem(nullptr);
+
+  mIncrementalString.Truncate();
+
+  LockMenuUntilClosed(false);
+
+  mIsOpenChanged = false;
+  mCurrentMenu = nullptr; // make sure no current menu is set
+  mHFlip = mVFlip = false;
+
+  nsView* view = GetView();
+  nsViewManager* viewManager = view->GetViewManager();
+  viewManager->SetViewVisibility(view, nsViewVisibility_kHide);
+
+  FireDOMEvent(NS_LITERAL_STRING("DOMMenuInactive"), mContent);
+
+  // XXX, bug 137033, In Windows, if mouse is outside the window when the menupopup closes, no
+  // mouse_enter/mouse_exit event will be fired to clear current hover state, we should clear it manually.
+  // This code may not the best solution, but we can leave it here until we find the better approach.
+  NS_ASSERTION(mContent->IsElement(), "How do we have a non-element?");
+  EventStates state = mContent->AsElement()->State();
+
+  if (state.HasState(NS_EVENT_STATE_HOVER)) {
+    EventStateManager* esm = PresContext()->EventStateManager();
+    esm->SetContentState(nullptr, NS_EVENT_STATE_HOVER);
+  }
+
+  nsMenuFrame* menuFrame = do_QueryFrame(GetParent());
+  if (menuFrame) {
+    menuFrame->PopupClosed(aDeselectMenu);
+  }
+}
+
+uint32_t
+nsMenuPopupFrame::GetXULLayoutFlags()
+{
+  return NS_FRAME_NO_SIZE_VIEW | NS_FRAME_NO_MOVE_VIEW | NS_FRAME_NO_VISIBILITY;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// GetRootViewForPopup
+//   Retrieves the view for the popup widget that contains the given frame. 
+//   If the given frame is not contained by a popup widget, return the
+//   root view of the root viewmanager.
+nsView*
+nsMenuPopupFrame::GetRootViewForPopup(nsIFrame* aStartFrame)
+{
+  nsView* view = aStartFrame->GetClosestView();
+  NS_ASSERTION(view, "frame must have a closest view!");
+  while (view) {
+    // Walk up the view hierarchy looking for a view whose widget has a 
+    // window type of eWindowType_popup - in other words a popup window
+    // widget. If we find one, this is the view we want. 
+    nsIWidget* widget = view->GetWidget();
+    if (widget && widget->WindowType() == eWindowType_popup) {
+      return view;
+    }
+
+    nsView* temp = view->GetParent();
+    if (!temp) {
+      // Otherwise, we've walked all the way up to the root view and not
+      // found a view for a popup window widget. Just return the root view.
+      return view;
+    }
+    view = temp;
+  }
+
+  return nullptr;
+}
+
+nsPoint
+nsMenuPopupFrame::AdjustPositionForAnchorAlign(nsRect& anchorRect,
+                                               FlipStyle& aHFlip, FlipStyle& aVFlip)
+{
+  // flip the anchor and alignment for right-to-left
+  int8_t popupAnchor(mPopupAnchor);
+  int8_t popupAlign(mPopupAlignment);
+  if (IsDirectionRTL()) {
+    // no need to flip the centered anchor types vertically
+    if (popupAnchor <= POPUPALIGNMENT_LEFTCENTER) {
+      popupAnchor = -popupAnchor;
+    }
+    popupAlign = -popupAlign;
+  }
+
+  nsRect originalAnchorRect(anchorRect);
+
+  // first, determine at which corner of the anchor the popup should appear
+  nsPoint pnt;
+  switch (popupAnchor) {
+    case POPUPALIGNMENT_LEFTCENTER:
+      pnt = nsPoint(anchorRect.x, anchorRect.y + anchorRect.height / 2);
+      anchorRect.y = pnt.y;
+      anchorRect.height = 0;
+      break;
+    case POPUPALIGNMENT_RIGHTCENTER:
+      pnt = nsPoint(anchorRect.XMost(), anchorRect.y + anchorRect.height / 2);
+      anchorRect.y = pnt.y;
+      anchorRect.height = 0;
+      break;
+    case POPUPALIGNMENT_TOPCENTER:
+      pnt = nsPoint(anchorRect.x + anchorRect.width / 2, anchorRect.y);
+      anchorRect.x = pnt.x;
+      anchorRect.width = 0;
+      break;
+    case POPUPALIGNMENT_BOTTOMCENTER:
+      pnt = nsPoint(anchorRect.x + anchorRect.width / 2, anchorRect.YMost());
+      anchorRect.x = pnt.x;
+      anchorRect.width = 0;
+      break;
+    case POPUPALIGNMENT_TOPRIGHT:
+      pnt = anchorRect.TopRight();
+      break;
+    case POPUPALIGNMENT_BOTTOMLEFT:
+      pnt = anchorRect.BottomLeft();
+      break;
+    case POPUPALIGNMENT_BOTTOMRIGHT:
+      pnt = anchorRect.BottomRight();
+      break;
+    case POPUPALIGNMENT_TOPLEFT:
+    default:
+      pnt = anchorRect.TopLeft();
+      break;
+  }
+
+  // If the alignment is on the right edge of the popup, move the popup left
+  // by the width. Similarly, if the alignment is on the bottom edge of the
+  // popup, move the popup up by the height. In addition, account for the
+  // margins of the popup on the edge on which it is aligned.
+  nsMargin margin(0, 0, 0, 0);
+  StyleMargin()->GetMargin(margin);
+  switch (popupAlign) {
+    case POPUPALIGNMENT_TOPRIGHT:
+      pnt.MoveBy(-mRect.width - margin.right, margin.top);
+      break;
+    case POPUPALIGNMENT_BOTTOMLEFT:
+      pnt.MoveBy(margin.left, -mRect.height - margin.bottom);
+      break;
+    case POPUPALIGNMENT_BOTTOMRIGHT:
+      pnt.MoveBy(-mRect.width - margin.right, -mRect.height - margin.bottom);
+      break;
+    case POPUPALIGNMENT_TOPLEFT:
+    default:
+      pnt.MoveBy(margin.left, margin.top);
+      break;
+  }
+
+  // If we aligning to the selected item in the popup, adjust the vertical
+  // position by the height of the menulist label and the selected item's
+  // position.
+  if (mPosition == POPUPPOSITION_SELECTION) {
+    MOZ_ASSERT(popupAnchor == POPUPALIGNMENT_BOTTOMLEFT ||
+              popupAnchor == POPUPALIGNMENT_BOTTOMRIGHT);
+    MOZ_ASSERT(popupAlign == POPUPALIGNMENT_TOPLEFT ||
+               popupAlign == POPUPALIGNMENT_TOPRIGHT);
+
+    nsIFrame* selectedItemFrame = GetSelectedItemForAlignment();
+    if (selectedItemFrame) {
+      pnt.y -= originalAnchorRect.height + selectedItemFrame->GetRect().y;
+    }
+  }
+
+  // Flipping horizontally is allowed as long as the popup is above or below
+  // the anchor. This will happen if both the anchor and alignment are top or
+  // both are bottom, but different values. Similarly, flipping vertically is
+  // allowed if the popup is to the left or right of the anchor. In this case,
+  // the values of the constants are such that both must be positive or both
+  // must be negative. A special case, used for overlap, allows flipping
+  // vertically as well.
+  // If we are flipping in both directions, we want to set a flip style both
+  // horizontally and vertically. However, we want to flip on the inside edge
+  // of the anchor. Consider the example of a typical dropdown menu.
+  // Vertically, we flip the popup on the outside edges of the anchor menu,
+  // however horizontally, we want to to use the inside edges so the popup
+  // still appears underneath the anchor menu instead of floating off the
+  // side of the menu.
+  switch (popupAnchor) {
+    case POPUPALIGNMENT_LEFTCENTER:
+    case POPUPALIGNMENT_RIGHTCENTER:
+      aHFlip = FlipStyle_Outside;
+      aVFlip = FlipStyle_Inside;
+      break;
+    case POPUPALIGNMENT_TOPCENTER:
+    case POPUPALIGNMENT_BOTTOMCENTER:
+      aHFlip = FlipStyle_Inside;
+      aVFlip = FlipStyle_Outside;
+      break;
+    default:
+    {
+      FlipStyle anchorEdge = mFlip == FlipType_Both ? FlipStyle_Inside : FlipStyle_None;
+      aHFlip = (popupAnchor == -popupAlign) ? FlipStyle_Outside : anchorEdge;
+      if (((popupAnchor > 0) == (popupAlign > 0)) ||
+          (popupAnchor == POPUPALIGNMENT_TOPLEFT && popupAlign == POPUPALIGNMENT_TOPLEFT))
+        aVFlip = FlipStyle_Outside;
+      else
+        aVFlip = anchorEdge;
+      break;
+    }
+  }
+
+  return pnt;
+}
+
+nsIFrame* nsMenuPopupFrame::GetSelectedItemForAlignment()
+{
+  // This method adjusts a menulist's popup such that the selected item is under the cursor, aligned
+  // with the menulist label.
+  nsCOMPtr<nsIDOMXULSelectControlElement> select = do_QueryInterface(mAnchorContent);
+  if (!select) {
+    // If there isn't an anchor, then try just getting the parent of the popup.
+    select = do_QueryInterface(mContent->GetParent());
+    if (!select) {
+      return nullptr;
+    }
+  }
+
+  nsCOMPtr<nsIDOMXULSelectControlItemElement> item;
+  select->GetSelectedItem(getter_AddRefs(item));
+
+  nsCOMPtr<nsIContent> selectedElement = do_QueryInterface(item);
+  return selectedElement ? selectedElement->GetPrimaryFrame() : nullptr;
+}
+
+nscoord
+nsMenuPopupFrame::SlideOrResize(nscoord& aScreenPoint, nscoord aSize,
+                               nscoord aScreenBegin, nscoord aScreenEnd,
+                               nscoord *aOffset)
+{
+  // The popup may be positioned such that either the left/top or bottom/right
+  // is outside the screen - but never both.
+  nscoord newPos =
+    std::max(aScreenBegin, std::min(aScreenEnd - aSize, aScreenPoint));
+  *aOffset = newPos - aScreenPoint;
+  aScreenPoint = newPos;
+  return std::min(aSize, aScreenEnd - aScreenPoint);
+}
+
+nscoord
+nsMenuPopupFrame::FlipOrResize(nscoord& aScreenPoint, nscoord aSize, 
+                               nscoord aScreenBegin, nscoord aScreenEnd,
+                               nscoord aAnchorBegin, nscoord aAnchorEnd,
+                               nscoord aMarginBegin, nscoord aMarginEnd,
+                               nscoord aOffsetForContextMenu, FlipStyle aFlip,
+                               bool aEndAligned, bool* aFlipSide)
+{
+  // The flip side argument will be set to true if there wasn't room and we
+  // flipped to the opposite side.
+  *aFlipSide = false;
+
+  // all of the coordinates used here are in app units relative to the screen
+  nscoord popupSize = aSize;
+  if (aScreenPoint < aScreenBegin) {
+    // at its current position, the popup would extend past the left or top
+    // edge of the screen, so it will have to be moved or resized.
+    if (aFlip) {
+      // for inside flips, we flip on the opposite side of the anchor
+      nscoord startpos = aFlip == FlipStyle_Outside ? aAnchorBegin : aAnchorEnd;
+      nscoord endpos = aFlip == FlipStyle_Outside ? aAnchorEnd : aAnchorBegin;
+
+      // check whether there is more room to the left and right (or top and
+      // bottom) of the anchor and put the popup on the side with more room.
+      if (startpos - aScreenBegin >= aScreenEnd - endpos) {
+        aScreenPoint = aScreenBegin;
+        popupSize = startpos - aScreenPoint - aMarginEnd;
+        *aFlipSide = !aEndAligned;
+      }
+      else {
+        // If the newly calculated position is different than the existing
+        // position, flip such that the popup is to the right or bottom of the
+        // anchor point instead . However, when flipping use the same margin
+        // size.
+        nscoord newScreenPoint = endpos + aMarginEnd;
+        if (newScreenPoint != aScreenPoint) {
+          *aFlipSide = aEndAligned;
+          aScreenPoint = newScreenPoint;
+          // check if the new position is still off the right or bottom edge of
+          // the screen. If so, resize the popup.
+          if (aScreenPoint + aSize > aScreenEnd) {
+            popupSize = aScreenEnd - aScreenPoint;
+          }
+        }
+      }
+    }
+    else {
+      aScreenPoint = aScreenBegin;
+    }
+  }
+  else if (aScreenPoint + aSize > aScreenEnd) {
+    // at its current position, the popup would extend past the right or
+    // bottom edge of the screen, so it will have to be moved or resized.
+    if (aFlip) {
+      // for inside flips, we flip on the opposite side of the anchor
+      nscoord startpos = aFlip == FlipStyle_Outside ? aAnchorBegin : aAnchorEnd;
+      nscoord endpos = aFlip == FlipStyle_Outside ? aAnchorEnd : aAnchorBegin;
+
+      // check whether there is more room to the left and right (or top and
+      // bottom) of the anchor and put the popup on the side with more room.
+      if (aScreenEnd - endpos >= startpos - aScreenBegin) {
+        *aFlipSide = aEndAligned;
+        if (mIsContextMenu) {
+          aScreenPoint = aScreenEnd - aSize;
+        }
+        else {
+          aScreenPoint = endpos + aMarginBegin;
+          popupSize = aScreenEnd - aScreenPoint;
+        }
+      }
+      else {
+        // if the newly calculated position is different than the existing
+        // position, we flip such that the popup is to the left or top of the
+        // anchor point instead.
+        nscoord newScreenPoint = startpos - aSize - aMarginBegin - std::max(aOffsetForContextMenu, 0);
+        if (newScreenPoint != aScreenPoint) {
+          *aFlipSide = !aEndAligned;
+          aScreenPoint = newScreenPoint;
+
+          // check if the new position is still off the left or top edge of the
+          // screen. If so, resize the popup.
+          if (aScreenPoint < aScreenBegin) {
+            aScreenPoint = aScreenBegin;
+            if (!mIsContextMenu) {
+              popupSize = startpos - aScreenPoint - aMarginBegin;
+            }
+          }
+        }
+      }
+    }
+    else {
+      aScreenPoint = aScreenEnd - aSize;
+    }
+  }
+
+  // Make sure that the point is within the screen boundaries and that the
+  // size isn't off the edge of the screen. This can happen when a large
+  // positive or negative margin is used.
+  if (aScreenPoint < aScreenBegin) {
+    aScreenPoint = aScreenBegin;
+  }
+  if (aScreenPoint > aScreenEnd) {
+    aScreenPoint = aScreenEnd - aSize;
+  }
+
+  // If popupSize ended up being negative, or the original size was actually
+  // smaller than the calculated popup size, just use the original size instead.
+  if (popupSize <= 0 || aSize < popupSize) {
+    popupSize = aSize;
+  }
+  return std::min(popupSize, aScreenEnd - aScreenPoint);
+}
+
+nsresult
+nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame, bool aIsMove, bool aSizedToPopup, bool aNotify)
+{
+  if (!mShouldAutoPosition)
+    return NS_OK;
+
+  // If this is due to a move, return early if the popup hasn't been laid out
+  // yet. On Windows, this can happen when using a drag popup before it opens.
+  if (aIsMove && (mPrefSize.width == -1 || mPrefSize.height == -1)) {
+    return NS_OK;
+  }
+
+  nsPresContext* presContext = PresContext();
+  nsIFrame* rootFrame = presContext->PresShell()->FrameManager()->GetRootFrame();
+  NS_ASSERTION(rootFrame->GetView() && GetView() &&
+               rootFrame->GetView() == GetView()->GetParent(),
+               "rootFrame's view is not our view's parent???");
+
+  // For anchored popups, the anchor rectangle. For non-anchored popups, the
+  // size will be 0.
+  nsRect anchorRect;
+
+  // Width of the parent, used when aSizedToPopup is true.
+  int32_t parentWidth = 0;
+
+  bool anchored = IsAnchored();
+  if (anchored || aSizedToPopup) {
+    // In order to deal with transforms, we need the root prescontext:
+    nsPresContext* rootPresContext = presContext->GetRootPresContext();
+
+    // If we can't reach a root pres context, don't bother continuing:
+    if (!rootPresContext) {
+      return NS_OK;
+    }
+
+    // If anchored to a rectangle, use that rectangle. Otherwise, determine the
+    // rectangle from the anchor.
+    if (mAnchorType == MenuPopupAnchorType_Rect) {
+      anchorRect = ToAppUnits(mScreenRect, presContext->AppUnitsPerCSSPixel());
+    }
+    else {
+      // if the frame is not specified, use the anchor node passed to OpenPopup. If
+      // that wasn't specified either, use the root frame. Note that mAnchorContent
+      // might be a different document so its presshell must be used.
+      if (!aAnchorFrame) {
+        if (mAnchorContent) {
+          aAnchorFrame = mAnchorContent->GetPrimaryFrame();
+        }
+
+        if (!aAnchorFrame) {
+          aAnchorFrame = rootFrame;
+          if (!aAnchorFrame)
+            return NS_OK;
+        }
+      }
+
+      // And then we need its root frame for a reference
+      nsIFrame* referenceFrame = rootPresContext->FrameManager()->GetRootFrame();
+
+      // the dimensions of the anchor
+      nsRect parentRect = aAnchorFrame->GetRectRelativeToSelf();
+      // Relative to the root
+      anchorRect = nsLayoutUtils::TransformFrameRectToAncestor(aAnchorFrame,
+                                                               parentRect,
+                                                               referenceFrame);
+      // Relative to the screen
+      anchorRect.MoveBy(referenceFrame->GetScreenRectInAppUnits().TopLeft());
+
+      // In its own app units
+      anchorRect =
+        anchorRect.ScaleToOtherAppUnitsRoundOut(rootPresContext->AppUnitsPerDevPixel(),
+                                                presContext->AppUnitsPerDevPixel());
+    }
+
+    // The width is needed when aSizedToPopup is true
+    parentWidth = anchorRect.width;
+  }
+
+  // Set the popup's size to the preferred size. Below, this size will be
+  // adjusted to fit on the screen or within the content area. If the anchor
+  // is sized to the popup, use the anchor's width instead of the preferred
+  // width. The preferred size should already be set by the parent frame.
+  NS_ASSERTION(mPrefSize.width >= 0 || mPrefSize.height >= 0,
+               "preferred size of popup not set");
+  mRect.width = aSizedToPopup ? parentWidth : mPrefSize.width;
+  mRect.height = mPrefSize.height;
+
+  // If we're anchoring to a rect, and the rect is smaller than the preferred size
+  // of the popup, change its width accordingly.
+  if (mAnchorType == MenuPopupAnchorType_Rect &&
+      parentWidth < mPrefSize.width) {
+    mRect.width = mPrefSize.width;
+  }
+
+  // the screen position in app units where the popup should appear
+  nsPoint screenPoint;
+
+  // indicators of whether the popup should be flipped or resized.
+  FlipStyle hFlip = FlipStyle_None, vFlip = FlipStyle_None;
+
+  nsMargin margin(0, 0, 0, 0);
+  StyleMargin()->GetMargin(margin);
+
+  // the screen rectangle of the root frame, in dev pixels.
+  nsRect rootScreenRect = rootFrame->GetScreenRectInAppUnits();
+
+  nsDeviceContext* devContext = presContext->DeviceContext();
+  nsPoint offsetForContextMenu;
+
+  bool isNoAutoHide = IsNoAutoHide();
+  nsPopupLevel popupLevel = PopupLevel(isNoAutoHide);
+
+  if (anchored) {
+    // if we are anchored, there are certain things we don't want to do when
+    // repositioning the popup to fit on the screen, such as end up positioned
+    // over the anchor, for instance a popup appearing over the menu label.
+    // When doing this reposition, we want to move the popup to the side with
+    // the most room. The combination of anchor and alignment dictate if we 
+    // readjust above/below or to the left/right.
+    if (mAnchorContent || mAnchorType == MenuPopupAnchorType_Rect) {
+      // move the popup according to the anchor and alignment. This will also
+      // tell us which axis the popup is flush against in case we have to move
+      // it around later. The AdjustPositionForAnchorAlign method accounts for
+      // the popup's margin.
+      screenPoint = AdjustPositionForAnchorAlign(anchorRect, hFlip, vFlip);
+    }
+    else {
+      // with no anchor, the popup is positioned relative to the root frame
+      anchorRect = rootScreenRect;
+      screenPoint = anchorRect.TopLeft() + nsPoint(margin.left, margin.top);
+    }
+
+    // mXPos and mYPos specify an additonal offset passed to OpenPopup that
+    // should be added to the position.  We also add the offset to the anchor
+    // pos so a later flip/resize takes the offset into account.
+    nscoord anchorXOffset = presContext->CSSPixelsToAppUnits(mXPos);
+    if (IsDirectionRTL()) {
+      screenPoint.x -= anchorXOffset;
+      anchorRect.x -= anchorXOffset;
+    } else {
+      screenPoint.x += anchorXOffset;
+      anchorRect.x += anchorXOffset;
+    }
+    nscoord anchorYOffset = presContext->CSSPixelsToAppUnits(mYPos);
+    screenPoint.y += anchorYOffset;
+    anchorRect.y += anchorYOffset;
+
+    // If this is a noautohide popup, set the screen coordinates of the popup.
+    // This way, the popup stays at the location where it was opened even when
+    // the window is moved. Popups at the parent level follow the parent
+    // window as it is moved and remained anchored, so we want to maintain the
+    // anchoring instead.
+    if (isNoAutoHide &&
+        (popupLevel != ePopupLevelParent || mAnchorType == MenuPopupAnchorType_Rect)) {
+      // Account for the margin that will end up being added to the screen coordinate
+      // the next time SetPopupPosition is called.
+      mAnchorType = MenuPopupAnchorType_Point;
+      mScreenRect.x = presContext->AppUnitsToIntCSSPixels(screenPoint.x - margin.left);
+      mScreenRect.y = presContext->AppUnitsToIntCSSPixels(screenPoint.y - margin.top);
+    }
+  }
+  else {
+    // The popup is positioned at a screen coordinate.
+    // First convert the screen position in mScreenRect from CSS pixels into
+    // device pixels, ignoring any zoom as mScreenRect holds unzoomed screen
+    // coordinates.
+    int32_t factor = devContext->AppUnitsPerDevPixelAtUnitFullZoom();
+
+    // Depending on the platform, context menus should be offset by varying amounts
+    // to ensure that they don't appear directly where the cursor is. Otherwise,
+    // it is too easy to have the context menu close up again.
+    if (mAdjustOffsetForContextMenu) {
+      nsPoint offsetForContextMenuDev;
+      offsetForContextMenuDev.x = nsPresContext::CSSPixelsToAppUnits(LookAndFeel::GetInt(
+                                    LookAndFeel::eIntID_ContextMenuOffsetHorizontal)) / factor;
+      offsetForContextMenuDev.y = nsPresContext::CSSPixelsToAppUnits(LookAndFeel::GetInt(
+                                    LookAndFeel::eIntID_ContextMenuOffsetVertical)) / factor;
+      offsetForContextMenu.x = presContext->DevPixelsToAppUnits(offsetForContextMenuDev.x);
+      offsetForContextMenu.y = presContext->DevPixelsToAppUnits(offsetForContextMenuDev.y);
+    }
+
+    // next, convert into app units accounting for the zoom
+    screenPoint.x = presContext->DevPixelsToAppUnits(
+                      nsPresContext::CSSPixelsToAppUnits(mScreenRect.x) / factor);
+    screenPoint.y = presContext->DevPixelsToAppUnits(
+                      nsPresContext::CSSPixelsToAppUnits(mScreenRect.y) / factor);
+    anchorRect = nsRect(screenPoint, nsSize(0, 0));
+
+    // add the margins on the popup
+    screenPoint.MoveBy(margin.left + offsetForContextMenu.x,
+                       margin.top + offsetForContextMenu.y);
+
+#ifdef XP_MACOSX
+    // OSX tooltips follow standard flip rule but other popups flip horizontally not vertically
+    if (mPopupType == ePopupTypeTooltip) {
+        vFlip = FlipStyle_Outside;
+    } else {
+        hFlip = FlipStyle_Outside;
+    }
+#else
+    // Other OS screen positioned popups can be flipped vertically but never horizontally
+    vFlip = FlipStyle_Outside;
+#endif // #ifdef XP_MACOSX
+  }
+
+  // If a panel is being moved or has flip="none", don't constrain or flip it. But always do this for
+  // content shells, so that the popup doesn't extend outside the containing frame.
+  if (mInContentShell || (mFlip != FlipType_None &&
+                          (!aIsMove || mPopupType != ePopupTypePanel))) {
+    int32_t appPerDev = presContext->AppUnitsPerDevPixel();
+    LayoutDeviceIntRect anchorRectDevPix =
+      LayoutDeviceIntRect::FromAppUnitsToNearest(anchorRect, appPerDev);
+    LayoutDeviceIntRect rootScreenRectDevPix =
+      LayoutDeviceIntRect::FromAppUnitsToNearest(rootScreenRect, appPerDev);
+    LayoutDeviceIntRect screenRectDevPix =
+      GetConstraintRect(anchorRectDevPix, rootScreenRectDevPix, popupLevel);
+    nsRect screenRect =
+      LayoutDeviceIntRect::ToAppUnits(screenRectDevPix, appPerDev);
+
+    // Ensure that anchorRect is on screen.
+    anchorRect = anchorRect.Intersect(screenRect);
+
+    // shrink the the popup down if it is larger than the screen size
+    if (mRect.width > screenRect.width)
+      mRect.width = screenRect.width;
+    if (mRect.height > screenRect.height)
+      mRect.height = screenRect.height;
+
+    // at this point the anchor (anchorRect) is within the available screen
+    // area (screenRect) and the popup is known to be no larger than the screen.
+
+    // We might want to "slide" an arrow if the panel is of the correct type -
+    // but we can only slide on one axis - the other axis must be "flipped or
+    // resized" as normal.
+    bool slideHorizontal = false, slideVertical = false;
+    if (mFlip == FlipType_Slide) {
+      int8_t position = GetAlignmentPosition();
+      slideHorizontal = position >= POPUPPOSITION_BEFORESTART &&
+                        position <= POPUPPOSITION_AFTEREND;
+      slideVertical = position >= POPUPPOSITION_STARTBEFORE &&
+                      position <= POPUPPOSITION_ENDAFTER;
+    }
+
+    // Next, check if there is enough space to show the popup at full size when
+    // positioned at screenPoint. If not, flip the popups to the opposite side
+    // of their anchor point, or resize them as necessary.
+    bool endAligned = IsDirectionRTL() ?
+      mPopupAlignment == POPUPALIGNMENT_TOPLEFT || mPopupAlignment == POPUPALIGNMENT_BOTTOMLEFT :
+      mPopupAlignment == POPUPALIGNMENT_TOPRIGHT || mPopupAlignment == POPUPALIGNMENT_BOTTOMRIGHT;
+    if (slideHorizontal) {
+      mRect.width = SlideOrResize(screenPoint.x, mRect.width, screenRect.x,
+                                  screenRect.XMost(), &mAlignmentOffset);
+    } else {
+      mRect.width = FlipOrResize(screenPoint.x, mRect.width, screenRect.x,
+                                 screenRect.XMost(), anchorRect.x, anchorRect.XMost(),
+                                 margin.left, margin.right, offsetForContextMenu.x, hFlip,
+                                 endAligned, &mHFlip);
+    }
+
+    endAligned = mPopupAlignment == POPUPALIGNMENT_BOTTOMLEFT ||
+                 mPopupAlignment == POPUPALIGNMENT_BOTTOMRIGHT;
+    if (slideVertical) {
+      mRect.height = SlideOrResize(screenPoint.y, mRect.height, screenRect.y,
+                                  screenRect.YMost(), &mAlignmentOffset);
+    } else {
+      mRect.height = FlipOrResize(screenPoint.y, mRect.height, screenRect.y,
+                                  screenRect.YMost(), anchorRect.y, anchorRect.YMost(),
+                                  margin.top, margin.bottom, offsetForContextMenu.y, vFlip,
+                                  endAligned, &mVFlip);
+    }
+
+    NS_ASSERTION(screenPoint.x >= screenRect.x && screenPoint.y >= screenRect.y &&
+                 screenPoint.x + mRect.width <= screenRect.XMost() &&
+                 screenPoint.y + mRect.height <= screenRect.YMost(),
+                 "Popup is offscreen");
+  }
+
+  // snap the popup's position in screen coordinates to device pixels,
+  // see bug 622507, bug 961431
+  screenPoint.x = presContext->RoundAppUnitsToNearestDevPixels(screenPoint.x);
+  screenPoint.y = presContext->RoundAppUnitsToNearestDevPixels(screenPoint.y);
+
+  // determine the x and y position of the view by subtracting the desired
+  // screen position from the screen position of the root frame.
+  nsPoint viewPoint = screenPoint - rootScreenRect.TopLeft();
+
+  nsView* view = GetView();
+  NS_ASSERTION(view, "popup with no view");
+
+  // Offset the position by the width and height of the borders and titlebar.
+  // Even though GetClientOffset should return (0, 0) when there is no
+  // titlebar or borders, we skip these calculations anyway for non-panels
+  // to save time since they will never have a titlebar.
+  nsIWidget* widget = view->GetWidget();
+  if (mPopupType == ePopupTypePanel && widget) {
+    mLastClientOffset = widget->GetClientOffset();
+    viewPoint.x += presContext->DevPixelsToAppUnits(mLastClientOffset.x);
+    viewPoint.y += presContext->DevPixelsToAppUnits(mLastClientOffset.y);
+  }
+
+  presContext->GetPresShell()->GetViewManager()->
+    MoveViewTo(view, viewPoint.x, viewPoint.y);
+
+  // Now that we've positioned the view, sync up the frame's origin.
+  nsBoxFrame::SetPosition(viewPoint - GetParent()->GetOffsetTo(rootFrame));
+
+  if (aSizedToPopup) {
+    nsBoxLayoutState state(PresContext());
+    // XXXndeakin can parentSize.width still extend outside?
+    SetXULBounds(state, mRect);
+  }
+
+  // If the popup is in the positioned state or if it is shown and the position
+  // or size changed, dispatch a popuppositioned event if the popup wants it.
+  nsIntRect newRect(screenPoint.x, screenPoint.y, mRect.width, mRect.height);
+  if (mPopupState == ePopupPositioning ||
+      (mPopupState == ePopupShown && !newRect.IsEqualEdges(mUsedScreenRect))) {
+    mUsedScreenRect = newRect;
+    if (aNotify) {
+      nsXULPopupPositionedEvent::DispatchIfNeeded(mContent, false, false);
+    }
+  }
+
+  return NS_OK;
+}
+
+/* virtual */ nsMenuFrame*
+nsMenuPopupFrame::GetCurrentMenuItem()
+{
+  return mCurrentMenu;
+}
+
+LayoutDeviceIntRect
+nsMenuPopupFrame::GetConstraintRect(const LayoutDeviceIntRect& aAnchorRect,
+                                    const LayoutDeviceIntRect& aRootScreenRect,
+                                    nsPopupLevel aPopupLevel)
+{
+  LayoutDeviceIntRect screenRectPixels;
+
+  // determine the available screen space. It will be reduced by the OS chrome
+  // such as menubars. It addition, for content shells, it will be the area of
+  // the content rather than the screen.
+  nsCOMPtr<nsIScreen> screen;
+  nsCOMPtr<nsIScreenManager> sm(do_GetService("@mozilla.org/gfx/screenmanager;1"));
+  if (sm) {
+    // for content shells, get the screen where the root frame is located.
+    // This is because we need to constrain the content to this content area,
+    // so we should use the same screen. Otherwise, use the screen where the
+    // anchor is located.
+    DesktopToLayoutDeviceScale scale =
+      PresContext()->DeviceContext()->GetDesktopToDeviceScale();
+    DesktopRect rect =
+      (mInContentShell ? aRootScreenRect : aAnchorRect) / scale;
+    int32_t width = std::max(1, NSToIntRound(rect.width));
+    int32_t height = std::max(1, NSToIntRound(rect.height));
+    sm->ScreenForRect(rect.x, rect.y, width, height, getter_AddRefs(screen));
+    if (screen) {
+      // Non-top-level popups (which will always be panels)
+      // should never overlap the OS bar:
+      bool dontOverlapOSBar = aPopupLevel != ePopupLevelTop;
+      // get the total screen area if the popup is allowed to overlap it.
+      if (!dontOverlapOSBar && mMenuCanOverlapOSBar && !mInContentShell)
+        screen->GetRect(&screenRectPixels.x, &screenRectPixels.y,
+          &screenRectPixels.width, &screenRectPixels.height);
+      else
+        screen->GetAvailRect(&screenRectPixels.x, &screenRectPixels.y,
+          &screenRectPixels.width, &screenRectPixels.height);
+    }
+  }
+
+  if (mInContentShell) {
+    // for content shells, clip to the client area rather than the screen area
+    screenRectPixels.IntersectRect(screenRectPixels, aRootScreenRect);
+  }
+  else if (!mOverrideConstraintRect.IsEmpty()) {
+    LayoutDeviceIntRect overrideConstrainRect =
+      LayoutDeviceIntRect::FromAppUnitsToNearest(mOverrideConstraintRect,
+                                                 PresContext()->AppUnitsPerDevPixel());
+    // This is currently only used for <select> elements where we want to constrain
+    // vertically to the screen but not horizontally, so do the intersection and then
+    // reset the horizontal values.
+    screenRectPixels.IntersectRect(screenRectPixels, overrideConstrainRect);
+    screenRectPixels.x = overrideConstrainRect.x;
+    screenRectPixels.width = overrideConstrainRect.width;
+  }
+
+  return screenRectPixels;
+}
+
+void nsMenuPopupFrame::CanAdjustEdges(int8_t aHorizontalSide,
+                                      int8_t aVerticalSide,
+                                      LayoutDeviceIntPoint& aChange)
+{
+  int8_t popupAlign(mPopupAlignment);
+  if (IsDirectionRTL()) {
+    popupAlign = -popupAlign;
+  }
+
+  if (aHorizontalSide == (mHFlip ? NS_SIDE_RIGHT : NS_SIDE_LEFT)) {
+    if (popupAlign == POPUPALIGNMENT_TOPLEFT || popupAlign == POPUPALIGNMENT_BOTTOMLEFT) {
+      aChange.x = 0;
+    }
+  }
+  else if (aHorizontalSide == (mHFlip ? NS_SIDE_LEFT : NS_SIDE_RIGHT)) {
+    if (popupAlign == POPUPALIGNMENT_TOPRIGHT || popupAlign == POPUPALIGNMENT_BOTTOMRIGHT) {
+      aChange.x = 0;
+    }
+  }
+
+  if (aVerticalSide == (mVFlip ? NS_SIDE_BOTTOM : NS_SIDE_TOP)) {
+    if (popupAlign == POPUPALIGNMENT_TOPLEFT || popupAlign == POPUPALIGNMENT_TOPRIGHT) {
+      aChange.y = 0;
+    }
+  }
+  else if (aVerticalSide == (mVFlip ? NS_SIDE_TOP : NS_SIDE_BOTTOM)) {
+    if (popupAlign == POPUPALIGNMENT_BOTTOMLEFT || popupAlign == POPUPALIGNMENT_BOTTOMRIGHT) {
+      aChange.y = 0;
+    }
+  }
+}
+
+ConsumeOutsideClicksResult nsMenuPopupFrame::ConsumeOutsideClicks()
+{
+  // If the popup has explicitly set a consume mode, honor that.
+  if (mConsumeRollupEvent != PopupBoxObject::ROLLUP_DEFAULT) {
+    return (mConsumeRollupEvent == PopupBoxObject::ROLLUP_CONSUME) ?
+           ConsumeOutsideClicks_True : ConsumeOutsideClicks_ParentOnly;
+  }
+
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::consumeoutsideclicks,
+                            nsGkAtoms::_true, eCaseMatters)) {
+    return ConsumeOutsideClicks_True;
+  }
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::consumeoutsideclicks,
+                            nsGkAtoms::_false, eCaseMatters)) {
+    return ConsumeOutsideClicks_ParentOnly;
+  }
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::consumeoutsideclicks,
+                            nsGkAtoms::never, eCaseMatters)) {
+    return ConsumeOutsideClicks_Never;
+  }
+
+  nsCOMPtr<nsIContent> parentContent = mContent->GetParent();
+  if (parentContent) {
+    dom::NodeInfo *ni = parentContent->NodeInfo();
+    if (ni->Equals(nsGkAtoms::menulist, kNameSpaceID_XUL)) {
+      return ConsumeOutsideClicks_True;  // Consume outside clicks for combo boxes on all platforms
+    }
+#if defined(XP_WIN)
+    // Don't consume outside clicks for menus in Windows
+    if (ni->Equals(nsGkAtoms::menu, kNameSpaceID_XUL) ||
+        ni->Equals(nsGkAtoms::splitmenu, kNameSpaceID_XUL) ||
+        ni->Equals(nsGkAtoms::popupset, kNameSpaceID_XUL) ||
+        ((ni->Equals(nsGkAtoms::button, kNameSpaceID_XUL) ||
+          ni->Equals(nsGkAtoms::toolbarbutton, kNameSpaceID_XUL)) &&
+         (parentContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                                     nsGkAtoms::menu, eCaseMatters) ||
+          parentContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                                     nsGkAtoms::menuButton, eCaseMatters)))) {
+      return ConsumeOutsideClicks_Never;
+    }
+#endif
+    if (ni->Equals(nsGkAtoms::textbox, kNameSpaceID_XUL)) {
+      // Don't consume outside clicks for autocomplete widget
+      if (parentContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                                     nsGkAtoms::autocomplete, eCaseMatters)) {
+        return ConsumeOutsideClicks_Never;
+      }
+    }
+  }
+
+  return ConsumeOutsideClicks_True;
+}
+
+// XXXroc this is megalame. Fossicking around for a frame of the right
+// type is a recipe for disaster in the long term.
+nsIScrollableFrame* nsMenuPopupFrame::GetScrollFrame(nsIFrame* aStart)
+{
+  if (!aStart)
+    return nullptr;  
+
+  // try start frame and siblings
+  nsIFrame* currFrame = aStart;
+  do {
+    nsIScrollableFrame* sf = do_QueryFrame(currFrame);
+    if (sf)
+      return sf;
+    currFrame = currFrame->GetNextSibling();
+  } while (currFrame);
+
+  // try children
+  currFrame = aStart;
+  do {
+    nsIFrame* childFrame = currFrame->PrincipalChildList().FirstChild();
+    nsIScrollableFrame* sf = GetScrollFrame(childFrame);
+    if (sf)
+      return sf;
+    currFrame = currFrame->GetNextSibling();
+  } while (currFrame);
+
+  return nullptr;
+}
+
+void nsMenuPopupFrame::EnsureMenuItemIsVisible(nsMenuFrame* aMenuItem)
+{
+  if (aMenuItem) {
+    aMenuItem->PresContext()->PresShell()->ScrollFrameRectIntoView(
+      aMenuItem,
+      nsRect(nsPoint(0,0), aMenuItem->GetRect().Size()),
+      nsIPresShell::ScrollAxis(),
+      nsIPresShell::ScrollAxis(),
+      nsIPresShell::SCROLL_OVERFLOW_HIDDEN |
+      nsIPresShell::SCROLL_FIRST_ANCESTOR_ONLY);
+  }
+}
+
+void nsMenuPopupFrame::ChangeByPage(bool aIsUp)
+{
+  // Only scroll by page within menulists.
+  if (!IsMenuList()) {
+    return;
+  }
+
+  nsMenuFrame* newMenu = nullptr;
+  nsIFrame* currentMenu = mCurrentMenu;
+  if (!currentMenu) {
+    // If there is no current menu item, get the first item. When moving up,
+    // just use this as the newMenu and leave currentMenu null so that no
+    // check for a later element is performed. When moving down, set currentMenu
+    // so that we look for one page down from the first item.
+    newMenu = nsXULPopupManager::GetNextMenuItem(this, nullptr, true);
+    if (!aIsUp) {
+      currentMenu = newMenu;
+    }
+  }
+
+  if (currentMenu) {
+    nscoord scrollHeight = mRect.height;
+    nsIScrollableFrame *scrollframe = GetScrollFrame(this);
+    if (scrollframe) {
+      scrollHeight = scrollframe->GetScrollPortRect().height;
+    }
+
+    // Get the position of the current item and add or subtract one popup's
+    // height to or from it.
+    nscoord targetPosition = aIsUp ? currentMenu->GetRect().YMost() - scrollHeight :
+                                     currentMenu->GetRect().y + scrollHeight;
+
+    // Indicates that the last visible child was a valid menuitem.
+    bool lastWasValid = false;
+
+    // Look for the next child which is just past the target position. This child
+    // will need to be selected.
+    while (currentMenu) {
+      // Only consider menu frames.
+      nsMenuFrame* menuFrame = do_QueryFrame(currentMenu);
+      if (menuFrame &&
+          nsXULPopupManager::IsValidMenuItem(menuFrame->GetContent(), true)) {
+
+        // If the right position was found, break out. Otherwise, look for another item.
+        if ((!aIsUp && currentMenu->GetRect().YMost() > targetPosition) ||
+            (aIsUp && currentMenu->GetRect().y < targetPosition)) {
+
+          // If the last visible child was not a valid menuitem or was disabled,
+          // use this as the menu to select, skipping over any non-valid items at
+          // the edge of the page.
+          if (!lastWasValid) {
+            newMenu = menuFrame;
+          }
+
+          break;
+        }
+
+        // Assign this item to newMenu. This item will be selected in case we
+        // don't find any more. 
+        lastWasValid = true;
+        newMenu = menuFrame;
+      }
+      else {
+        lastWasValid = false;
+      }
+
+      currentMenu = aIsUp ? currentMenu->GetPrevSibling() :
+                            currentMenu->GetNextSibling();
+    }
+  }
+
+  // Select the new menuitem.
+  if (newMenu) {
+    ChangeMenuItem(newMenu, false, true);
+  }
+}
+
+NS_IMETHODIMP nsMenuPopupFrame::SetCurrentMenuItem(nsMenuFrame* aMenuItem)
+{
+  if (mCurrentMenu == aMenuItem)
+    return NS_OK;
+
+  if (mCurrentMenu) {
+    mCurrentMenu->SelectMenu(false);
+  }
+
+  if (aMenuItem) {
+    EnsureMenuItemIsVisible(aMenuItem);
+    aMenuItem->SelectMenu(true);
+  }
+
+  mCurrentMenu = aMenuItem;
+
+  return NS_OK;
+}
+
+void
+nsMenuPopupFrame::CurrentMenuIsBeingDestroyed()
+{
+  mCurrentMenu = nullptr;
+}
+
+NS_IMETHODIMP
+nsMenuPopupFrame::ChangeMenuItem(nsMenuFrame* aMenuItem,
+                                 bool aSelectFirstItem,
+                                 bool aFromKey)
+{
+  if (mCurrentMenu == aMenuItem)
+    return NS_OK;
+
+  // When a context menu is open, the current menu is locked, and no change
+  // to the menu is allowed.
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (!mIsContextMenu && pm && pm->HasContextMenu(this))
+    return NS_OK;
+
+  // Unset the current child.
+  if (mCurrentMenu) {
+    mCurrentMenu->SelectMenu(false);
+    nsMenuPopupFrame* popup = mCurrentMenu->GetPopup();
+    if (popup) {
+      if (mCurrentMenu->IsOpen()) {
+        if (pm)
+          pm->HidePopupAfterDelay(popup);
+      }
+    }
+  }
+
+  // Set the new child.
+  if (aMenuItem) {
+    EnsureMenuItemIsVisible(aMenuItem);
+    aMenuItem->SelectMenu(true);
+
+    // On Windows, a menulist should update its value whenever navigation was
+    // done by the keyboard.
+#ifdef XP_WIN
+    if (aFromKey && IsOpen() && IsMenuList()) {
+      // Fire a command event as the new item, but we don't want to close
+      // the menu, blink it, or update any other state of the menuitem. The
+      // command event will cause the item to be selected.
+      nsContentUtils::DispatchXULCommand(aMenuItem->GetContent(), /* aTrusted = */ true,
+                                         nullptr, PresContext()->PresShell(),
+                                         false, false, false, false);
+    }
+#endif
+  }
+
+  mCurrentMenu = aMenuItem;
+
+  return NS_OK;
+}
+
+nsMenuFrame*
+nsMenuPopupFrame::Enter(WidgetGUIEvent* aEvent)
+{
+  mIncrementalString.Truncate();
+
+  // Give it to the child.
+  if (mCurrentMenu)
+    return mCurrentMenu->Enter(aEvent);
+
+  return nullptr;
+}
+
+nsMenuFrame*
+nsMenuPopupFrame::FindMenuWithShortcut(nsIDOMKeyEvent* aKeyEvent, bool& doAction)
+{
+  uint32_t charCode, keyCode;
+  aKeyEvent->GetCharCode(&charCode);
+  aKeyEvent->GetKeyCode(&keyCode);
+
+  doAction = false;
+
+  // Enumerate over our list of frames.
+  auto insertion = PresContext()->PresShell()->
+    FrameConstructor()->GetInsertionPoint(GetContent(), nullptr);
+  nsContainerFrame* immediateParent = insertion.mParentFrame;
+  if (!immediateParent)
+    immediateParent = this;
+
+  uint32_t matchCount = 0, matchShortcutCount = 0;
+  bool foundActive = false;
+  bool isShortcut;
+  nsMenuFrame* frameBefore = nullptr;
+  nsMenuFrame* frameAfter = nullptr;
+  nsMenuFrame* frameShortcut = nullptr;
+
+  nsIContent* parentContent = mContent->GetParent();
+
+  bool isMenu = parentContent &&
+                  !parentContent->NodeInfo()->Equals(nsGkAtoms::menulist, kNameSpaceID_XUL);
+
+  DOMTimeStamp keyTime;
+  aKeyEvent->AsEvent()->GetTimeStamp(&keyTime);
+
+  if (charCode == 0) {
+    if (keyCode == nsIDOMKeyEvent::DOM_VK_BACK_SPACE) {
+      if (!isMenu && !mIncrementalString.IsEmpty()) {
+        mIncrementalString.SetLength(mIncrementalString.Length() - 1);
+        return nullptr;
+      }
+      else {
+#ifdef XP_WIN
+        nsCOMPtr<nsISound> soundInterface = do_CreateInstance("@mozilla.org/sound;1");
+        if (soundInterface)
+          soundInterface->Beep();
+#endif  // #ifdef XP_WIN
+      }
+    }
+    return nullptr;
+  }
+  else {
+    char16_t uniChar = ToLowerCase(static_cast<char16_t>(charCode));
+    if (isMenu) {
+      // Menu supports only first-letter navigation
+      mIncrementalString = uniChar;
+    } else if (IsWithinIncrementalTime(keyTime)) {
+      mIncrementalString.Append(uniChar);
+    } else {
+      // Interval too long, treat as new typing
+      mIncrementalString = uniChar;
+    }
+  }
+
+  // See bug 188199 & 192346, if all letters in incremental string are same, just try to match the first one
+  nsAutoString incrementalString(mIncrementalString);
+  uint32_t charIndex = 1, stringLength = incrementalString.Length();
+  while (charIndex < stringLength && incrementalString[charIndex] == incrementalString[charIndex - 1]) {
+    charIndex++;
+  }
+  if (charIndex == stringLength) {
+    incrementalString.Truncate(1);
+    stringLength = 1;
+  }
+
+  sLastKeyTime = keyTime;
+
+  // NOTE: If you crashed here due to a bogus |immediateParent| it is 
+  //       possible that the menu whose shortcut is being looked up has 
+  //       been destroyed already.  One strategy would be to 
+  //       setTimeout(<func>,0) as detailed in:
+  //       <http://bugzilla.mozilla.org/show_bug.cgi?id=126675#c32>
+  nsIFrame* firstMenuItem = nsXULPopupManager::GetNextMenuItem(immediateParent, nullptr, true);
+  nsIFrame* currFrame = firstMenuItem;
+
+  int32_t menuAccessKey = -1;
+  nsMenuBarListener::GetMenuAccessKey(&menuAccessKey);
+
+  // We start searching from first child. This process is divided into two parts
+  //   -- before current and after current -- by the current item
+  while (currFrame) {
+    nsIContent* current = currFrame->GetContent();
+    nsAutoString textKey;
+    if (menuAccessKey >= 0) {
+      // Get the shortcut attribute.
+      current->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, textKey);
+    }
+    if (textKey.IsEmpty()) { // No shortcut, try first letter
+      isShortcut = false;
+      current->GetAttr(kNameSpaceID_None, nsGkAtoms::label, textKey);
+      if (textKey.IsEmpty()) // No label, try another attribute (value)
+        current->GetAttr(kNameSpaceID_None, nsGkAtoms::value, textKey);
+    }
+    else
+      isShortcut = true;
+
+    if (StringBeginsWith(textKey, incrementalString,
+                         nsCaseInsensitiveStringComparator())) {
+      // mIncrementalString is a prefix of textKey
+      nsMenuFrame* menu = do_QueryFrame(currFrame);
+      if (menu) {
+        // There is one match
+        matchCount++;
+        if (isShortcut) {
+          // There is one shortcut-key match
+          matchShortcutCount++;
+          // Record the matched item. If there is only one matched shortcut item, do it
+          frameShortcut = menu;
+        }
+        if (!foundActive) {
+          // It's a first candidate item located before/on the current item
+          if (!frameBefore)
+            frameBefore = menu;
+        }
+        else {
+          // It's a first candidate item located after the current item
+          if (!frameAfter)
+            frameAfter = menu;
+        }
+      }
+      else
+        return nullptr;
+    }
+
+    // Get the active status
+    if (current->AttrValueIs(kNameSpaceID_None, nsGkAtoms::menuactive,
+                             nsGkAtoms::_true, eCaseMatters)) {
+      foundActive = true;
+      if (stringLength > 1) {
+        // If there is more than one char typed, the current item has highest priority,
+        //   otherwise the item next to current has highest priority
+        if (currFrame == frameBefore)
+          return frameBefore;
+      }
+    }
+
+    nsMenuFrame* menu = do_QueryFrame(currFrame);
+    currFrame = nsXULPopupManager::GetNextMenuItem(immediateParent, menu, true);
+    if (currFrame == firstMenuItem)
+      break;
+  }
+
+  doAction = (isMenu && (matchCount == 1 || matchShortcutCount == 1));
+
+  if (matchShortcutCount == 1) // We have one matched shortcut item
+    return frameShortcut;
+  if (frameAfter) // If we have matched item after the current, use it
+    return frameAfter;
+  else if (frameBefore) // If we haven't, use the item before the current
+    return frameBefore;
+
+  // If we don't match anything, rollback the last typing
+  mIncrementalString.SetLength(mIncrementalString.Length() - 1);
+
+  // didn't find a matching menu item
+#ifdef XP_WIN
+  // behavior on Windows - this item is in a menu popup off of the
+  // menu bar, so beep and do nothing else
+  if (isMenu) {
+    nsCOMPtr<nsISound> soundInterface = do_CreateInstance("@mozilla.org/sound;1");
+    if (soundInterface)
+      soundInterface->Beep();
+  }
+#endif  // #ifdef XP_WIN
+
+  return nullptr;
+}
+
+void
+nsMenuPopupFrame::LockMenuUntilClosed(bool aLock)
+{
+  mIsMenuLocked = aLock;
+
+  // Lock / unlock the parent, too.
+  nsMenuFrame* menu = do_QueryFrame(GetParent());
+  if (menu) {
+    nsMenuParent* parentParent = menu->GetMenuParent();
+    if (parentParent) {
+      parentParent->LockMenuUntilClosed(aLock);
+    }
+  }
+}
+
+nsIWidget*
+nsMenuPopupFrame::GetWidget()
+{
+  nsView * view = GetRootViewForPopup(this);
+  if (!view)
+    return nullptr;
+
+  return view->GetWidget();
+}
+
+void
+nsMenuPopupFrame::AttachedDismissalListener()
+{
+  mConsumeRollupEvent = PopupBoxObject::ROLLUP_DEFAULT;
+}
+
+// helpers /////////////////////////////////////////////////////////////
+
+nsresult 
+nsMenuPopupFrame::AttributeChanged(int32_t aNameSpaceID,
+                                   nsIAtom* aAttribute,
+                                   int32_t aModType)
+
+{
+  nsresult rv = nsBoxFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                             aModType);
+  
+  if (aAttribute == nsGkAtoms::left || aAttribute == nsGkAtoms::top)
+    MoveToAttributePosition();
+
+#ifndef MOZ_GTK2
+  if (aAttribute == nsGkAtoms::noautohide) {
+    nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+    if (pm)
+      pm->EnableRollup(mContent, !IsNoAutoHide());
+  }
+#endif
+
+  if (aAttribute == nsGkAtoms::label) {
+    // set the label for the titlebar
+    nsView* view = GetView();
+    if (view) {
+      nsIWidget* widget = view->GetWidget();
+      if (widget) {
+        nsAutoString title;
+        mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::label, title);
+        if (!title.IsEmpty()) {
+          widget->SetTitle(title);
+        }
+      }
+    }
+  }
+
+  return rv;
+}
+
+void
+nsMenuPopupFrame::MoveToAttributePosition()
+{
+  // Move the widget around when the user sets the |left| and |top| attributes. 
+  // Note that this is not the best way to move the widget, as it results in lots
+  // of FE notifications and is likely to be slow as molasses. Use |moveTo| on
+  // PopupBoxObject if possible.
+  nsAutoString left, top;
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::left, left);
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::top, top);
+  nsresult err1, err2;
+  mozilla::CSSIntPoint pos(left.ToInteger(&err1), top.ToInteger(&err2));
+
+  if (NS_SUCCEEDED(err1) && NS_SUCCEEDED(err2))
+    MoveTo(pos, false);
+}
+
+void
+nsMenuPopupFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  if (mReflowCallbackData.mPosted) {
+    PresContext()->PresShell()->CancelReflowCallback(this);
+    mReflowCallbackData.Clear();
+  }
+
+  nsMenuFrame* menu = do_QueryFrame(GetParent());
+  if (menu) {
+    // clear the open attribute on the parent menu
+    nsContentUtils::AddScriptRunner(
+      new nsUnsetAttrRunnable(menu->GetContent(), nsGkAtoms::open));
+  }
+
+  ClearPopupShownDispatcher();
+
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm)
+    pm->PopupDestroyed(this);
+
+  nsIRootBox* rootBox =
+    nsIRootBox::GetRootBox(PresContext()->GetPresShell());
+  if (rootBox && rootBox->GetDefaultTooltip() == mContent) {
+    rootBox->SetDefaultTooltip(nullptr);
+  }
+
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+
+void
+nsMenuPopupFrame::MoveTo(const CSSIntPoint& aPos, bool aUpdateAttrs)
+{
+  nsIWidget* widget = GetWidget();
+  if ((mScreenRect.x == aPos.x && mScreenRect.y == aPos.y) &&
+      (!widget || widget->GetClientOffset() == mLastClientOffset)) {
+    return;
+  }
+
+  // reposition the popup at the specified coordinates. Don't clear the anchor
+  // and position, because the popup can be reset to its anchor position by
+  // using (-1, -1) as coordinates. Subtract off the margin as it will be
+  // added to the position when SetPopupPosition is called.
+  nsMargin margin(0, 0, 0, 0);
+  StyleMargin()->GetMargin(margin);
+
+  // Workaround for bug 788189.  See also bug 708278 comment #25 and following.
+  if (mAdjustOffsetForContextMenu) {
+    margin.left += nsPresContext::CSSPixelsToAppUnits(LookAndFeel::GetInt(
+                     LookAndFeel::eIntID_ContextMenuOffsetHorizontal));
+    margin.top += nsPresContext::CSSPixelsToAppUnits(LookAndFeel::GetInt(
+                     LookAndFeel::eIntID_ContextMenuOffsetVertical));
+  }
+
+  nsPresContext* presContext = PresContext();
+  mAnchorType = MenuPopupAnchorType_Point;
+  mScreenRect.x = aPos.x - presContext->AppUnitsToIntCSSPixels(margin.left);
+  mScreenRect.y = aPos.y - presContext->AppUnitsToIntCSSPixels(margin.top);
+
+  SetPopupPosition(nullptr, true, false, true);
+
+  nsCOMPtr<nsIContent> popup = mContent;
+  if (aUpdateAttrs && (popup->HasAttr(kNameSpaceID_None, nsGkAtoms::left) ||
+                       popup->HasAttr(kNameSpaceID_None, nsGkAtoms::top)))
+  {
+    nsAutoString left, top;
+    left.AppendInt(aPos.x);
+    top.AppendInt(aPos.y);
+    popup->SetAttr(kNameSpaceID_None, nsGkAtoms::left, left, false);
+    popup->SetAttr(kNameSpaceID_None, nsGkAtoms::top, top, false);
+  }
+}
+
+void
+nsMenuPopupFrame::MoveToAnchor(nsIContent* aAnchorContent,
+                               const nsAString& aPosition,
+                               int32_t aXPos, int32_t aYPos,
+                               bool aAttributesOverride)
+{
+  NS_ASSERTION(IsVisible(), "popup must be visible to move it");
+
+  nsPopupState oldstate = mPopupState;
+  InitializePopup(aAnchorContent, mTriggerContent, aPosition,
+                  aXPos, aYPos, MenuPopupAnchorType_Node, aAttributesOverride);
+  // InitializePopup changed the state so reset it.
+  mPopupState = oldstate;
+
+  // Pass false here so that flipping and adjusting to fit on the screen happen.
+  SetPopupPosition(nullptr, false, false, true);
+}
+
+bool
+nsMenuPopupFrame::GetAutoPosition()
+{
+  return mShouldAutoPosition;
+}
+
+void
+nsMenuPopupFrame::SetAutoPosition(bool aShouldAutoPosition)
+{
+  mShouldAutoPosition = aShouldAutoPosition;
+}
+
+void
+nsMenuPopupFrame::SetConsumeRollupEvent(uint32_t aConsumeMode)
+{
+  mConsumeRollupEvent = aConsumeMode;
+}
+
+int8_t
+nsMenuPopupFrame::GetAlignmentPosition() const
+{
+  // The code below handles most cases of alignment, anchor and position values. Those that are
+  // not handled just return POPUPPOSITION_UNKNOWN.
+
+  if (mPosition == POPUPPOSITION_OVERLAP || mPosition == POPUPPOSITION_AFTERPOINTER ||
+      mPosition == POPUPPOSITION_SELECTION)
+    return mPosition;
+
+  int8_t position = mPosition;
+
+  if (position == POPUPPOSITION_UNKNOWN) {
+    switch (mPopupAnchor) {
+      case POPUPALIGNMENT_BOTTOMCENTER:
+        position = mPopupAlignment == POPUPALIGNMENT_TOPRIGHT ?
+                     POPUPPOSITION_AFTEREND : POPUPPOSITION_AFTERSTART;
+        break;
+      case POPUPALIGNMENT_TOPCENTER:
+        position = mPopupAlignment == POPUPALIGNMENT_BOTTOMRIGHT ?
+                     POPUPPOSITION_BEFOREEND : POPUPPOSITION_BEFORESTART;
+        break;
+      case POPUPALIGNMENT_LEFTCENTER:
+        position = mPopupAlignment == POPUPALIGNMENT_BOTTOMRIGHT ?
+                     POPUPPOSITION_STARTAFTER : POPUPPOSITION_STARTBEFORE;
+        break;
+      case POPUPALIGNMENT_RIGHTCENTER:
+        position = mPopupAlignment == POPUPALIGNMENT_BOTTOMLEFT ?
+                     POPUPPOSITION_ENDAFTER : POPUPPOSITION_ENDBEFORE;
+        break;
+      default:
+        break;
+    }
+  }
+
+  if (mHFlip) {
+    position = POPUPPOSITION_HFLIP(position);
+  }
+
+  if (mVFlip) {
+    position = POPUPPOSITION_VFLIP(position);
+  }
+
+  return position;
+}
+
+/**
+ * KEEP THIS IN SYNC WITH nsContainerFrame::CreateViewForFrame
+ * as much as possible. Until we get rid of views finally...
+ */
+void
+nsMenuPopupFrame::CreatePopupView()
+{
+  if (HasView()) {
+    return;
+  }
+
+  nsViewManager* viewManager = PresContext()->GetPresShell()->GetViewManager();
+  NS_ASSERTION(nullptr != viewManager, "null view manager");
+
+  // Create a view
+  nsView* parentView = viewManager->GetRootView();
+  nsViewVisibility visibility = nsViewVisibility_kHide;
+  int32_t zIndex = INT32_MAX;
+  bool    autoZIndex = false;
+
+  NS_ASSERTION(parentView, "no parent view");
+
+  // Create a view
+  nsView *view = viewManager->CreateView(GetRect(), parentView, visibility);
+  viewManager->SetViewZIndex(view, autoZIndex, zIndex);
+  // XXX put view last in document order until we can do better
+  viewManager->InsertChild(parentView, view, nullptr, true);
+
+  // Remember our view
+  SetView(view);
+
+  NS_FRAME_LOG(NS_FRAME_TRACE_CALLS,
+    ("nsMenuPopupFrame::CreatePopupView: frame=%p view=%p", this, view));
+}
diff --git a/layout/xul/nsMenuPopupFrame.h b/layout/xul/nsMenuPopupFrame.h
new file mode 100644
index 0000000000..b32073960c
--- /dev/null
+++ b/layout/xul/nsMenuPopupFrame.h
@@ -0,0 +1,628 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// nsMenuPopupFrame
+//
+
+#ifndef nsMenuPopupFrame_h__
+#define nsMenuPopupFrame_h__
+
+#include "mozilla/Attributes.h"
+#include "nsIAtom.h"
+#include "nsGkAtoms.h"
+#include "nsCOMPtr.h"
+#include "nsMenuFrame.h"
+
+#include "nsBoxFrame.h"
+#include "nsMenuParent.h"
+
+#include "nsITimer.h"
+
+#include "Units.h"
+
+class nsIWidget;
+
+// XUL popups can be in several different states. When opening a popup, the
+// state changes as follows:
+//   ePopupClosed - initial state
+//   ePopupShowing - during the period when the popupshowing event fires
+//   ePopupOpening - between the popupshowing event and being visible. Creation
+//                   of the child frames, layout and reflow occurs in this
+//                   state. The popup is stored in the popup manager's list of
+//                   open popups during this state.
+//   ePopupVisible - layout is done and the popup's view and widget are made
+//                   visible. The popup is visible on screen but may be
+//                   transitioning. The popupshown event has not yet fired.
+//   ePopupShown - the popup has been shown and is fully ready. This state is
+//                 assigned just before the popupshown event fires.
+// When closing a popup:
+//   ePopupHidden - during the period when the popuphiding event fires and
+//                  the popup is removed.
+//   ePopupClosed - the popup's widget is made invisible.
+enum nsPopupState {
+  // state when a popup is not open
+  ePopupClosed,
+  // state from when a popup is requested to be shown to after the
+  // popupshowing event has been fired.
+  ePopupShowing,
+  // state while a popup is waiting to be laid out and positioned
+  ePopupPositioning,
+  // state while a popup is open but the widget is not yet visible
+  ePopupOpening,
+  // state while a popup is visible and waiting for the popupshown event
+  ePopupVisible,
+  // state while a popup is open and visible on screen
+  ePopupShown,
+  // state from when a popup is requested to be hidden to when it is closed.
+  ePopupHiding,
+  // state which indicates that the popup was hidden without firing the
+  // popuphiding or popuphidden events. It is used when executing a menu
+  // command because the menu needs to be hidden before the command event
+  // fires, yet the popuphiding and popuphidden events are fired after. This
+  // state can also occur when the popup is removed because the document is
+  // unloaded.
+  ePopupInvisible
+};
+
+enum ConsumeOutsideClicksResult {
+  ConsumeOutsideClicks_ParentOnly = 0, // Only consume clicks on the parent anchor
+  ConsumeOutsideClicks_True = 1, // Always consume clicks
+  ConsumeOutsideClicks_Never = 2 // Never consume clicks
+};
+
+// How a popup may be flipped. Flipping to the outside edge is like how
+// a submenu would work. The entire popup is flipped to the opposite side
+// of the anchor.
+enum FlipStyle {
+  FlipStyle_None = 0,
+  FlipStyle_Outside = 1,
+  FlipStyle_Inside = 2
+};
+
+// Values for the flip attribute
+enum FlipType {
+  FlipType_Default = 0,
+  FlipType_None = 1,    // don't try to flip or translate to stay onscreen
+  FlipType_Both = 2,    // flip in both directions
+  FlipType_Slide = 3    // allow the arrow to "slide" instead of resizing
+};
+
+enum MenuPopupAnchorType {
+  MenuPopupAnchorType_Node = 0, // anchored to a node
+  MenuPopupAnchorType_Point = 1, // unanchored and positioned at a screen point
+  MenuPopupAnchorType_Rect = 2, // anchored at a screen rectangle
+};
+
+// values are selected so that the direction can be flipped just by
+// changing the sign
+#define POPUPALIGNMENT_NONE 0
+#define POPUPALIGNMENT_TOPLEFT 1
+#define POPUPALIGNMENT_TOPRIGHT -1
+#define POPUPALIGNMENT_BOTTOMLEFT 2
+#define POPUPALIGNMENT_BOTTOMRIGHT -2
+
+#define POPUPALIGNMENT_LEFTCENTER 16
+#define POPUPALIGNMENT_RIGHTCENTER -16
+#define POPUPALIGNMENT_TOPCENTER 17
+#define POPUPALIGNMENT_BOTTOMCENTER 18
+
+// The constants here are selected so that horizontally and vertically flipping
+// can be easily handled using the two flip macros below.
+#define POPUPPOSITION_UNKNOWN -1
+#define POPUPPOSITION_BEFORESTART 0
+#define POPUPPOSITION_BEFOREEND 1
+#define POPUPPOSITION_AFTERSTART 2
+#define POPUPPOSITION_AFTEREND 3
+#define POPUPPOSITION_STARTBEFORE 4
+#define POPUPPOSITION_ENDBEFORE 5
+#define POPUPPOSITION_STARTAFTER 6
+#define POPUPPOSITION_ENDAFTER 7
+#define POPUPPOSITION_OVERLAP 8
+#define POPUPPOSITION_AFTERPOINTER 9
+#define POPUPPOSITION_SELECTION 10
+
+#define POPUPPOSITION_HFLIP(v) (v ^ 1)
+#define POPUPPOSITION_VFLIP(v) (v ^ 2)
+
+nsIFrame* NS_NewMenuPopupFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+class nsView;
+class nsMenuPopupFrame;
+
+// this class is used for dispatching popupshown events asynchronously.
+class nsXULPopupShownEvent : public mozilla::Runnable,
+                             public nsIDOMEventListener
+{
+public:
+  nsXULPopupShownEvent(nsIContent *aPopup, nsPresContext* aPresContext)
+    : mPopup(aPopup), mPresContext(aPresContext)
+  {
+  }
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIRUNNABLE
+  NS_DECL_NSIDOMEVENTLISTENER
+
+  void CancelListener();
+
+protected:
+  virtual ~nsXULPopupShownEvent() { }
+
+private:
+  nsCOMPtr<nsIContent> mPopup;
+  RefPtr<nsPresContext> mPresContext;
+};
+
+class nsMenuPopupFrame final : public nsBoxFrame, public nsMenuParent,
+                               public nsIReflowCallback
+{
+public:
+  NS_DECL_QUERYFRAME_TARGET(nsMenuPopupFrame)
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  explicit nsMenuPopupFrame(nsStyleContext* aContext);
+
+  // nsMenuParent interface
+  virtual nsMenuFrame* GetCurrentMenuItem() override;
+  NS_IMETHOD SetCurrentMenuItem(nsMenuFrame* aMenuItem) override;
+  virtual void CurrentMenuIsBeingDestroyed() override;
+  NS_IMETHOD ChangeMenuItem(nsMenuFrame* aMenuItem,
+                            bool aSelectFirstItem,
+                            bool aFromKey) override;
+
+  // as popups are opened asynchronously, the popup pending state is used to
+  // prevent multiple requests from attempting to open the same popup twice
+  nsPopupState PopupState() { return mPopupState; }
+  void SetPopupState(nsPopupState aPopupState) { mPopupState = aPopupState; }
+
+  NS_IMETHOD SetActive(bool aActiveFlag) override { return NS_OK; } // We don't care.
+  virtual bool IsActive() override { return false; }
+  virtual bool IsMenuBar() override { return false; }
+
+  /*
+   * When this popup is open, should clicks outside of it be consumed?
+   * Return true if the popup should rollup on an outside click, 
+   * but consume that click so it can't be used for anything else.
+   * Return false to allow clicks outside the popup to activate content 
+   * even when the popup is open.
+   * ---------------------------------------------------------------------
+   * 
+   * Should clicks outside of a popup be eaten?
+   *
+   *       Menus     Autocomplete     Comboboxes
+   * Mac     Eat           No              Eat
+   * Win     No            No              Eat     
+   * Unix    Eat           No              Eat
+   *
+   */
+  ConsumeOutsideClicksResult ConsumeOutsideClicks();
+
+  virtual bool IsContextMenu() override { return mIsContextMenu; }
+
+  virtual bool MenuClosed() override { return true; }
+
+  virtual void LockMenuUntilClosed(bool aLock) override;
+  virtual bool IsMenuLocked() override { return mIsMenuLocked; }
+
+  nsIWidget* GetWidget();
+
+  // The dismissal listener gets created and attached to the window.
+  void AttachedDismissalListener();
+
+  // Overridden methods
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  // returns true if the popup is a panel with the noautohide attribute set to
+  // true. These panels do not roll up automatically.
+  bool IsNoAutoHide() const;
+
+  nsPopupLevel PopupLevel() const
+  {
+    return PopupLevel(IsNoAutoHide()); 
+  }
+
+  void EnsureWidget();
+
+  nsresult CreateWidgetForView(nsView* aView);
+  uint8_t GetShadowStyle();
+
+  virtual void SetInitialChildList(ChildListID  aListID,
+                                   nsFrameList& aChildList) override;
+
+  virtual bool IsLeaf() const override;
+
+  // layout, position and display the popup as needed
+  void LayoutPopup(nsBoxLayoutState& aState, nsIFrame* aParentMenu,
+                   nsIFrame* aAnchor, bool aSizedToPopup);
+
+  nsView* GetRootViewForPopup(nsIFrame* aStartFrame);
+
+  // Set the position of the popup either relative to the anchor aAnchorFrame
+  // (or the frame for mAnchorContent if aAnchorFrame is null), anchored at a
+  // rectangle, or at a specific point if a screen position is set. The popup
+  // will be adjusted so that it is on screen. If aIsMove is true, then the
+  // popup is being moved, and should not be flipped. If aNotify is true, then
+  // a popuppositioned event is sent.
+  nsresult SetPopupPosition(nsIFrame* aAnchorFrame, bool aIsMove,
+                            bool aSizedToPopup, bool aNotify);
+
+  bool HasGeneratedChildren() { return mGeneratedChildren; }
+  void SetGeneratedChildren() { mGeneratedChildren = true; }
+
+  // called when the Enter key is pressed while the popup is open. This will
+  // just pass the call down to the current menu, if any. If a current menu
+  // should be opened as a result, this method should return the frame for
+  // that menu, or null if no menu should be opened. Also, calling Enter will
+  // reset the current incremental search string, calculated in
+  // FindMenuWithShortcut.
+  nsMenuFrame* Enter(mozilla::WidgetGUIEvent* aEvent);
+
+  nsPopupType PopupType() const { return mPopupType; }
+  bool IsMenu() override { return mPopupType == ePopupTypeMenu; }
+  bool IsOpen() override { return mPopupState == ePopupOpening ||
+                                      mPopupState == ePopupVisible ||
+                                      mPopupState == ePopupShown; }
+  bool IsVisible() { return mPopupState == ePopupVisible ||
+                            mPopupState == ePopupShown; }
+
+  // Return true if the popup is for a menulist.
+  bool IsMenuList();
+
+  bool IsMouseTransparent() { return mMouseTransparent; }
+
+  static nsIContent* GetTriggerContent(nsMenuPopupFrame* aMenuPopupFrame);
+  void ClearTriggerContent() { mTriggerContent = nullptr; }
+
+  // returns true if the popup is in a content shell, or false for a popup in
+  // a chrome shell
+  bool IsInContentShell() { return mInContentShell; }
+
+  // the Initialize methods are used to set the anchor position for
+  // each way of opening a popup.
+  void InitializePopup(nsIContent* aAnchorContent,
+                       nsIContent* aTriggerContent,
+                       const nsAString& aPosition,
+                       int32_t aXPos, int32_t aYPos,
+                       MenuPopupAnchorType aAnchorType,
+                       bool aAttributesOverride);
+
+  void InitializePopupAtRect(nsIContent* aTriggerContent,
+                             const nsAString& aPosition,
+                             const nsIntRect& aRect,
+                             bool aAttributesOverride);
+
+  /**
+   * @param aIsContextMenu if true, then the popup is
+   * positioned at a slight offset from aXPos/aYPos to ensure the
+   * (presumed) mouse position is not over the menu.
+   */
+  void InitializePopupAtScreen(nsIContent* aTriggerContent,
+                               int32_t aXPos, int32_t aYPos,
+                               bool aIsContextMenu);
+
+  void InitializePopupWithAnchorAlign(nsIContent* aAnchorContent,
+                                      nsAString& aAnchor,
+                                      nsAString& aAlign,
+                                      int32_t aXPos, int32_t aYPos);
+
+  // indicate that the popup should be opened
+  void ShowPopup(bool aIsContextMenu);
+  // indicate that the popup should be hidden. The new state should either be
+  // ePopupClosed or ePopupInvisible.
+  void HidePopup(bool aDeselectMenu, nsPopupState aNewState);
+
+  // locate and return the menu frame that should be activated for the
+  // supplied key event. If doAction is set to true by this method,
+  // then the menu's action should be carried out, as if the user had pressed
+  // the Enter key. If doAction is false, the menu should just be highlighted.
+  // This method also handles incremental searching in menus so the user can
+  // type the first few letters of an item/s name to select it.
+  nsMenuFrame* FindMenuWithShortcut(nsIDOMKeyEvent* aKeyEvent, bool& doAction);
+
+  void ClearIncrementalString() { mIncrementalString.Truncate(); }
+  static bool IsWithinIncrementalTime(DOMTimeStamp time) {
+    return !sTimeoutOfIncrementalSearch || time - sLastKeyTime <= sTimeoutOfIncrementalSearch;
+  }
+
+  virtual nsIAtom* GetType() const override { return nsGkAtoms::menuPopupFrame; }
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override
+  {
+      return MakeFrameName(NS_LITERAL_STRING("MenuPopup"), aResult);
+  }
+#endif
+
+  void EnsureMenuItemIsVisible(nsMenuFrame* aMenuFrame);
+
+  void ChangeByPage(bool aIsUp);
+
+  // Move the popup to the screen coordinate |aPos| in CSS pixels.
+  // If aUpdateAttrs is true, and the popup already has left or top attributes,
+  // then those attributes are updated to the new location.
+  // The frame may be destroyed by this method.
+  void MoveTo(const mozilla::CSSIntPoint& aPos, bool aUpdateAttrs);
+
+  void MoveToAnchor(nsIContent* aAnchorContent,
+                    const nsAString& aPosition,
+                    int32_t aXPos, int32_t aYPos,
+                    bool aAttributesOverride);
+
+  bool GetAutoPosition();
+  void SetAutoPosition(bool aShouldAutoPosition);
+  void SetConsumeRollupEvent(uint32_t aConsumeMode);
+
+  nsIScrollableFrame* GetScrollFrame(nsIFrame* aStart);
+
+  void SetOverrideConstraintRect(mozilla::LayoutDeviceIntRect aRect) {
+    mOverrideConstraintRect = ToAppUnits(aRect, PresContext()->AppUnitsPerCSSPixel());
+  }
+
+  // For a popup that should appear anchored at the given rect, determine
+  // the screen area that it is constrained by. This will be the available
+  // area of the screen the popup should be displayed on. Content popups,
+  // however, will also be constrained by the content area, given by
+  // aRootScreenRect. All coordinates are in app units.
+  // For non-toplevel popups (which will always be panels), we will also
+  // constrain them to the available screen rect, ie they will not fall
+  // underneath the taskbar, dock or other fixed OS elements.
+  // This operates in device pixels.
+  mozilla::LayoutDeviceIntRect
+  GetConstraintRect(const mozilla::LayoutDeviceIntRect& aAnchorRect,
+                    const mozilla::LayoutDeviceIntRect& aRootScreenRect,
+                    nsPopupLevel aPopupLevel);
+
+  // Determines whether the given edges of the popup may be moved, where
+  // aHorizontalSide and aVerticalSide are one of the NS_SIDE_* constants, or
+  // 0 for no movement in that direction. aChange is the distance to move on
+  // those sides. If will be reset to 0 if the side cannot be adjusted at all
+  // in that direction. For example, a popup cannot be moved if it is anchored
+  // on a particular side.
+  //
+  // Later, when bug 357725 is implemented, we can make this adjust aChange by
+  // the amount that the side can be resized, so that minimums and maximums
+  // can be taken into account.
+  void CanAdjustEdges(int8_t aHorizontalSide,
+                      int8_t aVerticalSide,
+                      mozilla::LayoutDeviceIntPoint& aChange);
+
+  // Return true if the popup is positioned relative to an anchor.
+  bool IsAnchored() const { return mAnchorType != MenuPopupAnchorType_Point; }
+
+  // Return the anchor if there is one.
+  nsIContent* GetAnchor() const { return mAnchorContent; }
+
+  // Return the screen coordinates in CSS pixels of the popup,
+  // or (-1, -1, 0, 0) if anchored.
+  nsIntRect GetScreenAnchorRect() const { return mScreenRect; }
+
+  mozilla::LayoutDeviceIntPoint GetLastClientOffset() const
+  {
+    return mLastClientOffset;
+  }
+
+  // Return the alignment of the popup
+  int8_t GetAlignmentPosition() const;
+
+  // Return the offset applied to the alignment of the popup
+  nscoord GetAlignmentOffset() const { return mAlignmentOffset; }
+
+  // Clear the mPopupShownDispatcher, remove the listener and return true if
+  // mPopupShownDispatcher was non-null.
+  bool ClearPopupShownDispatcher()
+  {
+    if (mPopupShownDispatcher) {
+      mPopupShownDispatcher->CancelListener();
+      mPopupShownDispatcher = nullptr;
+      return true;
+    }
+
+    return false;
+  }
+
+  void ShowWithPositionedEvent() {
+    mPopupState = ePopupPositioning;
+    mShouldAutoPosition = true;
+  }
+
+  // nsIReflowCallback
+  virtual bool ReflowFinished() override;
+  virtual void ReflowCallbackCanceled() override;
+
+protected:
+
+  // returns the popup's level.
+  nsPopupLevel PopupLevel(bool aIsNoAutoHide) const;
+
+  // redefine to tell the box system not to move the views.
+  virtual uint32_t GetXULLayoutFlags() override;
+
+  void InitPositionFromAnchorAlign(const nsAString& aAnchor,
+                                   const nsAString& aAlign);
+
+  // return the position where the popup should be, when it should be
+  // anchored at anchorRect. aHFlip and aVFlip will be set if the popup may be
+  // flipped in that direction if there is not enough space available.
+  nsPoint AdjustPositionForAnchorAlign(nsRect& anchorRect,
+                                       FlipStyle& aHFlip, FlipStyle& aVFlip);
+
+  // For popups that are going to align to their selected item, get the frame of
+  // the selected item.
+  nsIFrame* GetSelectedItemForAlignment();
+
+  // check if the popup will fit into the available space and resize it. This
+  // method handles only one axis at a time so is called twice, once for
+  // horizontal and once for vertical. All arguments are specified for this
+  // one axis. All coordinates are in app units relative to the screen.
+  //   aScreenPoint - the point where the popup should appear
+  //   aSize - the size of the popup
+  //   aScreenBegin - the left or top edge of the screen
+  //   aScreenEnd - the right or bottom edge of the screen
+  //   aAnchorBegin - the left or top edge of the anchor rectangle
+  //   aAnchorEnd - the right or bottom edge of the anchor rectangle
+  //   aMarginBegin - the left or top margin of the popup
+  //   aMarginEnd - the right or bottom margin of the popup
+  //   aOffsetForContextMenu - the additional offset to add for context menus
+  //   aFlip - how to flip or resize the popup when there isn't space
+  //   aFlipSide - pointer to where current flip mode is stored
+  nscoord FlipOrResize(nscoord& aScreenPoint, nscoord aSize, 
+                       nscoord aScreenBegin, nscoord aScreenEnd,
+                       nscoord aAnchorBegin, nscoord aAnchorEnd,
+                       nscoord aMarginBegin, nscoord aMarginEnd,
+                       nscoord aOffsetForContextMenu, FlipStyle aFlip,
+                       bool aIsOnEnd, bool* aFlipSide);
+
+  // check if the popup can fit into the available space by "sliding" (i.e.,
+  // by having the anchor arrow slide along one axis and only resizing if that
+  // can't provide the requested size). Only one axis can be slid - the other
+  // axis is "flipped" as normal. This method can handle either axis, but is
+  // only called for the sliding axis. All coordinates are in app units
+  // relative to the screen.
+  //   aScreenPoint - the point where the popup should appear
+  //   aSize - the size of the popup
+  //   aScreenBegin - the left or top edge of the screen
+  //   aScreenEnd - the right or bottom edge of the screen
+  //   aOffset - the amount by which the arrow must be slid such that it is
+  //             still aligned with the anchor.
+  // Result is the new size of the popup, which will typically be the same
+  // as aSize, unless aSize is greater than the screen width/height.
+  nscoord SlideOrResize(nscoord& aScreenPoint, nscoord aSize,
+                        nscoord aScreenBegin, nscoord aScreenEnd,
+                        nscoord *aOffset);
+
+  // Move the popup to the position specified in its |left| and |top| attributes.
+  void MoveToAttributePosition();
+
+  /**
+   * Return whether the popup direction should be RTL.
+   * If the popup has an anchor, its direction is the anchor direction.
+   * Otherwise, its the general direction of the UI.
+   *
+   * Return whether the popup direction should be RTL.
+   */
+  bool IsDirectionRTL() const {
+    return mAnchorContent && mAnchorContent->GetPrimaryFrame()
+      ? mAnchorContent->GetPrimaryFrame()->StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL
+      : StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
+  }
+
+  // Create a popup view for this frame. The view is added a child of the root
+  // view, and is initially hidden.
+  void CreatePopupView();
+
+  nsString     mIncrementalString;  // for incremental typing navigation
+
+  // the content that the popup is anchored to, if any, which may be in a
+  // different document than the popup.
+  nsCOMPtr<nsIContent> mAnchorContent;
+
+  // the content that triggered the popup, typically the node where the mouse
+  // was clicked. It will be cleared when the popup is hidden.
+  nsCOMPtr<nsIContent> mTriggerContent;
+
+  nsMenuFrame* mCurrentMenu; // The current menu that is active.
+
+  RefPtr<nsXULPopupShownEvent> mPopupShownDispatcher;
+
+  // The popup's screen rectangle in app units.
+  nsIntRect mUsedScreenRect;
+
+  // A popup's preferred size may be different than its actual size stored in
+  // mRect in the case where the popup was resized because it was too large
+  // for the screen. The preferred size mPrefSize holds the full size the popup
+  // would be before resizing. Computations are performed using this size.
+  nsSize mPrefSize;
+
+  // The position of the popup, in CSS pixels.
+  // The screen coordinates, if set to values other than -1,
+  // override mXPos and mYPos.
+  int32_t mXPos;
+  int32_t mYPos;
+  nsIntRect mScreenRect;
+
+  // If the panel prefers to "slide" rather than resize, then the arrow gets
+  // positioned at this offset (along either the x or y axis, depending on
+  // mPosition)
+  nscoord mAlignmentOffset;
+
+  // The value of the client offset of our widget the last time we positioned
+  // ourselves. We store this so that we can detect when it changes but the
+  // position of our widget didn't change.
+  mozilla::LayoutDeviceIntPoint mLastClientOffset;
+
+  nsPopupType mPopupType; // type of popup
+  nsPopupState mPopupState; // open state of the popup
+
+  // popup alignment relative to the anchor node
+  int8_t mPopupAlignment;
+  int8_t mPopupAnchor;
+  int8_t mPosition;
+
+  // One of PopupBoxObject::ROLLUP_DEFAULT/ROLLUP_CONSUME/ROLLUP_NO_CONSUME
+  uint8_t mConsumeRollupEvent;
+  FlipType mFlip; // Whether to flip
+
+  struct ReflowCallbackData {
+    ReflowCallbackData() :
+      mPosted(false),
+      mAnchor(nullptr),
+      mSizedToPopup(false)
+    {}
+    void MarkPosted(nsIFrame* aAnchor, bool aSizedToPopup) {
+      mPosted = true;
+      mAnchor = aAnchor;
+      mSizedToPopup = aSizedToPopup;
+    }
+    void Clear() {
+      mPosted = false;
+      mAnchor = nullptr;
+      mSizedToPopup = false;
+    }
+    bool mPosted;
+    nsIFrame* mAnchor;
+    bool mSizedToPopup;
+  };
+  ReflowCallbackData mReflowCallbackData;
+
+  bool mIsOpenChanged; // true if the open state changed since the last layout
+  bool mIsContextMenu; // true for context menus
+  // true if we need to offset the popup to ensure it's not under the mouse
+  bool mAdjustOffsetForContextMenu;
+  bool mGeneratedChildren; // true if the contents have been created
+
+  bool mMenuCanOverlapOSBar;    // can we appear over the taskbar/menubar?
+  bool mShouldAutoPosition; // Should SetPopupPosition be allowed to auto position popup?
+  bool mInContentShell; // True if the popup is in a content shell
+  bool mIsMenuLocked; // Should events inside this menu be ignored?
+  bool mMouseTransparent; // True if this is a popup is transparent to mouse events
+
+  // the flip modes that were used when the popup was opened
+  bool mHFlip;
+  bool mVFlip;
+
+  // How the popup is anchored.
+  MenuPopupAnchorType mAnchorType;
+
+  nsRect mOverrideConstraintRect;
+
+  static int8_t sDefaultLevelIsTop;
+
+  static DOMTimeStamp sLastKeyTime;
+
+  // If 0, never timed out.  Otherwise, the value is in milliseconds.
+  static uint32_t sTimeoutOfIncrementalSearch;
+}; // class nsMenuPopupFrame
+
+#endif
diff --git a/layout/xul/nsPIBoxObject.h b/layout/xul/nsPIBoxObject.h
new file mode 100644
index 0000000000..46ec6ea387
--- /dev/null
+++ b/layout/xul/nsPIBoxObject.h
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPIBoxObject_h___
+#define nsPIBoxObject_h___
+
+#include "nsIBoxObject.h"
+
+// {2b8bb262-1b0f-4572-ba87-5d4ae4954445}
+#define NS_PIBOXOBJECT_IID \
+{ 0x2b8bb262, 0x1b0f, 0x4572, \
+  { 0xba, 0x87, 0x5d, 0x4a, 0xe4, 0x95, 0x44, 0x45 } }
+
+
+class nsIContent;
+
+class nsPIBoxObject : public nsIBoxObject
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_PIBOXOBJECT_IID)
+
+  virtual nsresult Init(nsIContent* aContent) = 0;
+
+  // Drop the weak ref to the content node as needed
+  virtual void Clear() = 0;
+
+  // The values cached by the implementation of this interface should be
+  // cleared when this method is called.
+  virtual void ClearCachedValues() = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsPIBoxObject, NS_PIBOXOBJECT_IID)
+
+#endif
+
diff --git a/layout/xul/nsPIListBoxObject.h b/layout/xul/nsPIListBoxObject.h
new file mode 100644
index 0000000000..c7b9928f0d
--- /dev/null
+++ b/layout/xul/nsPIListBoxObject.h
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPIListBoxObject_h__
+#define nsPIListBoxObject_h__
+
+class nsListBoxBodyFrame;
+
+// fa9549f7-ee09-48fc-89f7-30cceee21c15
+#define NS_PILISTBOXOBJECT_IID \
+{ 0xfa9549f7, 0xee09, 0x48fc, \
+  { 0x89, 0xf7, 0x30, 0xcc, 0xee, 0xe2, 0x1c, 0x15 } }
+
+#include "nsIListBoxObject.h"
+
+class nsPIListBoxObject : public nsIListBoxObject {
+ public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_PILISTBOXOBJECT_IID)
+  /**
+   * Get the list box body.  This will search for it as needed.
+   * If aFlush is false we don't Flush_Frames though.
+   */
+  virtual nsListBoxBodyFrame* GetListBoxBody(bool aFlush) = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsPIListBoxObject, NS_PILISTBOXOBJECT_IID)
+
+#endif // nsPIListBoxObject_h__
diff --git a/layout/xul/nsPopupSetFrame.cpp b/layout/xul/nsPopupSetFrame.cpp
new file mode 100644
index 0000000000..a627ee0795
--- /dev/null
+++ b/layout/xul/nsPopupSetFrame.cpp
@@ -0,0 +1,160 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsPopupSetFrame.h"
+#include "nsGkAtoms.h"
+#include "nsCOMPtr.h"
+#include "nsIContent.h"
+#include "nsPresContext.h"
+#include "nsStyleContext.h"
+#include "nsBoxLayoutState.h"
+#include "nsIScrollableFrame.h"
+#include "nsIRootBox.h"
+#include "nsMenuPopupFrame.h"
+
+nsIFrame*
+NS_NewPopupSetFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsPopupSetFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsPopupSetFrame)
+
+void
+nsPopupSetFrame::Init(nsIContent*       aContent,
+                      nsContainerFrame* aParent,
+                      nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  // Normally the root box is our grandparent, but in case of wrapping
+  // it can be our great-grandparent.
+  nsIRootBox *rootBox = nsIRootBox::GetRootBox(PresContext()->GetPresShell());
+  if (rootBox) {
+    rootBox->SetPopupSetFrame(this);
+  }
+}
+
+nsIAtom*
+nsPopupSetFrame::GetType() const
+{
+  return nsGkAtoms::popupSetFrame;
+}
+
+void
+nsPopupSetFrame::AppendFrames(ChildListID     aListID,
+                              nsFrameList&    aFrameList)
+{
+  if (aListID == kPopupList) {
+    AddPopupFrameList(aFrameList);
+    return;
+  }
+  nsBoxFrame::AppendFrames(aListID, aFrameList);
+}
+
+void
+nsPopupSetFrame::RemoveFrame(ChildListID     aListID,
+                             nsIFrame*       aOldFrame)
+{
+  if (aListID == kPopupList) {
+    RemovePopupFrame(aOldFrame);
+    return;
+  }
+  nsBoxFrame::RemoveFrame(aListID, aOldFrame);
+}
+
+void
+nsPopupSetFrame::InsertFrames(ChildListID     aListID,
+                              nsIFrame*       aPrevFrame,
+                              nsFrameList&    aFrameList)
+{
+  if (aListID == kPopupList) {
+    AddPopupFrameList(aFrameList);
+    return;
+  }
+  nsBoxFrame::InsertFrames(aListID, aPrevFrame, aFrameList);
+}
+
+void
+nsPopupSetFrame::SetInitialChildList(ChildListID     aListID,
+                                     nsFrameList&    aChildList)
+{
+  if (aListID == kPopupList) {
+    NS_ASSERTION(mPopupList.IsEmpty(),
+                 "SetInitialChildList on non-empty child list");
+    AddPopupFrameList(aChildList);
+    return;
+  }
+  nsBoxFrame::SetInitialChildList(aListID, aChildList);
+}
+
+const nsFrameList&
+nsPopupSetFrame::GetChildList(ChildListID aListID) const
+{
+  if (kPopupList == aListID) {
+    return mPopupList;
+  }
+  return nsBoxFrame::GetChildList(aListID);
+}
+
+void
+nsPopupSetFrame::GetChildLists(nsTArray<ChildList>* aLists) const
+{
+  nsBoxFrame::GetChildLists(aLists);
+  mPopupList.AppendIfNonempty(aLists, kPopupList);
+}
+
+void
+nsPopupSetFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  mPopupList.DestroyFramesFrom(aDestructRoot);
+
+  // Normally the root box is our grandparent, but in case of wrapping
+  // it can be our great-grandparent.
+  nsIRootBox *rootBox = nsIRootBox::GetRootBox(PresContext()->GetPresShell());
+  if (rootBox) {
+    rootBox->SetPopupSetFrame(nullptr);
+  }
+
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+NS_IMETHODIMP
+nsPopupSetFrame::DoXULLayout(nsBoxLayoutState& aState)
+{
+  // lay us out
+  nsresult rv = nsBoxFrame::DoXULLayout(aState);
+
+  // lay out all of our currently open popups.
+  for (nsFrameList::Enumerator e(mPopupList); !e.AtEnd(); e.Next()) {
+    nsMenuPopupFrame* popupChild = static_cast<nsMenuPopupFrame*>(e.get());
+    popupChild->LayoutPopup(aState, nullptr, nullptr, false);
+  }
+
+  return rv;
+}
+
+void
+nsPopupSetFrame::RemovePopupFrame(nsIFrame* aPopup)
+{
+  NS_PRECONDITION((aPopup->GetStateBits() & NS_FRAME_OUT_OF_FLOW) &&
+                  aPopup->GetType() == nsGkAtoms::menuPopupFrame,
+                  "removing wrong type of frame in popupset's ::popupList");
+
+  mPopupList.DestroyFrame(aPopup);
+}
+
+void
+nsPopupSetFrame::AddPopupFrameList(nsFrameList& aPopupFrameList)
+{
+#ifdef DEBUG
+  for (nsFrameList::Enumerator e(aPopupFrameList); !e.AtEnd(); e.Next()) {
+    NS_ASSERTION((e.get()->GetStateBits() & NS_FRAME_OUT_OF_FLOW) &&
+                 e.get()->GetType() == nsGkAtoms::menuPopupFrame,
+                 "adding wrong type of frame in popupset's ::popupList");
+  }
+#endif
+  mPopupList.InsertFrames(nullptr, nullptr, aPopupFrameList);
+}
diff --git a/layout/xul/nsPopupSetFrame.h b/layout/xul/nsPopupSetFrame.h
new file mode 100644
index 0000000000..1981b996d3
--- /dev/null
+++ b/layout/xul/nsPopupSetFrame.h
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsPopupSetFrame_h__
+#define nsPopupSetFrame_h__
+
+#include "mozilla/Attributes.h"
+#include "nsIAtom.h"
+#include "nsBoxFrame.h"
+
+nsIFrame* NS_NewPopupSetFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+class nsPopupSetFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  explicit nsPopupSetFrame(nsStyleContext* aContext):
+    nsBoxFrame(aContext) {}
+
+  ~nsPopupSetFrame() {}
+  
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual void SetInitialChildList(ChildListID  aListID,
+                                    nsFrameList& aChildList) override;
+  virtual void AppendFrames(ChildListID     aListID,
+                            nsFrameList&    aFrameList) override;
+  virtual void RemoveFrame(ChildListID     aListID,
+                           nsIFrame*       aOldFrame) override;
+  virtual void InsertFrames(ChildListID     aListID,
+                            nsIFrame*       aPrevFrame,
+                            nsFrameList&    aFrameList) override;
+
+  virtual const nsFrameList& GetChildList(ChildListID aList) const override;
+  virtual void GetChildLists(nsTArray<ChildList>* aLists) const override;
+
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aBoxLayoutState) override;
+
+  // Used to destroy our popup frames.
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual nsIAtom* GetType() const override;
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override
+  {
+      return MakeFrameName(NS_LITERAL_STRING("PopupSet"), aResult);
+  }
+#endif
+
+protected:
+  void AddPopupFrameList(nsFrameList& aPopupFrameList);
+  void RemovePopupFrame(nsIFrame* aPopup);
+  
+  nsFrameList mPopupList;
+};
+
+#endif
diff --git a/layout/xul/nsProgressMeterFrame.cpp b/layout/xul/nsProgressMeterFrame.cpp
new file mode 100644
index 0000000000..a798d57178
--- /dev/null
+++ b/layout/xul/nsProgressMeterFrame.cpp
@@ -0,0 +1,184 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// David Hyatt & Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsProgressMeterFrame.h"
+#include "nsCSSRendering.h"
+#include "nsIContent.h"
+#include "nsPresContext.h"
+#include "nsGkAtoms.h"
+#include "nsNameSpaceManager.h"
+#include "nsCOMPtr.h"
+#include "nsBoxLayoutState.h"
+#include "nsIReflowCallback.h"
+#include "nsContentUtils.h"
+#include "mozilla/Attributes.h"
+
+class nsReflowFrameRunnable : public mozilla::Runnable
+{
+public:
+  nsReflowFrameRunnable(nsIFrame* aFrame,
+                        nsIPresShell::IntrinsicDirty aIntrinsicDirty,
+                        nsFrameState aBitToAdd);
+
+  NS_DECL_NSIRUNNABLE
+
+  nsWeakFrame mWeakFrame;
+  nsIPresShell::IntrinsicDirty mIntrinsicDirty;
+  nsFrameState mBitToAdd;
+};
+
+nsReflowFrameRunnable::nsReflowFrameRunnable(nsIFrame* aFrame,
+                          nsIPresShell::IntrinsicDirty aIntrinsicDirty,
+                          nsFrameState aBitToAdd)
+  : mWeakFrame(aFrame),
+    mIntrinsicDirty(aIntrinsicDirty),
+    mBitToAdd(aBitToAdd)
+{
+}
+
+NS_IMETHODIMP
+nsReflowFrameRunnable::Run()
+{
+  if (mWeakFrame.IsAlive()) {
+    mWeakFrame->PresContext()->PresShell()->
+      FrameNeedsReflow(mWeakFrame, mIntrinsicDirty, mBitToAdd);
+  }
+  return NS_OK;
+}
+
+//
+// NS_NewToolbarFrame
+//
+// Creates a new Toolbar frame and returns it
+//
+nsIFrame*
+NS_NewProgressMeterFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsProgressMeterFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsProgressMeterFrame)
+
+//
+// nsProgressMeterFrame dstr
+//
+// Cleanup, if necessary
+//
+nsProgressMeterFrame :: ~nsProgressMeterFrame ( )
+{
+}
+
+class nsAsyncProgressMeterInit final : public nsIReflowCallback
+{
+public:
+  explicit nsAsyncProgressMeterInit(nsIFrame* aFrame) : mWeakFrame(aFrame) {}
+
+  virtual bool ReflowFinished() override
+  {
+    bool shouldFlush = false;
+    nsIFrame* frame = mWeakFrame.GetFrame();
+    if (frame) {
+      nsAutoScriptBlocker scriptBlocker;
+      frame->AttributeChanged(kNameSpaceID_None, nsGkAtoms::mode, 0);
+      shouldFlush = true;
+    }
+    delete this;
+    return shouldFlush;
+  }
+
+  virtual void ReflowCallbackCanceled() override
+  {
+    delete this;
+  }
+
+  nsWeakFrame mWeakFrame;
+};
+
+NS_IMETHODIMP
+nsProgressMeterFrame::DoXULLayout(nsBoxLayoutState& aState)
+{
+  if (mNeedsReflowCallback) {
+    nsIReflowCallback* cb = new nsAsyncProgressMeterInit(this);
+    if (cb) {
+      PresContext()->PresShell()->PostReflowCallback(cb);
+    }
+    mNeedsReflowCallback = false;
+  }
+  return nsBoxFrame::DoXULLayout(aState);
+}
+
+nsresult
+nsProgressMeterFrame::AttributeChanged(int32_t aNameSpaceID,
+                                       nsIAtom* aAttribute,
+                                       int32_t aModType)
+{
+  NS_ASSERTION(!nsContentUtils::IsSafeToRunScript(),
+      "Scripts not blocked in nsProgressMeterFrame::AttributeChanged!");
+  nsresult rv = nsBoxFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                             aModType);
+  if (NS_OK != rv) {
+    return rv;
+  }
+
+  // did the progress change?
+  bool undetermined = mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::mode,
+                                            nsGkAtoms::undetermined, eCaseMatters);
+  if (nsGkAtoms::mode == aAttribute ||
+      (!undetermined &&
+       (nsGkAtoms::value == aAttribute || nsGkAtoms::max == aAttribute))) {
+    nsIFrame* barChild = PrincipalChildList().FirstChild();
+    if (!barChild) return NS_OK;
+    nsIFrame* remainderChild = barChild->GetNextSibling();
+    if (!remainderChild) return NS_OK;
+    nsCOMPtr<nsIContent> remainderContent = remainderChild->GetContent();
+    if (!remainderContent) return NS_OK;
+
+    int32_t flex = 1, maxFlex = 1;
+    if (!undetermined) {
+      nsAutoString value, maxValue;
+      mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::value, value);
+      mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::max, maxValue);
+
+      nsresult error;
+      flex = value.ToInteger(&error);
+      maxFlex = maxValue.ToInteger(&error);
+      if (NS_FAILED(error) || maxValue.IsEmpty()) {
+        maxFlex = 100;
+      }
+      if (maxFlex < 1) {
+        maxFlex = 1;
+      }
+      if (flex < 0) {
+        flex = 0;
+      }
+      if (flex > maxFlex) {
+        flex = maxFlex;
+      }
+    }
+
+    nsContentUtils::AddScriptRunner(new nsSetAttrRunnable(
+      barChild->GetContent(), nsGkAtoms::flex, flex));
+    nsContentUtils::AddScriptRunner(new nsSetAttrRunnable(
+      remainderContent, nsGkAtoms::flex, maxFlex - flex));
+    nsContentUtils::AddScriptRunner(new nsReflowFrameRunnable(
+      this, nsIPresShell::eTreeChange, NS_FRAME_IS_DIRTY));
+  }
+  return NS_OK;
+}
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+nsProgressMeterFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("ProgressMeter"), aResult);
+}
+#endif
diff --git a/layout/xul/nsProgressMeterFrame.h b/layout/xul/nsProgressMeterFrame.h
new file mode 100644
index 0000000000..0a4af7ff41
--- /dev/null
+++ b/layout/xul/nsProgressMeterFrame.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+
+  David Hyatt & Eric D Vaughan.
+
+  An XBL-based progress meter. 
+
+  Attributes:
+
+  value: A number between 0% and 100%
+  align: horizontal or vertical
+  mode: determined, undetermined (one shows progress other shows animated candy cane)
+
+**/
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+class nsProgressMeterFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewProgressMeterFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aBoxLayoutState) override;
+
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override;
+#endif
+
+protected:
+  explicit nsProgressMeterFrame(nsStyleContext* aContext) :
+    nsBoxFrame(aContext), mNeedsReflowCallback(true) {}
+  virtual ~nsProgressMeterFrame();
+
+  bool mNeedsReflowCallback;
+}; // class nsProgressMeterFrame
diff --git a/layout/xul/nsRepeatService.cpp b/layout/xul/nsRepeatService.cpp
new file mode 100644
index 0000000000..919763d4dc
--- /dev/null
+++ b/layout/xul/nsRepeatService.cpp
@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsRepeatService.h"
+#include "nsIServiceManager.h"
+
+nsRepeatService* nsRepeatService::gInstance = nullptr;
+
+nsRepeatService::nsRepeatService()
+: mCallback(nullptr), mCallbackData(nullptr)
+{
+}
+
+nsRepeatService::~nsRepeatService()
+{
+  NS_ASSERTION(!mCallback && !mCallbackData, "Callback was not removed before shutdown");
+}
+
+nsRepeatService* 
+nsRepeatService::GetInstance()
+{
+  if (!gInstance) {
+    gInstance = new nsRepeatService();
+    NS_IF_ADDREF(gInstance);
+  }
+  return gInstance;
+}
+
+/*static*/ void
+nsRepeatService::Shutdown()
+{
+  NS_IF_RELEASE(gInstance);
+}
+
+void nsRepeatService::Start(Callback aCallback, void* aCallbackData,
+                            uint32_t aInitialDelay)
+{
+  NS_PRECONDITION(aCallback != nullptr, "null ptr");
+
+  mCallback = aCallback;
+  mCallbackData = aCallbackData;
+  nsresult rv;
+  mRepeatTimer = do_CreateInstance("@mozilla.org/timer;1", &rv);
+
+  if (NS_SUCCEEDED(rv))  {
+    mRepeatTimer->InitWithCallback(this, aInitialDelay, nsITimer::TYPE_ONE_SHOT);
+  }
+}
+
+void nsRepeatService::Stop(Callback aCallback, void* aCallbackData)
+{
+  if (mCallback != aCallback || mCallbackData != aCallbackData)
+    return;
+
+  //printf("Stopping repeat timer\n");
+  if (mRepeatTimer) {
+     mRepeatTimer->Cancel();
+     mRepeatTimer = nullptr;
+  }
+  mCallback = nullptr;
+  mCallbackData = nullptr;
+}
+
+NS_IMETHODIMP nsRepeatService::Notify(nsITimer *timer)
+{
+  // do callback
+  if (mCallback)
+    mCallback(mCallbackData);
+
+  // start timer again.
+  if (mRepeatTimer) {
+    mRepeatTimer->InitWithCallback(this, REPEAT_DELAY, nsITimer::TYPE_ONE_SHOT);
+  }
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(nsRepeatService, nsITimerCallback)
diff --git a/layout/xul/nsRepeatService.h b/layout/xul/nsRepeatService.h
new file mode 100644
index 0000000000..81321a4729
--- /dev/null
+++ b/layout/xul/nsRepeatService.h
@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// nsRepeatService
+//
+#ifndef nsRepeatService_h__
+#define nsRepeatService_h__
+
+#include "nsCOMPtr.h"
+#include "nsITimer.h"
+
+#define INITAL_REPEAT_DELAY 250
+
+#ifdef XP_MACOSX
+#define REPEAT_DELAY        25
+#else
+#define REPEAT_DELAY        50
+#endif
+
+class nsITimer;
+
+class nsRepeatService final : public nsITimerCallback
+{
+public:
+
+  typedef void (* Callback)(void* aData);
+    
+  NS_DECL_NSITIMERCALLBACK
+
+  // Start dispatching timer events to the callback. There is no memory
+  // management of aData here; it is the caller's responsibility to call
+  // Stop() before aData's memory is released.
+  void Start(Callback aCallback, void* aData,
+             uint32_t aInitialDelay = INITAL_REPEAT_DELAY);
+  // Stop dispatching timer events to the callback. If the repeat service
+  // is not currently configured with the given callback and data, this
+  // is just ignored.
+  void Stop(Callback aCallback, void* aData);
+
+  static nsRepeatService* GetInstance();
+  static void Shutdown();
+
+  NS_DECL_ISUPPORTS
+
+protected:
+  nsRepeatService();
+  virtual ~nsRepeatService();
+
+private:
+  Callback           mCallback;
+  void*              mCallbackData;
+  nsCOMPtr<nsITimer> mRepeatTimer;
+  static nsRepeatService* gInstance;
+
+}; // class nsRepeatService
+
+#endif
diff --git a/layout/xul/nsResizerFrame.cpp b/layout/xul/nsResizerFrame.cpp
new file mode 100644
index 0000000000..b32b84fe50
--- /dev/null
+++ b/layout/xul/nsResizerFrame.cpp
@@ -0,0 +1,538 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsAutoPtr.h"
+#include "nsCOMPtr.h"
+#include "nsIServiceManager.h"
+#include "nsResizerFrame.h"
+#include "nsIContent.h"
+#include "nsIDocument.h"
+#include "nsIDOMNodeList.h"
+#include "nsGkAtoms.h"
+#include "nsNameSpaceManager.h"
+#include "nsIDOMCSSStyleDeclaration.h"
+
+#include "nsPresContext.h"
+#include "nsFrameManager.h"
+#include "nsIDocShell.h"
+#include "nsIDocShellTreeOwner.h"
+#include "nsIBaseWindow.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/MouseEvents.h"
+#include "nsContentUtils.h"
+#include "nsMenuPopupFrame.h"
+#include "nsIScreenManager.h"
+#include "mozilla/dom/Element.h"
+#include "nsError.h"
+#include "nsICSSDeclaration.h"
+#include "nsStyledElement.h"
+#include <algorithm>
+
+using namespace mozilla;
+
+//
+// NS_NewResizerFrame
+//
+// Creates a new Resizer frame and returns it
+//
+nsIFrame*
+NS_NewResizerFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsResizerFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsResizerFrame)
+
+nsResizerFrame::nsResizerFrame(nsStyleContext* aContext)
+:nsTitleBarFrame(aContext)
+{
+}
+
+nsresult
+nsResizerFrame::HandleEvent(nsPresContext* aPresContext,
+                            WidgetGUIEvent* aEvent,
+                            nsEventStatus* aEventStatus)
+{
+  NS_ENSURE_ARG_POINTER(aEventStatus);
+  if (nsEventStatus_eConsumeNoDefault == *aEventStatus) {
+    return NS_OK;
+  }
+
+  nsWeakFrame weakFrame(this);
+  bool doDefault = true;
+
+  switch (aEvent->mMessage) {
+    case eTouchStart:
+    case eMouseDown: {
+      if (aEvent->mClass == eTouchEventClass ||
+          (aEvent->mClass == eMouseEventClass &&
+           aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton)) {
+        nsCOMPtr<nsIBaseWindow> window;
+        nsIPresShell* presShell = aPresContext->GetPresShell();
+        nsIContent* contentToResize =
+          GetContentToResize(presShell, getter_AddRefs(window));
+        if (contentToResize) {
+          nsIFrame* frameToResize = contentToResize->GetPrimaryFrame();
+          if (!frameToResize)
+            break;
+
+          // cache the content rectangle for the frame to resize
+          // GetScreenRectInAppUnits returns the border box rectangle, so
+          // adjust to get the desired content rectangle.
+          nsRect rect = frameToResize->GetScreenRectInAppUnits();
+          if (frameToResize->StylePosition()->mBoxSizing == StyleBoxSizing::Content) {
+            rect.Deflate(frameToResize->GetUsedBorderAndPadding());
+          }
+
+          mMouseDownRect =
+            LayoutDeviceIntRect::FromAppUnitsToNearest(rect, aPresContext->AppUnitsPerDevPixel());
+          doDefault = false;
+        }
+        else {
+          // If there is no window, then resizing isn't allowed.
+          if (!window)
+            break;
+
+          doDefault = false;
+
+          // ask the widget implementation to begin a resize drag if it can
+          Direction direction = GetDirection();
+          nsresult rv = aEvent->mWidget->BeginResizeDrag(aEvent,
+                        direction.mHorizontal, direction.mVertical);
+          // for native drags, don't set the fields below
+          if (rv != NS_ERROR_NOT_IMPLEMENTED)
+             break;
+             
+          // if there's no native resize support, we need to do window
+          // resizing ourselves
+          window->GetPositionAndSize(&mMouseDownRect.x, &mMouseDownRect.y,
+                                     &mMouseDownRect.width, &mMouseDownRect.height);
+        }
+
+        // remember current mouse coordinates
+        LayoutDeviceIntPoint refPoint;
+        if (!GetEventPoint(aEvent, refPoint))
+          return NS_OK;
+        mMouseDownPoint = refPoint + aEvent->mWidget->WidgetToScreenOffset();
+
+        // we're tracking
+        mTrackingMouseMove = true;
+
+        nsIPresShell::SetCapturingContent(GetContent(), CAPTURE_IGNOREALLOWED);
+      }
+    }
+    break;
+
+  case eTouchEnd:
+  case eMouseUp: {
+    if (aEvent->mClass == eTouchEventClass ||
+        (aEvent->mClass == eMouseEventClass &&
+         aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton)) {
+      // we're done tracking.
+      mTrackingMouseMove = false;
+
+      nsIPresShell::SetCapturingContent(nullptr, 0);
+
+      doDefault = false;
+    }
+  }
+  break;
+
+  case eTouchMove:
+  case eMouseMove: {
+    if (mTrackingMouseMove)
+    {
+      nsCOMPtr<nsIBaseWindow> window;
+      nsIPresShell* presShell = aPresContext->GetPresShell();
+      nsCOMPtr<nsIContent> contentToResize =
+        GetContentToResize(presShell, getter_AddRefs(window));
+
+      // check if the returned content really is a menupopup
+      nsMenuPopupFrame* menuPopupFrame = nullptr;
+      if (contentToResize) {
+        menuPopupFrame = do_QueryFrame(contentToResize->GetPrimaryFrame());
+      }
+
+      // both MouseMove and direction are negative when pointing to the
+      // top and left, and positive when pointing to the bottom and right
+
+      // retrieve the offset of the mousemove event relative to the mousedown.
+      // The difference is how much the resize needs to be
+      LayoutDeviceIntPoint refPoint;
+      if (!GetEventPoint(aEvent, refPoint))
+        return NS_OK;
+      LayoutDeviceIntPoint screenPoint =
+        refPoint + aEvent->mWidget->WidgetToScreenOffset();
+      LayoutDeviceIntPoint mouseMove(screenPoint - mMouseDownPoint);
+
+      // Determine which direction to resize by checking the dir attribute.
+      // For windows and menus, ensure that it can be resized in that direction.
+      Direction direction = GetDirection();
+      if (window || menuPopupFrame) {
+        if (menuPopupFrame) {
+          menuPopupFrame->CanAdjustEdges(
+            (direction.mHorizontal == -1) ? NS_SIDE_LEFT : NS_SIDE_RIGHT,
+            (direction.mVertical == -1) ? NS_SIDE_TOP : NS_SIDE_BOTTOM, mouseMove);
+        }
+      }
+      else if (!contentToResize) {
+        break; // don't do anything if there's nothing to resize
+      }
+
+      LayoutDeviceIntRect rect = mMouseDownRect;
+
+      // Check if there are any size constraints on this window.
+      widget::SizeConstraints sizeConstraints;
+      if (window) {
+        nsCOMPtr<nsIWidget> widget;
+        window->GetMainWidget(getter_AddRefs(widget));
+        sizeConstraints = widget->GetSizeConstraints();
+      }
+
+      AdjustDimensions(&rect.x, &rect.width, sizeConstraints.mMinSize.width,
+                       sizeConstraints.mMaxSize.width, mouseMove.x, direction.mHorizontal);
+      AdjustDimensions(&rect.y, &rect.height, sizeConstraints.mMinSize.height,
+                       sizeConstraints.mMaxSize.height, mouseMove.y, direction.mVertical);
+
+      // Don't allow resizing a window or a popup past the edge of the screen,
+      // so adjust the rectangle to fit within the available screen area.
+      if (window) {
+        nsCOMPtr<nsIScreen> screen;
+        nsCOMPtr<nsIScreenManager> sm(do_GetService("@mozilla.org/gfx/screenmanager;1"));
+        if (sm) {
+          nsIntRect frameRect = GetScreenRect();
+          // ScreenForRect requires display pixels, so scale from device pix
+          double scale;
+          window->GetUnscaledDevicePixelsPerCSSPixel(&scale);
+          sm->ScreenForRect(NSToIntRound(frameRect.x / scale),
+                            NSToIntRound(frameRect.y / scale), 1, 1,
+                            getter_AddRefs(screen));
+          if (screen) {
+            LayoutDeviceIntRect screenRect;
+            screen->GetRect(&screenRect.x, &screenRect.y,
+                            &screenRect.width, &screenRect.height);
+            rect.IntersectRect(rect, screenRect);
+          }
+        }
+      }
+      else if (menuPopupFrame) {
+        nsRect frameRect = menuPopupFrame->GetScreenRectInAppUnits();
+        nsIFrame* rootFrame = aPresContext->PresShell()->FrameManager()->GetRootFrame();
+        nsRect rootScreenRect = rootFrame->GetScreenRectInAppUnits();
+
+        nsPopupLevel popupLevel = menuPopupFrame->PopupLevel();
+        int32_t appPerDev = aPresContext->AppUnitsPerDevPixel();
+        LayoutDeviceIntRect screenRect = menuPopupFrame->GetConstraintRect
+          (LayoutDeviceIntRect::FromAppUnitsToNearest(frameRect, appPerDev),
+           // round using ...ToInside as it's better to be a pixel too small
+           // than be too large. If the popup is too large it could get flipped
+           // to the opposite side of the anchor point while resizing.
+           LayoutDeviceIntRect::FromAppUnitsToInside(rootScreenRect, appPerDev),
+           popupLevel);
+        rect.IntersectRect(rect, screenRect);
+      }
+
+      if (contentToResize) {
+        // convert the rectangle into css pixels. When changing the size in a
+        // direction, don't allow the new size to be less that the resizer's
+        // size. This ensures that content isn't resized too small as to make
+        // the resizer invisible.
+        nsRect appUnitsRect = ToAppUnits(rect.ToUnknownRect(), aPresContext->AppUnitsPerDevPixel());
+        if (appUnitsRect.width < mRect.width && mouseMove.x)
+          appUnitsRect.width = mRect.width;
+        if (appUnitsRect.height < mRect.height && mouseMove.y)
+          appUnitsRect.height = mRect.height;
+        nsIntRect cssRect = appUnitsRect.ToInsidePixels(nsPresContext::AppUnitsPerCSSPixel());
+
+        LayoutDeviceIntRect oldRect;
+        nsWeakFrame weakFrame(menuPopupFrame);
+        if (menuPopupFrame) {
+          nsCOMPtr<nsIWidget> widget = menuPopupFrame->GetWidget();
+          if (widget)
+            oldRect = widget->GetScreenBounds();
+
+          // convert the new rectangle into outer window coordinates
+          LayoutDeviceIntPoint clientOffset = widget->GetClientOffset();
+          rect.x -= clientOffset.x;
+          rect.y -= clientOffset.y;
+        }
+
+        SizeInfo sizeInfo, originalSizeInfo;
+        sizeInfo.width.AppendInt(cssRect.width);
+        sizeInfo.height.AppendInt(cssRect.height);
+        ResizeContent(contentToResize, direction, sizeInfo, &originalSizeInfo);
+        MaybePersistOriginalSize(contentToResize, originalSizeInfo);
+
+        // Move the popup to the new location unless it is anchored, since
+        // the position shouldn't change. nsMenuPopupFrame::SetPopupPosition
+        // will instead ensure that the popup's position is anchored at the
+        // right place.
+        if (weakFrame.IsAlive() &&
+            (oldRect.x != rect.x || oldRect.y != rect.y) &&
+            (!menuPopupFrame->IsAnchored() ||
+             menuPopupFrame->PopupLevel() != ePopupLevelParent)) {
+
+          CSSPoint cssPos = rect.TopLeft() / aPresContext->CSSToDevPixelScale();
+          menuPopupFrame->MoveTo(RoundedToInt(cssPos), true);
+        }
+      }
+      else {
+        window->SetPositionAndSize(rect.x, rect.y, rect.width, rect.height,
+                                   nsIBaseWindow::eRepaint); // do the repaint.
+      }
+
+      doDefault = false;
+    }
+  }
+  break;
+
+  case eMouseClick: {
+    WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+    if (mouseEvent->IsLeftClickEvent()) {
+      MouseClicked(mouseEvent);
+    }
+    break;
+  }
+  case eMouseDoubleClick:
+    if (aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton) {
+      nsCOMPtr<nsIBaseWindow> window;
+      nsIPresShell* presShell = aPresContext->GetPresShell();
+      nsIContent* contentToResize =
+        GetContentToResize(presShell, getter_AddRefs(window));
+      if (contentToResize) {
+        nsMenuPopupFrame* menuPopupFrame = do_QueryFrame(contentToResize->GetPrimaryFrame());
+        if (menuPopupFrame)
+          break; // Don't restore original sizing for menupopup frames until
+                 // we handle screen constraints here. (Bug 357725)
+
+        RestoreOriginalSize(contentToResize);
+      }
+    }
+    break;
+
+  default:
+    break;
+  }
+
+  if (!doDefault)
+    *aEventStatus = nsEventStatus_eConsumeNoDefault;
+
+  if (doDefault && weakFrame.IsAlive())
+    return nsTitleBarFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+
+  return NS_OK;
+}
+
+nsIContent*
+nsResizerFrame::GetContentToResize(nsIPresShell* aPresShell, nsIBaseWindow** aWindow)
+{
+  *aWindow = nullptr;
+
+  nsAutoString elementid;
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::element, elementid);
+  if (elementid.IsEmpty()) {
+    // If the resizer is in a popup, resize the popup's widget, otherwise
+    // resize the widget associated with the window.
+    nsIFrame* popup = GetParent();
+    while (popup) {
+      nsMenuPopupFrame* popupFrame = do_QueryFrame(popup);
+      if (popupFrame) {
+        return popupFrame->GetContent();
+      }
+      popup = popup->GetParent();
+    }
+
+    // don't allow resizing windows in content shells
+    nsCOMPtr<nsIDocShellTreeItem> dsti = aPresShell->GetPresContext()->GetDocShell();
+    if (!dsti || dsti->ItemType() != nsIDocShellTreeItem::typeChrome) {
+      // don't allow resizers in content shells, except for the viewport
+      // scrollbar which doesn't have a parent
+      nsIContent* nonNativeAnon = mContent->FindFirstNonChromeOnlyAccessContent();
+      if (!nonNativeAnon || nonNativeAnon->GetParent()) {
+        return nullptr;
+      }
+    }
+
+    // get the document and the window - should this be cached?
+    if (nsPIDOMWindowOuter* domWindow = aPresShell->GetDocument()->GetWindow()) {
+      nsCOMPtr<nsIDocShell> docShell = domWindow->GetDocShell();
+      if (docShell) {
+        nsCOMPtr<nsIDocShellTreeOwner> treeOwner;
+        docShell->GetTreeOwner(getter_AddRefs(treeOwner));
+        if (treeOwner) {
+          CallQueryInterface(treeOwner, aWindow);
+        }
+      }
+    }
+
+    return nullptr;
+  }
+
+  if (elementid.EqualsLiteral("_parent")) {
+    // return the parent, but skip over native anonymous content
+    nsIContent* parent = mContent->GetParent();
+    return parent ? parent->FindFirstNonChromeOnlyAccessContent() : nullptr;
+  }
+
+  return aPresShell->GetDocument()->GetElementById(elementid);
+}
+
+void
+nsResizerFrame::AdjustDimensions(int32_t* aPos, int32_t* aSize,
+                                 int32_t aMinSize, int32_t aMaxSize,
+                                 int32_t aMovement, int8_t aResizerDirection)
+{
+  int32_t oldSize = *aSize;
+
+  *aSize += aResizerDirection * aMovement;
+  // use one as a minimum size or the element could disappear
+  if (*aSize < 1)
+    *aSize = 1;
+
+  // Constrain the size within the minimum and maximum size.
+  *aSize = std::max(aMinSize, std::min(aMaxSize, *aSize));
+
+  // For left and top resizers, the window must be moved left by the same
+  // amount that the window was resized.
+  if (aResizerDirection == -1)
+    *aPos += oldSize - *aSize;
+}
+
+/* static */ void
+nsResizerFrame::ResizeContent(nsIContent* aContent, const Direction& aDirection,
+                              const SizeInfo& aSizeInfo, SizeInfo* aOriginalSizeInfo)
+{
+  // for XUL elements, just set the width and height attributes. For
+  // other elements, set style.width and style.height
+  if (aContent->IsXULElement()) {
+    if (aOriginalSizeInfo) {
+      aContent->GetAttr(kNameSpaceID_None, nsGkAtoms::width,
+                        aOriginalSizeInfo->width);
+      aContent->GetAttr(kNameSpaceID_None, nsGkAtoms::height,
+                        aOriginalSizeInfo->height);
+    }
+    // only set the property if the element could have changed in that direction
+    if (aDirection.mHorizontal) {
+      aContent->SetAttr(kNameSpaceID_None, nsGkAtoms::width, aSizeInfo.width, true);
+    }
+    if (aDirection.mVertical) {
+      aContent->SetAttr(kNameSpaceID_None, nsGkAtoms::height, aSizeInfo.height, true);
+    }
+  }
+  else {
+    nsCOMPtr<nsStyledElement> inlineStyleContent =
+      do_QueryInterface(aContent);
+    if (inlineStyleContent) {
+      nsICSSDeclaration* decl = inlineStyleContent->Style();
+
+      if (aOriginalSizeInfo) {
+        decl->GetPropertyValue(NS_LITERAL_STRING("width"),
+                               aOriginalSizeInfo->width);
+        decl->GetPropertyValue(NS_LITERAL_STRING("height"),
+                               aOriginalSizeInfo->height);
+      }
+
+      // only set the property if the element could have changed in that direction
+      if (aDirection.mHorizontal) {
+        nsAutoString widthstr(aSizeInfo.width);
+        if (!widthstr.IsEmpty() &&
+            !Substring(widthstr, widthstr.Length() - 2, 2).EqualsLiteral("px"))
+          widthstr.AppendLiteral("px");
+        decl->SetProperty(NS_LITERAL_STRING("width"), widthstr, EmptyString());
+      }
+      if (aDirection.mVertical) {
+        nsAutoString heightstr(aSizeInfo.height);
+        if (!heightstr.IsEmpty() &&
+            !Substring(heightstr, heightstr.Length() - 2, 2).EqualsLiteral("px"))
+          heightstr.AppendLiteral("px");
+        decl->SetProperty(NS_LITERAL_STRING("height"), heightstr, EmptyString());
+      }
+    }
+  }
+}
+
+/* static */ void
+nsResizerFrame::MaybePersistOriginalSize(nsIContent* aContent,
+                                         const SizeInfo& aSizeInfo)
+{
+  nsresult rv;
+
+  aContent->GetProperty(nsGkAtoms::_moz_original_size, &rv);
+  if (rv != NS_PROPTABLE_PROP_NOT_THERE)
+    return;
+
+  nsAutoPtr<SizeInfo> sizeInfo(new SizeInfo(aSizeInfo));
+  rv = aContent->SetProperty(nsGkAtoms::_moz_original_size, sizeInfo.get(),
+                             nsINode::DeleteProperty<nsResizerFrame::SizeInfo>);
+  if (NS_SUCCEEDED(rv))
+    sizeInfo.forget();
+}
+
+/* static */ void
+nsResizerFrame::RestoreOriginalSize(nsIContent* aContent)
+{
+  nsresult rv;
+  SizeInfo* sizeInfo =
+    static_cast<SizeInfo*>(aContent->GetProperty(nsGkAtoms::_moz_original_size,
+                           &rv));
+  if (NS_FAILED(rv))
+    return;
+
+  NS_ASSERTION(sizeInfo, "We set a null sizeInfo!?");
+  Direction direction = {1, 1};
+  ResizeContent(aContent, direction, *sizeInfo, nullptr);
+  aContent->DeleteProperty(nsGkAtoms::_moz_original_size);
+}
+
+/* returns a Direction struct containing the horizontal and vertical direction
+ */
+nsResizerFrame::Direction
+nsResizerFrame::GetDirection()
+{
+  static const nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::topleft,    &nsGkAtoms::top,    &nsGkAtoms::topright,
+     &nsGkAtoms::left,                           &nsGkAtoms::right,
+     &nsGkAtoms::bottomleft, &nsGkAtoms::bottom, &nsGkAtoms::bottomright,
+     &nsGkAtoms::bottomstart,                    &nsGkAtoms::bottomend,
+     nullptr};
+
+  static const Direction directions[] =
+    {{-1, -1}, {0, -1}, {1, -1},
+     {-1,  0},          {1,  0},
+     {-1,  1}, {0,  1}, {1,  1},
+     {-1,  1},          {1,  1}
+    };
+
+  if (!GetContent()) {
+    return directions[0]; // default: topleft
+  }
+
+  int32_t index = GetContent()->FindAttrValueIn(kNameSpaceID_None,
+                                                nsGkAtoms::dir,
+                                                strings, eCaseMatters);
+  if (index < 0) {
+    return directions[0]; // default: topleft
+  }
+
+  if (index >= 8) {
+    // Directions 8 and higher are RTL-aware directions and should reverse the
+    // horizontal component if RTL.
+    WritingMode wm = GetWritingMode();
+    if (!(wm.IsVertical() ? wm.IsVerticalLR() : wm.IsBidiLTR())) {
+      Direction direction = directions[index];
+      direction.mHorizontal *= -1;
+      return direction;
+    }
+  }
+
+  return directions[index];
+}
+
+void
+nsResizerFrame::MouseClicked(WidgetMouseEvent* aEvent)
+{
+  // Execute the oncommand event handler.
+  nsContentUtils::DispatchXULCommand(mContent, aEvent && aEvent->IsTrusted());
+}
diff --git a/layout/xul/nsResizerFrame.h b/layout/xul/nsResizerFrame.h
new file mode 100644
index 0000000000..92656bc764
--- /dev/null
+++ b/layout/xul/nsResizerFrame.h
@@ -0,0 +1,71 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsResizerFrame_h___
+#define nsResizerFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "mozilla/EventForwards.h"
+#include "nsTitleBarFrame.h"
+
+class nsIBaseWindow;
+
+class nsResizerFrame : public nsTitleBarFrame 
+{
+protected:
+  struct Direction {
+    int8_t mHorizontal;
+    int8_t mVertical;
+  };
+
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewResizerFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);  
+
+  explicit nsResizerFrame(nsStyleContext* aContext);
+
+  virtual nsresult HandleEvent(nsPresContext* aPresContext,
+                               mozilla::WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  virtual void MouseClicked(mozilla::WidgetMouseEvent* aEvent) override;
+
+protected:
+  nsIContent* GetContentToResize(nsIPresShell* aPresShell, nsIBaseWindow** aWindow);
+
+  Direction GetDirection();
+
+  /**
+   * Adjust the window position and size in a direction according to the mouse
+   * movement and the resizer direction. The minimum and maximum size is used
+   * to constrain the size.
+   *
+   * @param aPos left or top position
+   * @param aSize width or height
+   * @param aMinSize minimum width or height
+   * @param aMacSize maximum width or height
+   * @param aMovement the amount the mouse was moved
+   * @param aResizerDirection resizer direction returned by GetDirection
+   */
+  static void AdjustDimensions(int32_t* aPos, int32_t* aSize,
+                               int32_t aMinSize, int32_t aMaxSize,
+                               int32_t aMovement, int8_t aResizerDirection);
+
+  struct SizeInfo {
+    nsString width, height;
+  };
+  static void SizeInfoDtorFunc(void *aObject, nsIAtom *aPropertyName,
+                               void *aPropertyValue, void *aData);
+  static void ResizeContent(nsIContent* aContent, const Direction& aDirection,
+                            const SizeInfo& aSizeInfo, SizeInfo* aOriginalSizeInfo);
+  static void MaybePersistOriginalSize(nsIContent* aContent, const SizeInfo& aSizeInfo);
+  static void RestoreOriginalSize(nsIContent* aContent);
+
+protected:
+  LayoutDeviceIntRect mMouseDownRect;
+  LayoutDeviceIntPoint mMouseDownPoint;
+}; // class nsResizerFrame
+
+#endif /* nsResizerFrame_h___ */
diff --git a/layout/xul/nsRootBoxFrame.cpp b/layout/xul/nsRootBoxFrame.cpp
new file mode 100644
index 0000000000..fe41dce527
--- /dev/null
+++ b/layout/xul/nsRootBoxFrame.cpp
@@ -0,0 +1,291 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsHTMLParts.h"
+#include "nsStyleConsts.h"
+#include "nsGkAtoms.h"
+#include "nsIPresShell.h"
+#include "nsBoxFrame.h"
+#include "nsStackLayout.h"
+#include "nsIRootBox.h"
+#include "nsIContent.h"
+#include "nsXULTooltipListener.h"
+#include "nsFrameManager.h"
+#include "mozilla/BasicEvents.h"
+
+using namespace mozilla;
+
+// Interface IDs
+
+//#define DEBUG_REFLOW
+
+// static
+nsIRootBox*
+nsIRootBox::GetRootBox(nsIPresShell* aShell)
+{
+  if (!aShell) {
+    return nullptr;
+  }
+  nsIFrame* rootFrame = aShell->FrameManager()->GetRootFrame();
+  if (!rootFrame) {
+    return nullptr;
+  }
+
+  if (rootFrame) {
+    rootFrame = rootFrame->PrincipalChildList().FirstChild();
+  }
+
+  nsIRootBox* rootBox = do_QueryFrame(rootFrame);
+  return rootBox;
+}
+
+class nsRootBoxFrame : public nsBoxFrame, public nsIRootBox {
+public:
+
+  friend nsIFrame* NS_NewBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+  explicit nsRootBoxFrame(nsStyleContext* aContext);
+
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  virtual nsPopupSetFrame* GetPopupSetFrame() override;
+  virtual void SetPopupSetFrame(nsPopupSetFrame* aPopupSet) override;
+  virtual nsIContent* GetDefaultTooltip() override;
+  virtual void SetDefaultTooltip(nsIContent* aTooltip) override;
+  virtual nsresult AddTooltipSupport(nsIContent* aNode) override;
+  virtual nsresult RemoveTooltipSupport(nsIContent* aNode) override;
+
+  virtual void AppendFrames(ChildListID     aListID,
+                            nsFrameList&    aFrameList) override;
+  virtual void InsertFrames(ChildListID     aListID,
+                            nsIFrame*       aPrevFrame,
+                            nsFrameList&    aFrameList) override;
+  virtual void RemoveFrame(ChildListID     aListID,
+                           nsIFrame*       aOldFrame) override;
+
+  virtual void Reflow(nsPresContext*          aPresContext,
+                          ReflowOutput&     aDesiredSize,
+                          const ReflowInput& aReflowInput,
+                          nsReflowStatus&          aStatus) override;
+  virtual nsresult HandleEvent(nsPresContext* aPresContext,
+                               WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+
+  /**
+   * Get the "type" of the frame
+   *
+   * @see nsGkAtoms::rootFrame
+   */
+  virtual nsIAtom* GetType() const override;
+
+  virtual bool IsFrameOfType(uint32_t aFlags) const override
+  {
+    // Override bogus IsFrameOfType in nsBoxFrame.
+    if (aFlags & (nsIFrame::eReplacedContainsBlock | nsIFrame::eReplaced))
+      return false;
+    return nsBoxFrame::IsFrameOfType(aFlags);
+  }
+  
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override;
+#endif
+
+  nsPopupSetFrame* mPopupSetFrame;
+
+protected:
+  nsIContent* mDefaultTooltip;
+};
+
+//----------------------------------------------------------------------
+
+nsContainerFrame*
+NS_NewRootBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsRootBoxFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsRootBoxFrame)
+
+nsRootBoxFrame::nsRootBoxFrame(nsStyleContext* aContext):
+  nsBoxFrame(aContext, true)
+{
+  mPopupSetFrame = nullptr;
+
+  nsCOMPtr<nsBoxLayout> layout;
+  NS_NewStackLayout(layout);
+  SetXULLayoutManager(layout);
+}
+
+void
+nsRootBoxFrame::AppendFrames(ChildListID     aListID,
+                             nsFrameList&    aFrameList)
+{
+  MOZ_ASSERT(aListID == kPrincipalList, "unexpected child list ID");
+  MOZ_ASSERT(mFrames.IsEmpty(), "already have a child frame");
+  nsBoxFrame::AppendFrames(aListID, aFrameList);
+}
+
+void
+nsRootBoxFrame::InsertFrames(ChildListID     aListID,
+                             nsIFrame*       aPrevFrame,
+                             nsFrameList&    aFrameList)
+{
+  // Because we only support a single child frame inserting is the same
+  // as appending.
+  MOZ_ASSERT(!aPrevFrame, "unexpected previous sibling frame");
+  AppendFrames(aListID, aFrameList);
+}
+
+void
+nsRootBoxFrame::RemoveFrame(ChildListID     aListID,
+                            nsIFrame*       aOldFrame)
+{
+  NS_ASSERTION(aListID == kPrincipalList, "unexpected child list ID");
+  if (aOldFrame == mFrames.FirstChild()) {
+    nsBoxFrame::RemoveFrame(aListID, aOldFrame);
+  } else {
+    MOZ_CRASH("unknown aOldFrame");
+  }
+}
+
+#ifdef DEBUG_REFLOW
+int32_t gReflows = 0;
+#endif
+
+void
+nsRootBoxFrame::Reflow(nsPresContext*           aPresContext,
+                       ReflowOutput&     aDesiredSize,
+                       const ReflowInput& aReflowInput,
+                       nsReflowStatus&          aStatus)
+{
+  DO_GLOBAL_REFLOW_COUNT("nsRootBoxFrame");
+
+#ifdef DEBUG_REFLOW
+  gReflows++;
+  printf("----Reflow %d----\n", gReflows);
+#endif
+  return nsBoxFrame::Reflow(aPresContext, aDesiredSize, aReflowInput, aStatus);
+}
+
+void
+nsRootBoxFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                 const nsRect&           aDirtyRect,
+                                 const nsDisplayListSet& aLists)
+{
+  if (mContent && mContent->GetProperty(nsGkAtoms::DisplayPortMargins)) {
+    // The XUL document's root element may have displayport margins set in
+    // ChromeProcessController::InitializeRoot, and we should to supply the
+    // base rect.
+    nsRect displayPortBase = aDirtyRect.Intersect(nsRect(nsPoint(0, 0), GetSize()));
+    nsLayoutUtils::SetDisplayPortBase(mContent, displayPortBase);
+  }
+
+  // root boxes don't need a debug border/outline or a selection overlay...
+  // They *may* have a background propagated to them, so force creation
+  // of a background display list element.
+  DisplayBorderBackgroundOutline(aBuilder, aLists, true);
+
+  BuildDisplayListForChildren(aBuilder, aDirtyRect, aLists);
+}
+
+nsresult
+nsRootBoxFrame::HandleEvent(nsPresContext* aPresContext,
+                            WidgetGUIEvent* aEvent,
+                            nsEventStatus* aEventStatus)
+{
+  NS_ENSURE_ARG_POINTER(aEventStatus);
+  if (nsEventStatus_eConsumeNoDefault == *aEventStatus) {
+    return NS_OK;
+  }
+
+  if (aEvent->mMessage == eMouseUp) {
+    nsFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+  }
+
+  return NS_OK;
+}
+
+// REVIEW: The override here was doing nothing since nsBoxFrame is our
+// parent class
+nsIAtom*
+nsRootBoxFrame::GetType() const
+{
+  return nsGkAtoms::rootFrame;
+}
+
+nsPopupSetFrame*
+nsRootBoxFrame::GetPopupSetFrame()
+{
+  return mPopupSetFrame;
+}
+
+void
+nsRootBoxFrame::SetPopupSetFrame(nsPopupSetFrame* aPopupSet)
+{
+  // Under normal conditions this should only be called once.  However,
+  // if something triggers ReconstructDocElementHierarchy, we will
+  // destroy this frame's child (the nsDocElementBoxFrame), but not this
+  // frame.  This will cause the popupset to remove itself by calling
+  // |SetPopupSetFrame(nullptr)|, and then we'll be able to accept a new
+  // popupset.  Since the anonymous content is associated with the
+  // nsDocElementBoxFrame, we'll get a new popupset when the new doc
+  // element box frame is created.
+  if (!mPopupSetFrame || !aPopupSet) {
+    mPopupSetFrame = aPopupSet;
+  } else {
+    NS_NOTREACHED("Popup set is already defined! Only 1 allowed.");
+  }
+}
+
+nsIContent*
+nsRootBoxFrame::GetDefaultTooltip()
+{
+  return mDefaultTooltip;
+}
+
+void
+nsRootBoxFrame::SetDefaultTooltip(nsIContent* aTooltip)
+{
+  mDefaultTooltip = aTooltip;
+}
+
+nsresult
+nsRootBoxFrame::AddTooltipSupport(nsIContent* aNode)
+{
+  NS_ENSURE_TRUE(aNode, NS_ERROR_NULL_POINTER);
+
+  nsXULTooltipListener *listener = nsXULTooltipListener::GetInstance();
+  if (!listener)
+    return NS_ERROR_OUT_OF_MEMORY;
+
+  return listener->AddTooltipSupport(aNode);
+}
+
+nsresult
+nsRootBoxFrame::RemoveTooltipSupport(nsIContent* aNode)
+{
+  // XXjh yuck, I'll have to implement a way to get at
+  // the tooltip listener for a given node to make 
+  // this work.  Not crucial, we aren't removing 
+  // tooltips from any nodes in the app just yet.
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_QUERYFRAME_HEAD(nsRootBoxFrame)
+  NS_QUERYFRAME_ENTRY(nsIRootBox)
+NS_QUERYFRAME_TAIL_INHERITING(nsBoxFrame)
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+nsRootBoxFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("RootBox"), aResult);
+}
+#endif
diff --git a/layout/xul/nsScrollBoxFrame.cpp b/layout/xul/nsScrollBoxFrame.cpp
new file mode 100644
index 0000000000..4a6c9c2a8c
--- /dev/null
+++ b/layout/xul/nsScrollBoxFrame.cpp
@@ -0,0 +1,178 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMPtr.h"
+#include "nsPresContext.h"
+#include "nsGkAtoms.h"
+#include "nsButtonBoxFrame.h"
+#include "nsITimer.h"
+#include "nsRepeatService.h"
+#include "mozilla/MouseEvents.h"
+#include "nsIContent.h"
+
+using namespace mozilla;
+
+class nsAutoRepeatBoxFrame : public nsButtonBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewAutoRepeatBoxFrame(nsIPresShell* aPresShell,
+                                            nsStyleContext* aContext);
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+  virtual nsresult HandleEvent(nsPresContext* aPresContext,
+                               WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  NS_IMETHOD HandlePress(nsPresContext* aPresContext,
+                         WidgetGUIEvent* aEvent,
+                         nsEventStatus* aEventStatus) override;
+
+  NS_IMETHOD HandleRelease(nsPresContext* aPresContext,
+                           WidgetGUIEvent* aEvent,
+                           nsEventStatus* aEventStatus) override;
+
+protected:
+  explicit nsAutoRepeatBoxFrame(nsStyleContext* aContext):
+    nsButtonBoxFrame(aContext) {}
+  
+  void StartRepeat() {
+    if (IsActivatedOnHover()) {
+      // No initial delay on hover.
+      nsRepeatService::GetInstance()->Start(Notify, this, 0);
+    } else {
+      nsRepeatService::GetInstance()->Start(Notify, this);
+    }
+  }
+  void StopRepeat() {
+    nsRepeatService::GetInstance()->Stop(Notify, this);
+  }
+  void Notify();
+  static void Notify(void* aData) {
+    static_cast<nsAutoRepeatBoxFrame*>(aData)->Notify();
+  }
+
+  bool mTrustedEvent;
+  
+  bool IsActivatedOnHover();
+};
+
+nsIFrame*
+NS_NewAutoRepeatBoxFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsAutoRepeatBoxFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsAutoRepeatBoxFrame)
+
+nsresult
+nsAutoRepeatBoxFrame::HandleEvent(nsPresContext* aPresContext,
+                                  WidgetGUIEvent* aEvent,
+                                  nsEventStatus* aEventStatus)
+{  
+  NS_ENSURE_ARG_POINTER(aEventStatus);
+  if (nsEventStatus_eConsumeNoDefault == *aEventStatus) {
+    return NS_OK;
+  }
+
+  switch(aEvent->mMessage) {
+    // repeat mode may be "hover" for repeating while the mouse is hovering
+    // over the element, otherwise repetition is done while the element is
+    // active (pressed).
+    case eMouseEnterIntoWidget:
+    case eMouseOver:
+      if (IsActivatedOnHover()) {
+        StartRepeat();
+        mTrustedEvent = aEvent->IsTrusted();
+      }
+      break;
+
+    case eMouseExitFromWidget:
+    case eMouseOut:
+      // always stop on mouse exit
+      StopRepeat();
+      // Not really necessary but do this to be safe
+      mTrustedEvent = false;
+      break;
+
+    case eMouseClick: {
+      WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+      if (mouseEvent->IsLeftClickEvent()) {
+        // skip button frame handling to prevent click handling
+        return nsBoxFrame::HandleEvent(aPresContext, mouseEvent, aEventStatus);
+      }
+      break;
+    }
+
+    default:
+      break;
+  }
+     
+  return nsButtonBoxFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+}
+
+NS_IMETHODIMP
+nsAutoRepeatBoxFrame::HandlePress(nsPresContext* aPresContext,
+                                  WidgetGUIEvent* aEvent,
+                                  nsEventStatus* aEventStatus)
+{
+  if (!IsActivatedOnHover()) {
+    StartRepeat();
+    mTrustedEvent = aEvent->IsTrusted();
+    DoMouseClick(aEvent, mTrustedEvent);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsAutoRepeatBoxFrame::HandleRelease(nsPresContext* aPresContext,
+                                    WidgetGUIEvent* aEvent,
+                                    nsEventStatus* aEventStatus)
+{
+  if (!IsActivatedOnHover()) {
+    StopRepeat();
+  }
+  return NS_OK;
+}
+
+nsresult
+nsAutoRepeatBoxFrame::AttributeChanged(int32_t aNameSpaceID,
+                                       nsIAtom* aAttribute,
+                                       int32_t aModType)
+{
+  if (aAttribute == nsGkAtoms::type) {
+    StopRepeat();
+  }
+  return NS_OK;
+}
+
+void
+nsAutoRepeatBoxFrame::Notify()
+{
+  DoMouseClick(nullptr, mTrustedEvent);
+}
+
+void
+nsAutoRepeatBoxFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  // Ensure our repeat service isn't going... it's possible that a scrollbar can disappear out
+  // from under you while you're in the process of scrolling.
+  StopRepeat();
+  nsButtonBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+bool
+nsAutoRepeatBoxFrame::IsActivatedOnHover()
+{
+  return mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::repeat,
+                               nsGkAtoms::hover, eCaseMatters);
+}
diff --git a/layout/xul/nsScrollbarButtonFrame.cpp b/layout/xul/nsScrollbarButtonFrame.cpp
new file mode 100644
index 0000000000..206d9717f6
--- /dev/null
+++ b/layout/xul/nsScrollbarButtonFrame.cpp
@@ -0,0 +1,298 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsScrollbarButtonFrame.h"
+#include "nsPresContext.h"
+#include "nsIContent.h"
+#include "nsCOMPtr.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsSliderFrame.h"
+#include "nsScrollbarFrame.h"
+#include "nsIScrollbarMediator.h"
+#include "nsRepeatService.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/layers/ScrollInputMethods.h"
+
+using namespace mozilla;
+using mozilla::layers::ScrollInputMethod;
+
+//
+// NS_NewToolbarFrame
+//
+// Creates a new Toolbar frame and returns it
+//
+nsIFrame*
+NS_NewScrollbarButtonFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsScrollbarButtonFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsScrollbarButtonFrame)
+
+nsresult
+nsScrollbarButtonFrame::HandleEvent(nsPresContext* aPresContext,
+                                    WidgetGUIEvent* aEvent,
+                                    nsEventStatus* aEventStatus)
+{  
+  NS_ENSURE_ARG_POINTER(aEventStatus);
+
+  // If a web page calls event.preventDefault() we still want to
+  // scroll when scroll arrow is clicked. See bug 511075.
+  if (!mContent->IsInNativeAnonymousSubtree() &&
+      nsEventStatus_eConsumeNoDefault == *aEventStatus) {
+    return NS_OK;
+  }
+
+  switch (aEvent->mMessage) {
+    case eMouseDown:
+      mCursorOnThis = true;
+      // if we didn't handle the press ourselves, pass it on to the superclass
+      if (HandleButtonPress(aPresContext, aEvent, aEventStatus)) {
+        return NS_OK;
+      }
+      break;
+    case eMouseUp:
+      HandleRelease(aPresContext, aEvent, aEventStatus);
+      break;
+    case eMouseOut:
+      mCursorOnThis = false;
+      break;
+    case eMouseMove: {
+      nsPoint cursor =
+        nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, this);
+      nsRect frameRect(nsPoint(0, 0), GetSize());
+      mCursorOnThis = frameRect.Contains(cursor);
+      break;
+    }
+    default:
+      break;
+  }
+
+  return nsButtonBoxFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+}
+
+bool
+nsScrollbarButtonFrame::HandleButtonPress(nsPresContext* aPresContext,
+                                          WidgetGUIEvent* aEvent,
+                                          nsEventStatus* aEventStatus)
+{
+  // Get the desired action for the scrollbar button.
+  LookAndFeel::IntID tmpAction;
+  uint16_t button = aEvent->AsMouseEvent()->button;
+  if (button == WidgetMouseEvent::eLeftButton) {
+    tmpAction = LookAndFeel::eIntID_ScrollButtonLeftMouseButtonAction;
+  } else if (button == WidgetMouseEvent::eMiddleButton) {
+    tmpAction = LookAndFeel::eIntID_ScrollButtonMiddleMouseButtonAction;
+  } else if (button == WidgetMouseEvent::eRightButton) {
+    tmpAction = LookAndFeel::eIntID_ScrollButtonRightMouseButtonAction;
+  } else {
+    return false;
+  }
+
+  // Get the button action metric from the pres. shell.
+  int32_t pressedButtonAction;
+  if (NS_FAILED(LookAndFeel::GetInt(tmpAction, &pressedButtonAction))) {
+    return false;
+  }
+
+  // get the scrollbar control
+  nsIFrame* scrollbar;
+  GetParentWithTag(nsGkAtoms::scrollbar, this, scrollbar);
+
+  if (scrollbar == nullptr)
+    return false;
+ 
+  static nsIContent::AttrValuesArray strings[] = { &nsGkAtoms::increment,
+                                                   &nsGkAtoms::decrement,
+                                                   nullptr };
+  int32_t index = mContent->FindAttrValueIn(kNameSpaceID_None,
+                                            nsGkAtoms::type,
+                                            strings, eCaseMatters);
+  int32_t direction;
+  if (index == 0)
+    direction = 1;
+  else if (index == 1)
+    direction = -1;
+  else
+    return false;
+
+  bool repeat = pressedButtonAction != 2;
+  // set this attribute so we can style it later
+  nsWeakFrame weakFrame(this);
+  mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::active, NS_LITERAL_STRING("true"), true);
+
+  nsIPresShell::SetCapturingContent(mContent, CAPTURE_IGNOREALLOWED);
+
+  if (!weakFrame.IsAlive()) {
+    return false;
+  }
+
+  nsScrollbarFrame* sb = do_QueryFrame(scrollbar);
+  if (sb) {
+    nsIScrollbarMediator* m = sb->GetScrollbarMediator();
+    switch (pressedButtonAction) {
+    case 0:
+      sb->SetIncrementToLine(direction);
+      if (m) {
+        m->ScrollByLine(sb, direction, nsIScrollbarMediator::ENABLE_SNAP);
+      }
+      break;
+    case 1:
+      sb->SetIncrementToPage(direction);
+      if (m) {
+        m->ScrollByPage(sb, direction, nsIScrollbarMediator::ENABLE_SNAP);
+      }
+      break;
+    case 2:
+      sb->SetIncrementToWhole(direction);
+      if (m) {
+        m->ScrollByWhole(sb, direction, nsIScrollbarMediator::ENABLE_SNAP);
+      }
+      break;
+    case 3:
+    default:
+      // We were told to ignore this click, or someone assigned a non-standard
+      // value to the button's action.
+      return false;
+    }
+    if (!weakFrame.IsAlive()) {
+      return false;
+    }
+
+    mozilla::Telemetry::Accumulate(mozilla::Telemetry::SCROLL_INPUT_METHODS,
+        (uint32_t) ScrollInputMethod::MainThreadScrollbarButtonClick);
+
+    if (!m) {
+      sb->MoveToNewPosition();
+      if (!weakFrame.IsAlive()) {
+        return false;
+      }
+    }
+  }
+  if (repeat) {
+    StartRepeat();
+  }
+  return true;
+}
+
+NS_IMETHODIMP 
+nsScrollbarButtonFrame::HandleRelease(nsPresContext* aPresContext,
+                                      WidgetGUIEvent* aEvent,
+                                      nsEventStatus* aEventStatus)
+{
+  nsIPresShell::SetCapturingContent(nullptr, 0);
+  // we're not active anymore
+  mContent->UnsetAttr(kNameSpaceID_None, nsGkAtoms::active, true);
+  StopRepeat();
+  nsIFrame* scrollbar;
+  GetParentWithTag(nsGkAtoms::scrollbar, this, scrollbar);
+  nsScrollbarFrame* sb = do_QueryFrame(scrollbar);
+  if (sb) {
+    nsIScrollbarMediator* m = sb->GetScrollbarMediator();
+    if (m) {
+      m->ScrollbarReleased(sb);
+    }
+  }
+  return NS_OK;
+}
+
+void nsScrollbarButtonFrame::Notify()
+{
+  if (mCursorOnThis ||
+      LookAndFeel::GetInt(
+        LookAndFeel::eIntID_ScrollbarButtonAutoRepeatBehavior, 0)) {
+    // get the scrollbar control
+    nsIFrame* scrollbar;
+    GetParentWithTag(nsGkAtoms::scrollbar, this, scrollbar);
+    nsScrollbarFrame* sb = do_QueryFrame(scrollbar);
+    if (sb) {
+      nsIScrollbarMediator* m = sb->GetScrollbarMediator();
+      if (m) {
+        m->RepeatButtonScroll(sb);
+      } else {
+        sb->MoveToNewPosition();
+      }
+    }
+  }
+}
+
+void
+nsScrollbarButtonFrame::MouseClicked(WidgetGUIEvent* aEvent)
+{
+  nsButtonBoxFrame::MouseClicked(aEvent);
+  //MouseClicked();
+}
+
+nsresult
+nsScrollbarButtonFrame::GetChildWithTag(nsIAtom* atom, nsIFrame* start,
+                                        nsIFrame*& result)
+{
+  // recursively search our children
+  for (nsIFrame* childFrame : start->PrincipalChildList())
+  {
+    // get the content node
+    nsIContent* child = childFrame->GetContent();
+
+    if (child) {
+      // see if it is the child
+       if (child->IsXULElement(atom))
+       {
+         result = childFrame;
+
+         return NS_OK;
+       }
+    }
+
+     // recursive search the child
+     GetChildWithTag(atom, childFrame, result);
+     if (result != nullptr) 
+       return NS_OK;
+  }
+
+  result = nullptr;
+  return NS_OK;
+}
+
+nsresult
+nsScrollbarButtonFrame::GetParentWithTag(nsIAtom* toFind, nsIFrame* start,
+                                         nsIFrame*& result)
+{
+   while (start)
+   {
+      start = start->GetParent();
+
+      if (start) {
+        // get the content node
+        nsIContent* child = start->GetContent();
+
+        if (child && child->IsXULElement(toFind)) {
+          result = start;
+          return NS_OK;
+        }
+      }
+   }
+
+   result = nullptr;
+   return NS_OK;
+}
+
+void
+nsScrollbarButtonFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  // Ensure our repeat service isn't going... it's possible that a scrollbar can disappear out
+  // from under you while you're in the process of scrolling.
+  StopRepeat();
+  nsButtonBoxFrame::DestroyFrom(aDestructRoot);
+}
diff --git a/layout/xul/nsScrollbarButtonFrame.h b/layout/xul/nsScrollbarButtonFrame.h
new file mode 100644
index 0000000000..9be73b13c6
--- /dev/null
+++ b/layout/xul/nsScrollbarButtonFrame.h
@@ -0,0 +1,81 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+
+  Eric D Vaughan
+  This class lays out its children either vertically or horizontally
+ 
+**/
+
+#ifndef nsScrollbarButtonFrame_h___
+#define nsScrollbarButtonFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsButtonBoxFrame.h"
+#include "nsITimer.h"
+#include "nsRepeatService.h"
+
+class nsScrollbarButtonFrame : public nsButtonBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  explicit nsScrollbarButtonFrame(nsStyleContext* aContext):
+    nsButtonBoxFrame(aContext), mCursorOnThis(false) {}
+
+  // Overrides
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  friend nsIFrame* NS_NewScrollbarButtonFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+  virtual nsresult HandleEvent(nsPresContext* aPresContext,
+                               mozilla::WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  static nsresult GetChildWithTag(nsIAtom* atom, nsIFrame* start, nsIFrame*& result);
+  static nsresult GetParentWithTag(nsIAtom* atom, nsIFrame* start, nsIFrame*& result);
+
+  bool HandleButtonPress(nsPresContext* aPresContext,
+                         mozilla::WidgetGUIEvent* aEvent,
+                         nsEventStatus* aEventStatus);
+
+  NS_IMETHOD HandleMultiplePress(nsPresContext* aPresContext,
+                                 mozilla::WidgetGUIEvent* aEvent,
+                                 nsEventStatus* aEventStatus,
+                                 bool aControlHeld) override
+ {
+   return NS_OK;
+ }
+
+  NS_IMETHOD HandleDrag(nsPresContext* aPresContext,
+                        mozilla::WidgetGUIEvent* aEvent,
+                        nsEventStatus* aEventStatus) override
+  {
+    return NS_OK;
+  }
+
+  NS_IMETHOD HandleRelease(nsPresContext* aPresContext,
+                           mozilla::WidgetGUIEvent* aEvent,
+                           nsEventStatus* aEventStatus) override;
+
+protected:
+  virtual void MouseClicked(mozilla::WidgetGUIEvent* aEvent) override;
+
+  void StartRepeat() {
+    nsRepeatService::GetInstance()->Start(Notify, this);
+  }
+  void StopRepeat() {
+    nsRepeatService::GetInstance()->Stop(Notify, this);
+  }
+  void Notify();
+  static void Notify(void* aData) {
+    static_cast<nsScrollbarButtonFrame*>(aData)->Notify();
+  }
+  
+  bool mCursorOnThis;
+};
+
+#endif
diff --git a/layout/xul/nsScrollbarFrame.cpp b/layout/xul/nsScrollbarFrame.cpp
new file mode 100644
index 0000000000..d9c28a2bf9
--- /dev/null
+++ b/layout/xul/nsScrollbarFrame.cpp
@@ -0,0 +1,311 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsScrollbarFrame.h"
+#include "nsSliderFrame.h"
+#include "nsScrollbarButtonFrame.h"
+#include "nsGkAtoms.h"
+#include "nsIScrollableFrame.h"
+#include "nsIScrollbarMediator.h"
+#include "mozilla/LookAndFeel.h"
+#include "nsThemeConstants.h"
+#include "nsIContent.h"
+#include "nsIDOMMutationEvent.h"
+
+using namespace mozilla;
+
+//
+// NS_NewScrollbarFrame
+//
+// Creates a new scrollbar frame and returns it
+//
+nsIFrame*
+NS_NewScrollbarFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsScrollbarFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsScrollbarFrame)
+
+NS_QUERYFRAME_HEAD(nsScrollbarFrame)
+  NS_QUERYFRAME_ENTRY(nsScrollbarFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsBoxFrame)
+
+void
+nsScrollbarFrame::Init(nsIContent*       aContent,
+                       nsContainerFrame* aParent,
+                       nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  // We want to be a reflow root since we use reflows to move the
+  // slider.  Any reflow inside the scrollbar frame will be a reflow to
+  // move the slider and will thus not change anything outside of the
+  // scrollbar or change the size of the scrollbar frame.
+  mState |= NS_FRAME_REFLOW_ROOT;
+}
+
+void
+nsScrollbarFrame::Reflow(nsPresContext*          aPresContext,
+                         ReflowOutput&     aDesiredSize,
+                         const ReflowInput& aReflowInput,
+                         nsReflowStatus&          aStatus)
+{
+  nsBoxFrame::Reflow(aPresContext, aDesiredSize, aReflowInput, aStatus);
+
+  // nsGfxScrollFrame may have told us to shrink to nothing. If so, make sure our
+  // desired size agrees.
+  if (aReflowInput.AvailableWidth() == 0) {
+    aDesiredSize.Width() = 0;
+  }
+  if (aReflowInput.AvailableHeight() == 0) {
+    aDesiredSize.Height() = 0;
+  }
+}
+
+nsIAtom*
+nsScrollbarFrame::GetType() const
+{
+  return nsGkAtoms::scrollbarFrame;
+}
+
+nsresult
+nsScrollbarFrame::AttributeChanged(int32_t aNameSpaceID,
+                                   nsIAtom* aAttribute,
+                                   int32_t aModType)
+{
+  nsresult rv = nsBoxFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                             aModType);
+
+  // if the current position changes, notify any nsGfxScrollFrame
+  // parent we may have
+  if (aAttribute != nsGkAtoms::curpos)
+    return rv;
+
+  nsIScrollableFrame* scrollable = do_QueryFrame(GetParent());
+  if (!scrollable)
+    return rv;
+
+  nsCOMPtr<nsIContent> content(mContent);
+  scrollable->CurPosAttributeChanged(content);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsScrollbarFrame::HandlePress(nsPresContext* aPresContext,
+                              WidgetGUIEvent* aEvent,
+                              nsEventStatus* aEventStatus)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsScrollbarFrame::HandleMultiplePress(nsPresContext* aPresContext,
+                                      WidgetGUIEvent* aEvent,
+                                      nsEventStatus* aEventStatus,
+                                      bool aControlHeld)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsScrollbarFrame::HandleDrag(nsPresContext* aPresContext,
+                             WidgetGUIEvent* aEvent,
+                             nsEventStatus* aEventStatus)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsScrollbarFrame::HandleRelease(nsPresContext* aPresContext,
+                                WidgetGUIEvent* aEvent,
+                                nsEventStatus* aEventStatus)
+{
+  return NS_OK;
+}
+
+void
+nsScrollbarFrame::SetScrollbarMediatorContent(nsIContent* aMediator)
+{
+  mScrollbarMediator = aMediator;
+}
+
+nsIScrollbarMediator*
+nsScrollbarFrame::GetScrollbarMediator()
+{
+  if (!mScrollbarMediator) {
+    return nullptr;
+  }
+  nsIFrame* f = mScrollbarMediator->GetPrimaryFrame();
+  nsIScrollableFrame* scrollFrame = do_QueryFrame(f);
+  nsIScrollbarMediator* sbm;
+
+  if (scrollFrame) {
+    nsIFrame* scrolledFrame = scrollFrame->GetScrolledFrame();
+    sbm = do_QueryFrame(scrolledFrame);
+    if (sbm) {
+      return sbm;
+    }
+  }
+  sbm = do_QueryFrame(f);
+  if (f && !sbm) {
+    f = f->PresContext()->PresShell()->GetRootScrollFrame();
+    if (f && f->GetContent() == mScrollbarMediator) {
+      return do_QueryFrame(f);
+    }
+  }
+  return sbm;
+}
+
+nsresult
+nsScrollbarFrame::GetXULMargin(nsMargin& aMargin)
+{
+  nsresult rv = NS_ERROR_FAILURE;
+  aMargin.SizeTo(0,0,0,0);
+
+  if (LookAndFeel::GetInt(LookAndFeel::eIntID_UseOverlayScrollbars) != 0) {
+    nsPresContext* presContext = PresContext();
+    nsITheme* theme = presContext->GetTheme();
+    if (theme) {
+      LayoutDeviceIntSize size;
+      bool isOverridable;
+      theme->GetMinimumWidgetSize(presContext, this, NS_THEME_SCROLLBAR, &size,
+                                  &isOverridable);
+      if (IsXULHorizontal()) {
+        aMargin.top = -presContext->DevPixelsToAppUnits(size.height);
+      }
+      else {
+        aMargin.left = -presContext->DevPixelsToAppUnits(size.width);
+      }
+      rv = NS_OK;
+    }
+  }
+
+  if (NS_FAILED(rv)) {
+    rv = nsBox::GetXULMargin(aMargin);
+  }
+
+  if (NS_SUCCEEDED(rv) && !IsXULHorizontal()) {
+    nsIScrollbarMediator* scrollFrame = GetScrollbarMediator();
+    if (scrollFrame && !scrollFrame->IsScrollbarOnRight()) {
+      Swap(aMargin.left, aMargin.right);
+    }
+  }
+
+  return rv;
+}
+
+void
+nsScrollbarFrame::SetIncrementToLine(int32_t aDirection)
+{
+  // get the scrollbar's content node
+  nsIContent* content = GetContent();
+  mSmoothScroll = true;
+  mIncrement = aDirection * nsSliderFrame::GetIncrement(content);
+}
+
+void
+nsScrollbarFrame::SetIncrementToPage(int32_t aDirection)
+{
+  // get the scrollbar's content node
+  nsIContent* content = GetContent();
+  mSmoothScroll = true;
+  mIncrement = aDirection * nsSliderFrame::GetPageIncrement(content);
+}
+
+void
+nsScrollbarFrame::SetIncrementToWhole(int32_t aDirection)
+{
+  // get the scrollbar's content node
+  nsIContent* content = GetContent();
+  if (aDirection == -1)
+    mIncrement = -nsSliderFrame::GetCurrentPosition(content);
+  else
+    mIncrement = nsSliderFrame::GetMaxPosition(content) -
+                 nsSliderFrame::GetCurrentPosition(content);
+  // Don't repeat or use smooth scrolling if scrolling to beginning or end
+  // of a page.
+  mSmoothScroll = false;
+}
+
+int32_t
+nsScrollbarFrame::MoveToNewPosition()
+{
+  // get the scrollbar's content node
+  nsCOMPtr<nsIContent> content = GetContent();
+
+  // get the current pos
+  int32_t curpos = nsSliderFrame::GetCurrentPosition(content);
+
+  // get the max pos
+  int32_t maxpos = nsSliderFrame::GetMaxPosition(content);
+
+  // save the old curpos
+  int32_t oldCurpos = curpos;
+
+  // increment the given amount
+  if (mIncrement) {
+    curpos += mIncrement;
+  }
+
+  // make sure the current position is between the current and max positions
+  if (curpos < 0) {
+    curpos = 0;
+  } else if (curpos > maxpos) {
+    curpos = maxpos;
+  }
+
+  // set the current position of the slider.
+  nsAutoString curposStr;
+  curposStr.AppendInt(curpos);
+
+  nsWeakFrame weakFrame(this);
+  if (mSmoothScroll) {
+    content->SetAttr(kNameSpaceID_None, nsGkAtoms::smooth, NS_LITERAL_STRING("true"), false);
+  }
+  content->SetAttr(kNameSpaceID_None, nsGkAtoms::curpos, curposStr, false);
+  // notify the nsScrollbarFrame of the change
+  AttributeChanged(kNameSpaceID_None, nsGkAtoms::curpos, nsIDOMMutationEvent::MODIFICATION);
+  if (!weakFrame.IsAlive()) {
+    return curpos;
+  }
+  // notify all nsSliderFrames of the change
+  nsIFrame::ChildListIterator childLists(this);
+  for (; !childLists.IsDone(); childLists.Next()) {
+    nsFrameList::Enumerator childFrames(childLists.CurrentList());
+    for (; !childFrames.AtEnd(); childFrames.Next()) {
+      nsIFrame* f = childFrames.get();
+      nsSliderFrame* sliderFrame = do_QueryFrame(f);
+      if (sliderFrame) {
+        sliderFrame->AttributeChanged(kNameSpaceID_None, nsGkAtoms::curpos, nsIDOMMutationEvent::MODIFICATION);
+        if (!weakFrame.IsAlive()) {
+          return curpos;
+        }
+      }
+    }
+  }
+  // See if we have appearance information for a theme.
+  const nsStyleDisplay* disp = StyleDisplay();
+  nsPresContext* presContext = PresContext();
+  if (disp->mAppearance) {
+    nsITheme *theme = presContext->GetTheme();
+    if (theme && theme->ThemeSupportsWidget(presContext, this, disp->mAppearance)) {
+      bool repaint;
+      nsAttrValue oldValue;
+      oldValue.SetTo(oldCurpos);
+      theme->WidgetStateChanged(this, disp->mAppearance, nsGkAtoms::curpos,
+          &repaint, &oldValue);
+    }
+  }
+  content->UnsetAttr(kNameSpaceID_None, nsGkAtoms::smooth, false);
+  return curpos;
+}
diff --git a/layout/xul/nsScrollbarFrame.h b/layout/xul/nsScrollbarFrame.h
new file mode 100644
index 0000000000..4048bc05bc
--- /dev/null
+++ b/layout/xul/nsScrollbarFrame.h
@@ -0,0 +1,110 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// nsScrollbarFrame
+//
+
+#ifndef nsScrollbarFrame_h__
+#define nsScrollbarFrame_h__
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+class nsIScrollbarMediator;
+
+nsIFrame* NS_NewScrollbarFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+class nsScrollbarFrame : public nsBoxFrame
+{
+public:
+    explicit nsScrollbarFrame(nsStyleContext* aContext):
+      nsBoxFrame(aContext), mScrollbarMediator(nullptr) {}
+
+  NS_DECL_QUERYFRAME_TARGET(nsScrollbarFrame)
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override {
+    return MakeFrameName(NS_LITERAL_STRING("ScrollbarFrame"), aResult);
+  }
+#endif
+
+  // nsIFrame overrides
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  NS_IMETHOD HandlePress(nsPresContext* aPresContext,
+                         mozilla::WidgetGUIEvent* aEvent,
+                         nsEventStatus* aEventStatus) override;
+
+  NS_IMETHOD HandleMultiplePress(nsPresContext* aPresContext,
+                                 mozilla::WidgetGUIEvent* aEvent,
+                                 nsEventStatus* aEventStatus,
+                                 bool aControlHeld) override;
+
+  NS_IMETHOD HandleDrag(nsPresContext* aPresContext,
+                        mozilla::WidgetGUIEvent* aEvent,
+                        nsEventStatus* aEventStatus) override;
+
+  NS_IMETHOD HandleRelease(nsPresContext* aPresContext,
+                           mozilla::WidgetGUIEvent* aEvent,
+                           nsEventStatus* aEventStatus) override;
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual void Reflow(nsPresContext*           aPresContext,
+                      ReflowOutput&     aDesiredSize,
+                      const ReflowInput& aReflowInput,
+                      nsReflowStatus&          aStatus) override;
+
+  virtual nsIAtom* GetType() const override;  
+
+  void SetScrollbarMediatorContent(nsIContent* aMediator);
+  nsIScrollbarMediator* GetScrollbarMediator();
+
+  // nsBox methods
+
+  /**
+   * Treat scrollbars as clipping their children; overflowing children
+   * will not be allowed to set an overflow rect on this
+   * frame. This means that when the scroll code decides to hide a
+   * scrollframe by setting its height or width to zero, that will
+   * hide the children too.
+   */
+  virtual bool DoesClipChildren() override { return true; }
+
+  virtual nsresult GetXULMargin(nsMargin& aMargin) override;
+
+  /**
+   * The following three methods set the value of mIncrement when a
+   * scrollbar button is pressed.
+   */
+  void SetIncrementToLine(int32_t aDirection);
+  void SetIncrementToPage(int32_t aDirection);
+  void SetIncrementToWhole(int32_t aDirection);
+  /**
+   * MoveToNewPosition() adds mIncrement to the current position and
+   * updates the curpos attribute.
+   * @returns The new position after clamping, in CSS Pixels
+   * @note This method might destroy the frame, pres shell, and other objects.
+   */
+  int32_t MoveToNewPosition();
+  int32_t GetIncrement() { return mIncrement; }
+
+protected:
+  int32_t mIncrement; // Amount to scroll, in CSSPixels
+  bool mSmoothScroll;
+
+private:
+  nsCOMPtr<nsIContent> mScrollbarMediator;
+}; // class nsScrollbarFrame
+
+#endif
diff --git a/layout/xul/nsSliderFrame.cpp b/layout/xul/nsSliderFrame.cpp
new file mode 100644
index 0000000000..8e083f20ca
--- /dev/null
+++ b/layout/xul/nsSliderFrame.cpp
@@ -0,0 +1,1446 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsSliderFrame.h"
+
+#include "gfxPrefs.h"
+#include "nsStyleContext.h"
+#include "nsPresContext.h"
+#include "nsIContent.h"
+#include "nsCOMPtr.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsHTMLParts.h"
+#include "nsIPresShell.h"
+#include "nsCSSRendering.h"
+#include "nsIDOMEvent.h"
+#include "nsIDOMMouseEvent.h"
+#include "nsScrollbarButtonFrame.h"
+#include "nsISliderListener.h"
+#include "nsIScrollableFrame.h"
+#include "nsIScrollbarMediator.h"
+#include "nsISupportsImpl.h"
+#include "nsScrollbarFrame.h"
+#include "nsRepeatService.h"
+#include "nsBoxLayoutState.h"
+#include "nsSprocketLayout.h"
+#include "nsIServiceManager.h"
+#include "nsContentUtils.h"
+#include "nsLayoutUtils.h"
+#include "nsDisplayList.h"
+#include "mozilla/Assertions.h"         // for MOZ_ASSERT
+#include "mozilla/Preferences.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/layers/APZCCallbackHelper.h"
+#include "mozilla/layers/AsyncDragMetrics.h"
+#include "mozilla/layers/InputAPZContext.h"
+#include "mozilla/layers/ScrollInputMethods.h"
+#include <algorithm>
+
+using namespace mozilla;
+using mozilla::layers::APZCCallbackHelper;
+using mozilla::layers::AsyncDragMetrics;
+using mozilla::layers::InputAPZContext;
+using mozilla::layers::ScrollInputMethod;
+
+bool nsSliderFrame::gMiddlePref = false;
+int32_t nsSliderFrame::gSnapMultiplier;
+
+// Turn this on if you want to debug slider frames.
+#undef DEBUG_SLIDER
+
+static already_AddRefed<nsIContent>
+GetContentOfBox(nsIFrame *aBox)
+{
+  nsCOMPtr<nsIContent> content = aBox->GetContent();
+  return content.forget();
+}
+
+nsIFrame*
+NS_NewSliderFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsSliderFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsSliderFrame)
+
+NS_QUERYFRAME_HEAD(nsSliderFrame)
+  NS_QUERYFRAME_ENTRY(nsSliderFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsBoxFrame)
+
+nsSliderFrame::nsSliderFrame(nsStyleContext* aContext):
+  nsBoxFrame(aContext),
+  mCurPos(0),
+  mChange(0),
+  mDragFinished(true),
+  mUserChanged(false),
+  mScrollingWithAPZ(false),
+  mSuppressionActive(false)
+{
+}
+
+// stop timer
+nsSliderFrame::~nsSliderFrame()
+{
+  if (mSuppressionActive) {
+    APZCCallbackHelper::SuppressDisplayport(false, PresContext() ?
+                                                   PresContext()->PresShell() :
+                                                   nullptr);
+  }
+}
+
+void
+nsSliderFrame::Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  static bool gotPrefs = false;
+  if (!gotPrefs) {
+    gotPrefs = true;
+
+    gMiddlePref = Preferences::GetBool("middlemouse.scrollbarPosition");
+    gSnapMultiplier = Preferences::GetInt("slider.snapMultiplier");
+  }
+
+  mCurPos = GetCurrentPosition(aContent);
+}
+
+void
+nsSliderFrame::RemoveFrame(ChildListID     aListID,
+                           nsIFrame*       aOldFrame)
+{
+  nsBoxFrame::RemoveFrame(aListID, aOldFrame);
+  if (mFrames.IsEmpty())
+    RemoveListener();
+}
+
+void
+nsSliderFrame::InsertFrames(ChildListID     aListID,
+                            nsIFrame*       aPrevFrame,
+                            nsFrameList&    aFrameList)
+{
+  bool wasEmpty = mFrames.IsEmpty();
+  nsBoxFrame::InsertFrames(aListID, aPrevFrame, aFrameList);
+  if (wasEmpty)
+    AddListener();
+}
+
+void
+nsSliderFrame::AppendFrames(ChildListID     aListID,
+                            nsFrameList&    aFrameList)
+{
+  // if we have no children and on was added then make sure we add the
+  // listener
+  bool wasEmpty = mFrames.IsEmpty();
+  nsBoxFrame::AppendFrames(aListID, aFrameList);
+  if (wasEmpty)
+    AddListener();
+}
+
+int32_t
+nsSliderFrame::GetCurrentPosition(nsIContent* content)
+{
+  return GetIntegerAttribute(content, nsGkAtoms::curpos, 0);
+}
+
+int32_t
+nsSliderFrame::GetMinPosition(nsIContent* content)
+{
+  return GetIntegerAttribute(content, nsGkAtoms::minpos, 0);
+}
+
+int32_t
+nsSliderFrame::GetMaxPosition(nsIContent* content)
+{
+  return GetIntegerAttribute(content, nsGkAtoms::maxpos, 100);
+}
+
+int32_t
+nsSliderFrame::GetIncrement(nsIContent* content)
+{
+  return GetIntegerAttribute(content, nsGkAtoms::increment, 1);
+}
+
+
+int32_t
+nsSliderFrame::GetPageIncrement(nsIContent* content)
+{
+  return GetIntegerAttribute(content, nsGkAtoms::pageincrement, 10);
+}
+
+int32_t
+nsSliderFrame::GetIntegerAttribute(nsIContent* content, nsIAtom* atom, int32_t defaultValue)
+{
+    nsAutoString value;
+    content->GetAttr(kNameSpaceID_None, atom, value);
+    if (!value.IsEmpty()) {
+      nsresult error;
+
+      // convert it to an integer
+      defaultValue = value.ToInteger(&error);
+    }
+
+    return defaultValue;
+}
+
+class nsValueChangedRunnable : public Runnable
+{
+public:
+  nsValueChangedRunnable(nsISliderListener* aListener,
+                         nsIAtom* aWhich,
+                         int32_t aValue,
+                         bool aUserChanged)
+  : mListener(aListener), mWhich(aWhich),
+    mValue(aValue), mUserChanged(aUserChanged)
+  {}
+
+  NS_IMETHOD Run() override
+  {
+    return mListener->ValueChanged(nsDependentAtomString(mWhich),
+                                   mValue, mUserChanged);
+  }
+
+  nsCOMPtr<nsISliderListener> mListener;
+  nsCOMPtr<nsIAtom> mWhich;
+  int32_t mValue;
+  bool mUserChanged;
+};
+
+class nsDragStateChangedRunnable : public Runnable
+{
+public:
+  nsDragStateChangedRunnable(nsISliderListener* aListener,
+                             bool aDragBeginning)
+  : mListener(aListener),
+    mDragBeginning(aDragBeginning)
+  {}
+
+  NS_IMETHOD Run() override
+  {
+    return mListener->DragStateChanged(mDragBeginning);
+  }
+
+  nsCOMPtr<nsISliderListener> mListener;
+  bool mDragBeginning;
+};
+
+nsresult
+nsSliderFrame::AttributeChanged(int32_t aNameSpaceID,
+                                nsIAtom* aAttribute,
+                                int32_t aModType)
+{
+  nsresult rv = nsBoxFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                             aModType);
+  // if the current position changes
+  if (aAttribute == nsGkAtoms::curpos) {
+     CurrentPositionChanged();
+  } else if (aAttribute == nsGkAtoms::minpos ||
+             aAttribute == nsGkAtoms::maxpos) {
+      // bounds check it.
+
+      nsIFrame* scrollbarBox = GetScrollbar();
+      nsCOMPtr<nsIContent> scrollbar;
+      scrollbar = GetContentOfBox(scrollbarBox);
+      int32_t current = GetCurrentPosition(scrollbar);
+      int32_t min = GetMinPosition(scrollbar);
+      int32_t max = GetMaxPosition(scrollbar);
+
+      // inform the parent <scale> that the minimum or maximum changed
+      nsIFrame* parent = GetParent();
+      if (parent) {
+        nsCOMPtr<nsISliderListener> sliderListener = do_QueryInterface(parent->GetContent());
+        if (sliderListener) {
+          nsContentUtils::AddScriptRunner(
+            new nsValueChangedRunnable(sliderListener, aAttribute,
+                                       aAttribute == nsGkAtoms::minpos ? min : max, false));
+        }
+      }
+
+      if (current < min || current > max)
+      {
+        int32_t direction = 0;
+        if (current < min || max < min) {
+          current = min;
+          direction = -1;
+        } else if (current > max) {
+          current = max;
+          direction = 1;
+        }
+
+        // set the new position and notify observers
+        nsScrollbarFrame* scrollbarFrame = do_QueryFrame(scrollbarBox);
+        if (scrollbarFrame) {
+          nsIScrollbarMediator* mediator = scrollbarFrame->GetScrollbarMediator();
+          scrollbarFrame->SetIncrementToWhole(direction);
+          if (mediator) {
+            mediator->ScrollByWhole(scrollbarFrame, direction,
+                                    nsIScrollbarMediator::ENABLE_SNAP);
+          }
+        }
+        // 'this' might be destroyed here
+
+        nsContentUtils::AddScriptRunner(
+          new nsSetAttrRunnable(scrollbar, nsGkAtoms::curpos, current));
+      }
+  }
+
+  if (aAttribute == nsGkAtoms::minpos ||
+      aAttribute == nsGkAtoms::maxpos ||
+      aAttribute == nsGkAtoms::pageincrement ||
+      aAttribute == nsGkAtoms::increment) {
+
+      PresContext()->PresShell()->
+        FrameNeedsReflow(this, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
+  }
+
+  return rv;
+}
+
+void
+nsSliderFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists)
+{
+  if (aBuilder->IsForEventDelivery() && isDraggingThumb()) {
+    // This is EVIL, we shouldn't be messing with event delivery just to get
+    // thumb mouse drag events to arrive at the slider!
+    aLists.Outlines()->AppendNewToTop(new (aBuilder)
+      nsDisplayEventReceiver(aBuilder, this));
+    return;
+  }
+  
+  nsBoxFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);
+}
+
+void
+nsSliderFrame::BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists)
+{
+  // if we are too small to have a thumb don't paint it.
+  nsIFrame* thumb = nsBox::GetChildXULBox(this);
+
+  if (thumb) {
+    nsRect thumbRect(thumb->GetRect());
+    nsMargin m;
+    thumb->GetXULMargin(m);
+    thumbRect.Inflate(m);
+
+    nsRect crect;
+    GetXULClientRect(crect);
+
+    if (crect.width < thumbRect.width || crect.height < thumbRect.height)
+      return;
+
+    // If this scrollbar is the scrollbar of an actively scrolled scroll frame,
+    // layerize the scrollbar thumb, wrap it in its own ContainerLayer and
+    // attach scrolling information to it.
+    // We do this here and not in the thumb's nsBoxFrame::BuildDisplayList so
+    // that the event region that gets created for the thumb is included in
+    // the nsDisplayOwnLayer contents.
+
+    uint32_t flags = 0;
+    mozilla::layers::FrameMetrics::ViewID scrollTargetId =
+      mozilla::layers::FrameMetrics::NULL_SCROLL_ID;
+    aBuilder->GetScrollbarInfo(&scrollTargetId, &flags);
+    bool thumbGetsLayer = (scrollTargetId != layers::FrameMetrics::NULL_SCROLL_ID);
+    nsLayoutUtils::SetScrollbarThumbLayerization(thumb, thumbGetsLayer);
+
+    if (thumbGetsLayer) {
+      nsDisplayListCollection tempLists;
+      nsBoxFrame::BuildDisplayListForChildren(aBuilder, aDirtyRect, tempLists);
+
+      // This is a bit of a hack. Collect up all descendant display items
+      // and merge them into a single Content() list.
+      nsDisplayList masterList;
+      masterList.AppendToTop(tempLists.BorderBackground());
+      masterList.AppendToTop(tempLists.BlockBorderBackgrounds());
+      masterList.AppendToTop(tempLists.Floats());
+      masterList.AppendToTop(tempLists.Content());
+      masterList.AppendToTop(tempLists.PositionedDescendants());
+      masterList.AppendToTop(tempLists.Outlines());
+
+      // Wrap the list to make it its own layer.
+      aLists.Content()->AppendNewToTop(new (aBuilder)
+        nsDisplayOwnLayer(aBuilder, this, &masterList, flags, scrollTargetId,
+                          GetThumbRatio()));
+
+      return;
+    }
+  }
+  
+  nsBoxFrame::BuildDisplayListForChildren(aBuilder, aDirtyRect, aLists);
+}
+
+NS_IMETHODIMP
+nsSliderFrame::DoXULLayout(nsBoxLayoutState& aState)
+{
+  // get the thumb should be our only child
+  nsIFrame* thumbBox = nsBox::GetChildXULBox(this);
+
+  if (!thumbBox) {
+    SyncLayout(aState);
+    return NS_OK;
+  }
+
+  EnsureOrient();
+
+#ifdef DEBUG_LAYOUT
+  if (mState & NS_STATE_DEBUG_WAS_SET) {
+      if (mState & NS_STATE_SET_TO_DEBUG)
+          SetXULDebug(aState, true);
+      else
+          SetXULDebug(aState, false);
+  }
+#endif
+
+  // get the content area inside our borders
+  nsRect clientRect;
+  GetXULClientRect(clientRect);
+
+  // get the scrollbar
+  nsIFrame* scrollbarBox = GetScrollbar();
+  nsCOMPtr<nsIContent> scrollbar;
+  scrollbar = GetContentOfBox(scrollbarBox);
+
+  // get the thumb's pref size
+  nsSize thumbSize = thumbBox->GetXULPrefSize(aState);
+
+  if (IsXULHorizontal())
+    thumbSize.height = clientRect.height;
+  else
+    thumbSize.width = clientRect.width;
+
+  int32_t curPos = GetCurrentPosition(scrollbar);
+  int32_t minPos = GetMinPosition(scrollbar);
+  int32_t maxPos = GetMaxPosition(scrollbar);
+  int32_t pageIncrement = GetPageIncrement(scrollbar);
+
+  maxPos = std::max(minPos, maxPos);
+  curPos = clamped(curPos, minPos, maxPos);
+
+  nscoord& availableLength = IsXULHorizontal() ? clientRect.width : clientRect.height;
+  nscoord& thumbLength = IsXULHorizontal() ? thumbSize.width : thumbSize.height;
+
+  if ((pageIncrement + maxPos - minPos) > 0 && thumbBox->GetXULFlex() > 0) {
+    float ratio = float(pageIncrement) / float(maxPos - minPos + pageIncrement);
+    thumbLength = std::max(thumbLength, NSToCoordRound(availableLength * ratio));
+  }
+
+  // Round the thumb's length to device pixels.
+  nsPresContext* presContext = PresContext();
+  thumbLength = presContext->DevPixelsToAppUnits(
+                  presContext->AppUnitsToDevPixels(thumbLength));
+
+  // mRatio translates the thumb position in app units to the value.
+  mRatio = (minPos != maxPos) ? float(availableLength - thumbLength) / float(maxPos - minPos) : 1;
+
+  // in reverse mode, curpos is reversed such that lower values are to the
+  // right or bottom and increase leftwards or upwards. In this case, use the
+  // offset from the end instead of the beginning.
+  bool reverse = mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::dir,
+                                         nsGkAtoms::reverse, eCaseMatters);
+  nscoord pos = reverse ? (maxPos - curPos) : (curPos - minPos);
+
+  // set the thumb's coord to be the current pos * the ratio.
+  nsRect thumbRect(clientRect.x, clientRect.y, thumbSize.width, thumbSize.height);
+  int32_t& thumbPos = (IsXULHorizontal() ? thumbRect.x : thumbRect.y);
+  thumbPos += NSToCoordRound(pos * mRatio);
+
+  nsRect oldThumbRect(thumbBox->GetRect());
+  LayoutChildAt(aState, thumbBox, thumbRect);
+
+  SyncLayout(aState);
+
+  // Redraw only if thumb changed size.
+  if (!oldThumbRect.IsEqualInterior(thumbRect))
+    XULRedraw(aState);
+
+  return NS_OK;
+}
+
+
+nsresult
+nsSliderFrame::HandleEvent(nsPresContext* aPresContext,
+                           WidgetGUIEvent* aEvent,
+                           nsEventStatus* aEventStatus)
+{
+  NS_ENSURE_ARG_POINTER(aEventStatus);
+
+  // If a web page calls event.preventDefault() we still want to
+  // scroll when scroll arrow is clicked. See bug 511075.
+  if (!mContent->IsInNativeAnonymousSubtree() &&
+      nsEventStatus_eConsumeNoDefault == *aEventStatus) {
+    return NS_OK;
+  }
+
+  if (!mDragFinished && !isDraggingThumb()) {
+    StopDrag();
+    return NS_OK;
+  }
+
+  nsIFrame* scrollbarBox = GetScrollbar();
+  nsCOMPtr<nsIContent> scrollbar;
+  scrollbar = GetContentOfBox(scrollbarBox);
+  bool isHorizontal = IsXULHorizontal();
+
+  if (isDraggingThumb())
+  {
+    switch (aEvent->mMessage) {
+    case eTouchMove:
+    case eMouseMove: {
+      if (mScrollingWithAPZ) {
+        break;
+      }
+      nsPoint eventPoint;
+      if (!GetEventPoint(aEvent, eventPoint)) {
+        break;
+      }
+      if (mChange) {
+        // On Linux the destination point is determined by the initial click
+        // on the scrollbar track and doesn't change until the mouse button
+        // is released.
+#ifndef MOZ_WIDGET_GTK
+        // On the other platforms we need to update the destination point now.
+        mDestinationPoint = eventPoint;
+        StopRepeat();
+        StartRepeat();
+#endif
+        break;
+      }
+
+      nscoord pos = isHorizontal ? eventPoint.x : eventPoint.y;
+
+      nsIFrame* thumbFrame = mFrames.FirstChild();
+      if (!thumbFrame) {
+        return NS_OK;
+      }
+
+      mozilla::Telemetry::Accumulate(mozilla::Telemetry::SCROLL_INPUT_METHODS,
+          (uint32_t) ScrollInputMethod::MainThreadScrollbarDrag);
+
+      // take our current position and subtract the start location
+      pos -= mDragStart;
+      bool isMouseOutsideThumb = false;
+      if (gSnapMultiplier) {
+        nsSize thumbSize = thumbFrame->GetSize();
+        if (isHorizontal) {
+          // horizontal scrollbar - check if mouse is above or below thumb
+          // XXXbz what about looking at the .y of the thumb's rect?  Is that
+          // always zero here?
+          if (eventPoint.y < -gSnapMultiplier * thumbSize.height ||
+              eventPoint.y > thumbSize.height +
+                               gSnapMultiplier * thumbSize.height)
+            isMouseOutsideThumb = true;
+        }
+        else {
+          // vertical scrollbar - check if mouse is left or right of thumb
+          if (eventPoint.x < -gSnapMultiplier * thumbSize.width ||
+              eventPoint.x > thumbSize.width +
+                               gSnapMultiplier * thumbSize.width)
+            isMouseOutsideThumb = true;
+        }
+      }
+      if (aEvent->mClass == eTouchEventClass) {
+        *aEventStatus = nsEventStatus_eConsumeNoDefault;
+      }
+      if (isMouseOutsideThumb)
+      {
+        SetCurrentThumbPosition(scrollbar, mThumbStart, false, false);
+        return NS_OK;
+      }
+
+      // set it
+      SetCurrentThumbPosition(scrollbar, pos, false, true); // with snapping
+    }
+    break;
+
+    case eTouchEnd:
+    case eMouseUp:
+      if (ShouldScrollForEvent(aEvent)) {
+        StopDrag();
+        //we MUST call nsFrame HandleEvent for mouse ups to maintain the selection state and capture state.
+        return nsFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+      }
+      break;
+
+    default:
+      break;
+    }
+
+    //return nsFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+    return NS_OK;
+  } else if (ShouldScrollToClickForEvent(aEvent)) {
+    nsPoint eventPoint;
+    if (!GetEventPoint(aEvent, eventPoint)) {
+      return NS_OK;
+    }
+    nscoord pos = isHorizontal ? eventPoint.x : eventPoint.y;
+
+    // adjust so that the middle of the thumb is placed under the click
+    nsIFrame* thumbFrame = mFrames.FirstChild();
+    if (!thumbFrame) {
+      return NS_OK;
+    }
+    nsSize thumbSize = thumbFrame->GetSize();
+    nscoord thumbLength = isHorizontal ? thumbSize.width : thumbSize.height;
+
+    mozilla::Telemetry::Accumulate(mozilla::Telemetry::SCROLL_INPUT_METHODS,
+        (uint32_t) ScrollInputMethod::MainThreadScrollbarTrackClick);
+
+    // set it
+    nsWeakFrame weakFrame(this);
+    // should aMaySnap be true here?
+    SetCurrentThumbPosition(scrollbar, pos - thumbLength/2, false, false);
+    NS_ENSURE_TRUE(weakFrame.IsAlive(), NS_OK);
+
+    DragThumb(true);
+
+#ifdef MOZ_WIDGET_GTK
+    nsCOMPtr<nsIContent> thumb = thumbFrame->GetContent();
+    thumb->SetAttr(kNameSpaceID_None, nsGkAtoms::active, NS_LITERAL_STRING("true"), true);
+#endif
+
+    if (aEvent->mClass == eTouchEventClass) {
+      *aEventStatus = nsEventStatus_eConsumeNoDefault;
+    }
+
+    if (isHorizontal)
+      mThumbStart = thumbFrame->GetPosition().x;
+    else
+      mThumbStart = thumbFrame->GetPosition().y;
+
+    mDragStart = pos - mThumbStart;
+  }
+#ifdef MOZ_WIDGET_GTK
+  else if (ShouldScrollForEvent(aEvent) &&
+           aEvent->mClass == eMouseEventClass &&
+           aEvent->AsMouseEvent()->button == WidgetMouseEvent::eRightButton) {
+    // HandlePress and HandleRelease are usually called via
+    // nsFrame::HandleEvent, but only for the left mouse button.
+    if (aEvent->mMessage == eMouseDown) {
+      HandlePress(aPresContext, aEvent, aEventStatus);
+    } else if (aEvent->mMessage == eMouseUp) {
+      HandleRelease(aPresContext, aEvent, aEventStatus);
+    }
+
+    return NS_OK;
+  }
+#endif
+
+  // XXX hack until handle release is actually called in nsframe.
+  //  if (aEvent->mMessage == eMouseOut ||
+  //      aEvent->mMessage == NS_MOUSE_RIGHT_BUTTON_UP ||
+  //      aEvent->mMessage == NS_MOUSE_LEFT_BUTTON_UP) {
+  //    HandleRelease(aPresContext, aEvent, aEventStatus);
+  //  }
+
+  if (aEvent->mMessage == eMouseOut && mChange)
+     HandleRelease(aPresContext, aEvent, aEventStatus);
+
+  return nsFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+}
+
+// Helper function to collect the "scroll to click" metric. Beware of
+// caching this, users expect to be able to change the system preference
+// and see the browser change its behavior immediately.
+bool
+nsSliderFrame::GetScrollToClick()
+{
+  if (GetScrollbar() != this) {
+    return LookAndFeel::GetInt(LookAndFeel::eIntID_ScrollToClick, false);
+  }
+
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::movetoclick,
+                            nsGkAtoms::_true, eCaseMatters)) {
+    return true;
+  }
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::movetoclick,
+                            nsGkAtoms::_false, eCaseMatters)) {
+    return false;
+  }
+
+#ifdef XP_MACOSX
+  return true;
+#else
+  return false;
+#endif
+}
+
+nsIFrame*
+nsSliderFrame::GetScrollbar()
+{
+  // if we are in a scrollbar then return the scrollbar's content node
+  // if we are not then return ours.
+   nsIFrame* scrollbar;
+   nsScrollbarButtonFrame::GetParentWithTag(nsGkAtoms::scrollbar, this, scrollbar);
+
+   if (scrollbar == nullptr)
+       return this;
+
+   return scrollbar->IsXULBoxFrame() ? scrollbar : this;
+}
+
+void
+nsSliderFrame::PageUpDown(nscoord change)
+{
+  // on a page up or down get our page increment. We get this by getting the scrollbar we are in and
+  // asking it for the current position and the page increment. If we are not in a scrollbar we will
+  // get the values from our own node.
+  nsIFrame* scrollbarBox = GetScrollbar();
+  nsCOMPtr<nsIContent> scrollbar;
+  scrollbar = GetContentOfBox(scrollbarBox);
+
+  nscoord pageIncrement = GetPageIncrement(scrollbar);
+  int32_t curpos = GetCurrentPosition(scrollbar);
+  int32_t minpos = GetMinPosition(scrollbar);
+  int32_t maxpos = GetMaxPosition(scrollbar);
+
+  // get the new position and make sure it is in bounds
+  int32_t newpos = curpos + change * pageIncrement;
+  if (newpos < minpos || maxpos < minpos)
+    newpos = minpos;
+  else if (newpos > maxpos)
+    newpos = maxpos;
+
+  SetCurrentPositionInternal(scrollbar, newpos, true);
+}
+
+// called when the current position changed and we need to update the thumb's location
+void
+nsSliderFrame::CurrentPositionChanged()
+{
+  nsIFrame* scrollbarBox = GetScrollbar();
+  nsCOMPtr<nsIContent> scrollbar;
+  scrollbar = GetContentOfBox(scrollbarBox);
+
+  // get the current position
+  int32_t curPos = GetCurrentPosition(scrollbar);
+
+  // do nothing if the position did not change
+  if (mCurPos == curPos)
+    return;
+
+  // get our current min and max position from our content node
+  int32_t minPos = GetMinPosition(scrollbar);
+  int32_t maxPos = GetMaxPosition(scrollbar);
+
+  maxPos = std::max(minPos, maxPos);
+  curPos = clamped(curPos, minPos, maxPos);
+
+  // get the thumb's rect
+  nsIFrame* thumbFrame = mFrames.FirstChild();
+  if (!thumbFrame)
+    return; // The thumb may stream in asynchronously via XBL.
+
+  nsRect thumbRect = thumbFrame->GetRect();
+
+  nsRect clientRect;
+  GetXULClientRect(clientRect);
+
+  // figure out the new rect
+  nsRect newThumbRect(thumbRect);
+
+  bool reverse = mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::dir,
+                                         nsGkAtoms::reverse, eCaseMatters);
+  nscoord pos = reverse ? (maxPos - curPos) : (curPos - minPos);
+
+  if (IsXULHorizontal())
+     newThumbRect.x = clientRect.x + NSToCoordRound(pos * mRatio);
+  else
+     newThumbRect.y = clientRect.y + NSToCoordRound(pos * mRatio);
+
+  // avoid putting the scroll thumb at subpixel positions which cause needless invalidations
+  nscoord appUnitsPerPixel = PresContext()->AppUnitsPerDevPixel();
+  nsPoint snappedThumbLocation = ToAppUnits(
+      newThumbRect.TopLeft().ToNearestPixels(appUnitsPerPixel),
+      appUnitsPerPixel);
+  if (IsXULHorizontal()) {
+    newThumbRect.x = snappedThumbLocation.x;
+  } else {
+    newThumbRect.y = snappedThumbLocation.y;
+  }
+
+  // set the rect
+  thumbFrame->SetRect(newThumbRect);
+
+  // Request a repaint of the scrollbar
+  nsScrollbarFrame* scrollbarFrame = do_QueryFrame(scrollbarBox);
+  nsIScrollbarMediator* mediator = scrollbarFrame
+      ? scrollbarFrame->GetScrollbarMediator() : nullptr;
+  if (!mediator || !mediator->ShouldSuppressScrollbarRepaints()) {
+    SchedulePaint();
+  }
+
+  mCurPos = curPos;
+
+  // inform the parent <scale> if it exists that the value changed
+  nsIFrame* parent = GetParent();
+  if (parent) {
+    nsCOMPtr<nsISliderListener> sliderListener = do_QueryInterface(parent->GetContent());
+    if (sliderListener) {
+      nsContentUtils::AddScriptRunner(
+        new nsValueChangedRunnable(sliderListener, nsGkAtoms::curpos, mCurPos, mUserChanged));
+    }
+  }
+}
+
+static void UpdateAttribute(nsIContent* aScrollbar, nscoord aNewPos, bool aNotify, bool aIsSmooth) {
+  nsAutoString str;
+  str.AppendInt(aNewPos);
+  
+  if (aIsSmooth) {
+    aScrollbar->SetAttr(kNameSpaceID_None, nsGkAtoms::smooth, NS_LITERAL_STRING("true"), false);
+  }
+  aScrollbar->SetAttr(kNameSpaceID_None, nsGkAtoms::curpos, str, aNotify);
+  if (aIsSmooth) {
+    aScrollbar->UnsetAttr(kNameSpaceID_None, nsGkAtoms::smooth, false);
+  }
+}
+
+// Use this function when you want to set the scroll position via the position
+// of the scrollbar thumb, e.g. when dragging the slider. This function scrolls
+// the content in such a way that thumbRect.x/.y becomes aNewThumbPos.
+void
+nsSliderFrame::SetCurrentThumbPosition(nsIContent* aScrollbar, nscoord aNewThumbPos,
+                                       bool aIsSmooth, bool aMaySnap)
+{
+  nsRect crect;
+  GetXULClientRect(crect);
+  nscoord offset = IsXULHorizontal() ? crect.x : crect.y;
+  int32_t newPos = NSToIntRound((aNewThumbPos - offset) / mRatio);
+  
+  if (aMaySnap && mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::snap,
+                                        nsGkAtoms::_true, eCaseMatters)) {
+    // If snap="true", then the slider may only be set to min + (increment * x).
+    // Otherwise, the slider may be set to any positive integer.
+    int32_t increment = GetIncrement(aScrollbar);
+    newPos = NSToIntRound(newPos / float(increment)) * increment;
+  }
+  
+  SetCurrentPosition(aScrollbar, newPos, aIsSmooth);
+}
+
+// Use this function when you know the target scroll position of the scrolled content.
+// aNewPos should be passed to this function as a position as if the minpos is 0.
+// That is, the minpos will be added to the position by this function. In a reverse
+// direction slider, the newpos should be the distance from the end.
+void
+nsSliderFrame::SetCurrentPosition(nsIContent* aScrollbar, int32_t aNewPos,
+                                  bool aIsSmooth)
+{
+   // get min and max position from our content node
+  int32_t minpos = GetMinPosition(aScrollbar);
+  int32_t maxpos = GetMaxPosition(aScrollbar);
+
+  // in reverse direction sliders, flip the value so that it goes from
+  // right to left, or bottom to top.
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::dir,
+                            nsGkAtoms::reverse, eCaseMatters))
+    aNewPos = maxpos - aNewPos;
+  else
+    aNewPos += minpos;
+
+  // get the new position and make sure it is in bounds
+  if (aNewPos < minpos || maxpos < minpos)
+    aNewPos = minpos;
+  else if (aNewPos > maxpos)
+    aNewPos = maxpos;
+
+  SetCurrentPositionInternal(aScrollbar, aNewPos, aIsSmooth);
+}
+
+void
+nsSliderFrame::SetCurrentPositionInternal(nsIContent* aScrollbar, int32_t aNewPos,
+                                          bool aIsSmooth)
+{
+  nsCOMPtr<nsIContent> scrollbar = aScrollbar;
+  nsIFrame* scrollbarBox = GetScrollbar();
+  nsWeakFrame weakFrame(this);
+
+  mUserChanged = true;
+
+  nsScrollbarFrame* scrollbarFrame = do_QueryFrame(scrollbarBox);
+  if (scrollbarFrame) {
+    // See if we have a mediator.
+    nsIScrollbarMediator* mediator = scrollbarFrame->GetScrollbarMediator();
+    if (mediator) {
+      nscoord oldPos = nsPresContext::CSSPixelsToAppUnits(GetCurrentPosition(scrollbar));
+      nscoord newPos = nsPresContext::CSSPixelsToAppUnits(aNewPos);
+      mediator->ThumbMoved(scrollbarFrame, oldPos, newPos);
+      if (!weakFrame.IsAlive()) {
+        return;
+      }
+      UpdateAttribute(scrollbar, aNewPos, /* aNotify */false, aIsSmooth);
+      CurrentPositionChanged();
+      mUserChanged = false;
+      return;
+    }
+  }
+
+  UpdateAttribute(scrollbar, aNewPos, true, aIsSmooth);
+  if (!weakFrame.IsAlive()) {
+    return;
+  }
+  mUserChanged = false;
+
+#ifdef DEBUG_SLIDER
+  printf("Current Pos=%d\n",aNewPos);
+#endif
+
+}
+
+nsIAtom*
+nsSliderFrame::GetType() const
+{
+  return nsGkAtoms::sliderFrame;
+}
+
+void
+nsSliderFrame::SetInitialChildList(ChildListID     aListID,
+                                   nsFrameList&    aChildList)
+{
+  nsBoxFrame::SetInitialChildList(aListID, aChildList);
+  if (aListID == kPrincipalList) {
+    AddListener();
+  }
+}
+
+nsresult
+nsSliderMediator::HandleEvent(nsIDOMEvent* aEvent)
+{
+  // Only process the event if the thumb is not being dragged.
+  if (mSlider && !mSlider->isDraggingThumb())
+    return mSlider->StartDrag(aEvent);
+
+  return NS_OK;
+}
+
+bool
+nsSliderFrame::StartAPZDrag()
+{
+  if (!gfxPlatform::GetPlatform()->SupportsApzDragInput()) {
+    return false;
+  }
+
+  nsContainerFrame* cf = GetScrollbar()->GetParent();
+  if (!cf) {
+    return false;
+  }
+
+  nsIContent* scrollableContent = cf->GetContent();
+  if (!scrollableContent) {
+    return false;
+  }
+
+  mozilla::layers::FrameMetrics::ViewID scrollTargetId;
+  bool hasID = nsLayoutUtils::FindIDFor(scrollableContent, &scrollTargetId);
+  bool hasAPZView = hasID && (scrollTargetId != layers::FrameMetrics::NULL_SCROLL_ID);
+
+  if (!hasAPZView) {
+    return false;
+  }
+
+  nsIFrame* scrollbarBox = GetScrollbar();
+  nsCOMPtr<nsIContent> scrollbar = GetContentOfBox(scrollbarBox);
+
+  // This rect is the range in which the scroll thumb can slide in.
+  nsRect sliderTrack = GetRect() - scrollbarBox->GetPosition();
+  CSSIntRect sliderTrackCSS = CSSIntRect::FromAppUnitsRounded(sliderTrack);
+
+  uint64_t inputblockId = InputAPZContext::GetInputBlockId();
+  uint32_t presShellId = PresContext()->PresShell()->GetPresShellId();
+  AsyncDragMetrics dragMetrics(scrollTargetId, presShellId, inputblockId,
+                               NSAppUnitsToIntPixels(mDragStart,
+                                 float(AppUnitsPerCSSPixel())),
+                               sliderTrackCSS,
+                               IsXULHorizontal() ? AsyncDragMetrics::HORIZONTAL :
+                                                   AsyncDragMetrics::VERTICAL);
+
+  if (!nsLayoutUtils::HasDisplayPort(scrollableContent)) {
+    return false;
+  }
+
+  // When we start an APZ drag, we wont get mouse events for the drag.
+  // APZ will consume them all and only notify us of the new scroll position.
+  this->GetNearestWidget()->StartAsyncScrollbarDrag(dragMetrics);
+  return true;
+}
+
+nsresult
+nsSliderFrame::StartDrag(nsIDOMEvent* aEvent)
+{
+#ifdef DEBUG_SLIDER
+  printf("Begin dragging\n");
+#endif
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                            nsGkAtoms::_true, eCaseMatters))
+    return NS_OK;
+
+  WidgetGUIEvent* event = aEvent->WidgetEventPtr()->AsGUIEvent();
+
+  if (!ShouldScrollForEvent(event)) {
+    return NS_OK;
+  }
+
+  nsPoint pt;
+  if (!GetEventPoint(event, pt)) {
+    return NS_OK;
+  }
+  bool isHorizontal = IsXULHorizontal();
+  nscoord pos = isHorizontal ? pt.x : pt.y;
+
+  // If we should scroll-to-click, first place the middle of the slider thumb
+  // under the mouse.
+  nsCOMPtr<nsIContent> scrollbar;
+  nscoord newpos = pos;
+  bool scrollToClick = ShouldScrollToClickForEvent(event);
+  if (scrollToClick) {
+    // adjust so that the middle of the thumb is placed under the click
+    nsIFrame* thumbFrame = mFrames.FirstChild();
+    if (!thumbFrame) {
+      return NS_OK;
+    }
+    nsSize thumbSize = thumbFrame->GetSize();
+    nscoord thumbLength = isHorizontal ? thumbSize.width : thumbSize.height;
+
+    newpos -= (thumbLength/2);
+
+    nsIFrame* scrollbarBox = GetScrollbar();
+    scrollbar = GetContentOfBox(scrollbarBox);
+  }
+
+  DragThumb(true);
+
+  if (scrollToClick) {
+    // should aMaySnap be true here?
+    SetCurrentThumbPosition(scrollbar, newpos, false, false);
+  }
+
+  nsIFrame* thumbFrame = mFrames.FirstChild();
+  if (!thumbFrame) {
+    return NS_OK;
+  }
+
+#ifdef MOZ_WIDGET_GTK
+  nsCOMPtr<nsIContent> thumb = thumbFrame->GetContent();
+  thumb->SetAttr(kNameSpaceID_None, nsGkAtoms::active, NS_LITERAL_STRING("true"), true);
+#endif
+
+  if (isHorizontal)
+    mThumbStart = thumbFrame->GetPosition().x;
+  else
+    mThumbStart = thumbFrame->GetPosition().y;
+
+  mDragStart = pos - mThumbStart;
+
+  mScrollingWithAPZ = StartAPZDrag();
+
+#ifdef DEBUG_SLIDER
+  printf("Pressed mDragStart=%d\n",mDragStart);
+#endif
+
+  if (!mScrollingWithAPZ && !mSuppressionActive) {
+    MOZ_ASSERT(PresContext()->PresShell());
+    APZCCallbackHelper::SuppressDisplayport(true, PresContext()->PresShell());
+    mSuppressionActive = true;
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsSliderFrame::StopDrag()
+{
+  AddListener();
+  DragThumb(false);
+
+  mScrollingWithAPZ = false;
+
+  if (mSuppressionActive) {
+    MOZ_ASSERT(PresContext()->PresShell());
+    APZCCallbackHelper::SuppressDisplayport(false, PresContext()->PresShell());
+    mSuppressionActive = false;
+  }
+
+#ifdef MOZ_WIDGET_GTK
+  nsIFrame* thumbFrame = mFrames.FirstChild();
+  if (thumbFrame) {
+    nsCOMPtr<nsIContent> thumb = thumbFrame->GetContent();
+    thumb->UnsetAttr(kNameSpaceID_None, nsGkAtoms::active, true);
+  }
+#endif
+
+  if (mChange) {
+    StopRepeat();
+    mChange = 0;
+  }
+  return NS_OK;
+}
+
+void
+nsSliderFrame::DragThumb(bool aGrabMouseEvents)
+{
+  mDragFinished = !aGrabMouseEvents;
+
+  // inform the parent <scale> that a drag is beginning or ending
+  nsIFrame* parent = GetParent();
+  if (parent) {
+    nsCOMPtr<nsISliderListener> sliderListener = do_QueryInterface(parent->GetContent());
+    if (sliderListener) {
+      nsContentUtils::AddScriptRunner(
+        new nsDragStateChangedRunnable(sliderListener, aGrabMouseEvents));
+    }
+  }
+
+  nsIPresShell::SetCapturingContent(aGrabMouseEvents ? GetContent() : nullptr,
+                                    aGrabMouseEvents ? CAPTURE_IGNOREALLOWED : 0);
+}
+
+bool
+nsSliderFrame::isDraggingThumb()
+{
+  return (nsIPresShell::GetCapturingContent() == GetContent());
+}
+
+void
+nsSliderFrame::AddListener()
+{
+  if (!mMediator) {
+    mMediator = new nsSliderMediator(this);
+  }
+
+  nsIFrame* thumbFrame = mFrames.FirstChild();
+  if (!thumbFrame) {
+    return;
+  }
+  thumbFrame->GetContent()->
+    AddSystemEventListener(NS_LITERAL_STRING("mousedown"), mMediator,
+                           false, false);
+  thumbFrame->GetContent()->
+    AddSystemEventListener(NS_LITERAL_STRING("touchstart"), mMediator,
+                           false, false);
+}
+
+void
+nsSliderFrame::RemoveListener()
+{
+  NS_ASSERTION(mMediator, "No listener was ever added!!");
+
+  nsIFrame* thumbFrame = mFrames.FirstChild();
+  if (!thumbFrame)
+    return;
+
+  thumbFrame->GetContent()->
+    RemoveSystemEventListener(NS_LITERAL_STRING("mousedown"), mMediator, false);
+}
+
+bool
+nsSliderFrame::ShouldScrollForEvent(WidgetGUIEvent* aEvent)
+{
+  switch (aEvent->mMessage) {
+    case eTouchStart:
+    case eTouchEnd:
+      return true;
+    case eMouseDown:
+    case eMouseUp: {
+      uint16_t button = aEvent->AsMouseEvent()->button;
+#ifdef MOZ_WIDGET_GTK
+      return (button == WidgetMouseEvent::eLeftButton) ||
+             (button == WidgetMouseEvent::eRightButton && GetScrollToClick()) ||
+             (button == WidgetMouseEvent::eMiddleButton && gMiddlePref && !GetScrollToClick());
+#else
+      return (button == WidgetMouseEvent::eLeftButton) ||
+             (button == WidgetMouseEvent::eMiddleButton && gMiddlePref);
+#endif
+    }
+    default:
+      return false;
+  }
+}
+
+bool
+nsSliderFrame::ShouldScrollToClickForEvent(WidgetGUIEvent* aEvent)
+{
+  if (!ShouldScrollForEvent(aEvent)) {
+    return false;
+  }
+
+  if (aEvent->mMessage == eTouchStart) {
+    return GetScrollToClick();
+  }
+
+  if (aEvent->mMessage != eMouseDown) {
+    return false;
+  }
+
+#if defined(XP_MACOSX) || defined(MOZ_WIDGET_GTK)
+  // On Mac and Linux, clicking the scrollbar thumb should never scroll to click.
+  if (IsEventOverThumb(aEvent)) {
+    return false;
+  }
+#endif
+
+  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+  if (mouseEvent->button == WidgetMouseEvent::eLeftButton) {
+#ifdef XP_MACOSX
+    bool invertPref = mouseEvent->IsAlt();
+#else
+    bool invertPref = mouseEvent->IsShift();
+#endif
+    return GetScrollToClick() != invertPref;
+  }
+
+#ifdef MOZ_WIDGET_GTK
+  if (mouseEvent->button == WidgetMouseEvent::eRightButton) {
+    return !GetScrollToClick();
+  }
+#endif
+
+  return true;
+}
+
+bool
+nsSliderFrame::IsEventOverThumb(WidgetGUIEvent* aEvent)
+{
+  nsIFrame* thumbFrame = mFrames.FirstChild();
+  if (!thumbFrame) {
+    return false;
+  }
+
+  nsPoint eventPoint;
+  if (!GetEventPoint(aEvent, eventPoint)) {
+    return false;
+  }
+
+  nsRect thumbRect = thumbFrame->GetRect();
+#if defined(MOZ_WIDGET_GTK)
+  /* Scrollbar track can have padding, so it's better to check that eventPoint
+   * is inside of actual thumb, not just its one axis. The part of the scrollbar
+   * track adjacent to thumb can actually receive events in GTK3 */
+  return eventPoint.x >= thumbRect.x && eventPoint.x < thumbRect.XMost() &&
+         eventPoint.y >= thumbRect.y && eventPoint.y < thumbRect.YMost();
+#else
+  bool isHorizontal = IsXULHorizontal();
+  nscoord eventPos = isHorizontal ? eventPoint.x : eventPoint.y;
+  nscoord thumbStart = isHorizontal ? thumbRect.x : thumbRect.y;
+  nscoord thumbEnd = isHorizontal ? thumbRect.XMost() : thumbRect.YMost();
+
+  return eventPos >= thumbStart && eventPos < thumbEnd;
+#endif
+}
+
+NS_IMETHODIMP
+nsSliderFrame::HandlePress(nsPresContext* aPresContext,
+                           WidgetGUIEvent* aEvent,
+                           nsEventStatus* aEventStatus)
+{
+  if (!ShouldScrollForEvent(aEvent) || ShouldScrollToClickForEvent(aEvent)) {
+    return NS_OK;
+  }
+
+  if (IsEventOverThumb(aEvent)) {
+    return NS_OK;
+  }
+
+  nsIFrame* thumbFrame = mFrames.FirstChild();
+  if (!thumbFrame) // display:none?
+    return NS_OK;
+
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                            nsGkAtoms::_true, eCaseMatters))
+    return NS_OK;
+  
+  nsRect thumbRect = thumbFrame->GetRect();
+  
+  nscoord change = 1;
+  nsPoint eventPoint;
+  if (!GetEventPoint(aEvent, eventPoint)) {
+    return NS_OK;
+  }
+  if (IsXULHorizontal() ? eventPoint.x < thumbRect.x 
+                        : eventPoint.y < thumbRect.y)
+    change = -1;
+
+  mChange = change;
+  DragThumb(true);
+  // On Linux we want to keep scrolling in the direction indicated by |change|
+  // until the mouse is released. On the other platforms we want to stop
+  // scrolling as soon as the scrollbar thumb has reached the current mouse
+  // position.
+#ifdef MOZ_WIDGET_GTK
+  nsRect clientRect;
+  GetXULClientRect(clientRect);
+
+  // Set the destination point to the very end of the scrollbar so that
+  // scrolling doesn't stop halfway through.
+  if (change > 0) {
+    mDestinationPoint = nsPoint(clientRect.width, clientRect.height);
+  }
+  else {
+    mDestinationPoint = nsPoint(0, 0);
+  }
+#else
+  mDestinationPoint = eventPoint;
+#endif
+  StartRepeat();
+  PageScroll(change);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSliderFrame::HandleRelease(nsPresContext* aPresContext,
+                             WidgetGUIEvent* aEvent,
+                             nsEventStatus* aEventStatus)
+{
+  StopRepeat();
+
+  nsIFrame* scrollbar = GetScrollbar();
+  nsScrollbarFrame* sb = do_QueryFrame(scrollbar);
+  if (sb) {
+    nsIScrollbarMediator* m = sb->GetScrollbarMediator();
+    if (m) {
+      m->ScrollbarReleased(sb);
+    }
+  }
+  return NS_OK;
+}
+
+void
+nsSliderFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  // tell our mediator if we have one we are gone.
+  if (mMediator) {
+    mMediator->SetSlider(nullptr);
+    mMediator = nullptr;
+  }
+  StopRepeat();
+
+  // call base class Destroy()
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+nsSize
+nsSliderFrame::GetXULPrefSize(nsBoxLayoutState& aState)
+{
+  EnsureOrient();
+  return nsBoxFrame::GetXULPrefSize(aState);
+}
+
+nsSize
+nsSliderFrame::GetXULMinSize(nsBoxLayoutState& aState)
+{
+  EnsureOrient();
+
+  // our min size is just our borders and padding
+  return nsBox::GetXULMinSize(aState);
+}
+
+nsSize
+nsSliderFrame::GetXULMaxSize(nsBoxLayoutState& aState)
+{
+  EnsureOrient();
+  return nsBoxFrame::GetXULMaxSize(aState);
+}
+
+void
+nsSliderFrame::EnsureOrient()
+{
+  nsIFrame* scrollbarBox = GetScrollbar();
+
+  bool isHorizontal = (scrollbarBox->GetStateBits() & NS_STATE_IS_HORIZONTAL) != 0;
+  if (isHorizontal)
+      mState |= NS_STATE_IS_HORIZONTAL;
+  else
+      mState &= ~NS_STATE_IS_HORIZONTAL;
+}
+
+
+void
+nsSliderFrame::Notify(void)
+{
+    bool stop = false;
+
+    nsIFrame* thumbFrame = mFrames.FirstChild();
+    if (!thumbFrame) {
+      StopRepeat();
+      return;
+    }
+    nsRect thumbRect = thumbFrame->GetRect();
+
+    bool isHorizontal = IsXULHorizontal();
+
+    // See if the thumb has moved past our destination point.
+    // if it has we want to stop.
+    if (isHorizontal) {
+        if (mChange < 0) {
+            if (thumbRect.x < mDestinationPoint.x)
+                stop = true;
+        } else {
+            if (thumbRect.x + thumbRect.width > mDestinationPoint.x)
+                stop = true;
+        }
+    } else {
+         if (mChange < 0) {
+            if (thumbRect.y < mDestinationPoint.y)
+                stop = true;
+        } else {
+            if (thumbRect.y + thumbRect.height > mDestinationPoint.y)
+                stop = true;
+        }
+    }
+
+
+    if (stop) {
+      StopRepeat();
+    } else {
+      PageScroll(mChange);
+    }
+}
+
+void
+nsSliderFrame::PageScroll(nscoord aChange)
+{
+  if (mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::dir,
+                            nsGkAtoms::reverse, eCaseMatters)) {
+    aChange = -aChange;
+  }
+  nsIFrame* scrollbar = GetScrollbar();
+  nsScrollbarFrame* sb = do_QueryFrame(scrollbar);
+  if (sb) {
+    nsIScrollbarMediator* m = sb->GetScrollbarMediator();
+    sb->SetIncrementToPage(aChange);
+    if (m) {
+      m->ScrollByPage(sb, aChange, nsIScrollbarMediator::ENABLE_SNAP);
+      return;
+    }
+  }
+  PageUpDown(aChange);
+}
+
+float
+nsSliderFrame::GetThumbRatio() const
+{
+  // mRatio is in thumb app units per scrolled css pixels. Convert it to a
+  // ratio of the thumb's CSS pixels per scrolled CSS pixels. (Note the thumb
+  // is in the scrollframe's parent's space whereas the scrolled CSS pixels
+  // are in the scrollframe's space).
+  return mRatio / mozilla::AppUnitsPerCSSPixel();
+}
+
+NS_IMPL_ISUPPORTS(nsSliderMediator,
+                  nsIDOMEventListener)
diff --git a/layout/xul/nsSliderFrame.h b/layout/xul/nsSliderFrame.h
new file mode 100644
index 0000000000..832065a210
--- /dev/null
+++ b/layout/xul/nsSliderFrame.h
@@ -0,0 +1,206 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSliderFrame_h__
+#define nsSliderFrame_h__
+
+#include "mozilla/Attributes.h"
+#include "nsRepeatService.h"
+#include "nsBoxFrame.h"
+#include "nsIAtom.h"
+#include "nsCOMPtr.h"
+#include "nsITimer.h"
+#include "nsIDOMEventListener.h"
+
+class nsITimer;
+class nsSliderFrame;
+
+nsIFrame* NS_NewSliderFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+class nsSliderMediator final : public nsIDOMEventListener
+{
+public:
+
+  NS_DECL_ISUPPORTS
+
+  nsSliderFrame* mSlider;
+
+  explicit nsSliderMediator(nsSliderFrame* aSlider) {  mSlider = aSlider; }
+
+  virtual void SetSlider(nsSliderFrame* aSlider) { mSlider = aSlider; }
+
+  NS_IMETHOD HandleEvent(nsIDOMEvent* aEvent) override;
+
+protected:
+  virtual ~nsSliderMediator() {}
+};
+
+class nsSliderFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+  NS_DECL_QUERYFRAME_TARGET(nsSliderFrame)
+  NS_DECL_QUERYFRAME
+
+  friend class nsSliderMediator;
+
+  explicit nsSliderFrame(nsStyleContext* aContext);
+  virtual ~nsSliderFrame();
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override {
+    return MakeFrameName(NS_LITERAL_STRING("SliderFrame"), aResult);
+  }
+#endif
+
+  virtual nsSize GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMaxSize(nsBoxLayoutState& aBoxLayoutState) override;
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aBoxLayoutState) override;
+
+  // nsIFrame overrides
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) override;
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+ 
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         asPrevInFlow) override;
+
+
+  virtual nsresult HandleEvent(nsPresContext* aPresContext,
+                               mozilla::WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  virtual nsIAtom* GetType() const override;
+
+  // nsContainerFrame overrides
+  virtual void SetInitialChildList(ChildListID     aListID,
+                                   nsFrameList&    aChildList) override;
+  virtual void AppendFrames(ChildListID     aListID,
+                            nsFrameList&    aFrameList) override;
+  virtual void InsertFrames(ChildListID     aListID,
+                            nsIFrame*       aPrevFrame,
+                            nsFrameList&    aFrameList) override;
+  virtual void RemoveFrame(ChildListID     aListID,
+                           nsIFrame*       aOldFrame) override;
+
+  nsresult StartDrag(nsIDOMEvent* aEvent);
+  nsresult StopDrag();
+
+  bool StartAPZDrag();
+
+  static int32_t GetCurrentPosition(nsIContent* content);
+  static int32_t GetMinPosition(nsIContent* content);
+  static int32_t GetMaxPosition(nsIContent* content);
+  static int32_t GetIncrement(nsIContent* content);
+  static int32_t GetPageIncrement(nsIContent* content);
+  static int32_t GetIntegerAttribute(nsIContent* content, nsIAtom* atom, int32_t defaultValue);
+  void EnsureOrient();
+
+  NS_IMETHOD HandlePress(nsPresContext* aPresContext,
+                         mozilla::WidgetGUIEvent* aEvent,
+                         nsEventStatus* aEventStatus) override;
+
+  NS_IMETHOD HandleMultiplePress(nsPresContext* aPresContext,
+                                 mozilla::WidgetGUIEvent* aEvent,
+                                 nsEventStatus* aEventStatus,
+                                 bool aControlHeld) override
+  {
+    return NS_OK;
+  }
+
+  NS_IMETHOD HandleDrag(nsPresContext* aPresContext,
+                        mozilla::WidgetGUIEvent* aEvent,
+                        nsEventStatus* aEventStatus) override
+  {
+    return NS_OK;
+  }
+
+  NS_IMETHOD HandleRelease(nsPresContext* aPresContext,
+                           mozilla::WidgetGUIEvent* aEvent,
+                           nsEventStatus* aEventStatus) override;
+
+  // Return the ratio the scrollbar thumb should move in proportion to the
+  // scrolled frame.
+  float GetThumbRatio() const;
+
+private:
+
+  bool GetScrollToClick();
+  nsIFrame* GetScrollbar();
+  bool ShouldScrollForEvent(mozilla::WidgetGUIEvent* aEvent);
+  bool ShouldScrollToClickForEvent(mozilla::WidgetGUIEvent* aEvent);
+  bool IsEventOverThumb(mozilla::WidgetGUIEvent* aEvent);
+
+  void PageUpDown(nscoord change);
+  void SetCurrentThumbPosition(nsIContent* aScrollbar, nscoord aNewPos, bool aIsSmooth,
+                               bool aMaySnap);
+  void SetCurrentPosition(nsIContent* aScrollbar, int32_t aNewPos, bool aIsSmooth);
+  void SetCurrentPositionInternal(nsIContent* aScrollbar, int32_t pos,
+                                  bool aIsSmooth);
+  void CurrentPositionChanged();
+
+  void DragThumb(bool aGrabMouseEvents);
+  void AddListener();
+  void RemoveListener();
+  bool isDraggingThumb();
+
+  void StartRepeat() {
+    nsRepeatService::GetInstance()->Start(Notify, this);
+  }
+  void StopRepeat() {
+    nsRepeatService::GetInstance()->Stop(Notify, this);
+  }
+  void Notify();
+  static void Notify(void* aData) {
+    (static_cast<nsSliderFrame*>(aData))->Notify();
+  }
+  void PageScroll(nscoord aChange);
+ 
+  nsPoint mDestinationPoint;
+  RefPtr<nsSliderMediator> mMediator;
+
+  float mRatio;
+
+  nscoord mDragStart;
+  nscoord mThumbStart;
+
+  int32_t mCurPos;
+
+  nscoord mChange;
+
+  bool mDragFinished;
+
+  // true if an attribute change has been caused by the user manipulating the
+  // slider. This allows notifications to tell how a slider's current position
+  // was changed.
+  bool mUserChanged;
+
+  // true if we've handed off the scrolling to APZ. This means that we should
+  // ignore scrolling events as the position will be updated by APZ. If we were
+  // to process these events then the scroll position update would conflict
+  // causing the scroll position to jump.
+  bool mScrollingWithAPZ;
+
+  // true if displayport suppression is active, for more performant
+  // scrollbar-dragging behaviour.
+  bool mSuppressionActive;
+
+  static bool gMiddlePref;
+  static int32_t gSnapMultiplier;
+}; // class nsSliderFrame
+
+#endif
diff --git a/layout/xul/nsSplitterFrame.cpp b/layout/xul/nsSplitterFrame.cpp
new file mode 100644
index 0000000000..7879a176d3
--- /dev/null
+++ b/layout/xul/nsSplitterFrame.cpp
@@ -0,0 +1,1046 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsSplitterFrame.h"
+#include "nsGkAtoms.h"
+#include "nsIDOMElement.h"
+#include "nsIDOMXULElement.h"
+#include "nsPresContext.h"
+#include "nsRenderingContext.h"
+#include "nsIDocument.h"
+#include "nsNameSpaceManager.h"
+#include "nsScrollbarButtonFrame.h"
+#include "nsIDOMEventListener.h"
+#include "nsIDOMMouseEvent.h"
+#include "nsIPresShell.h"
+#include "nsFrameList.h"
+#include "nsHTMLParts.h"
+#include "nsStyleContext.h"
+#include "nsBoxLayoutState.h"
+#include "nsIServiceManager.h"
+#include "nsContainerFrame.h"
+#include "nsContentCID.h"
+#include "mozilla/StyleSetHandle.h"
+#include "mozilla/StyleSetHandleInlines.h"
+#include "nsLayoutUtils.h"
+#include "nsDisplayList.h"
+#include "nsContentUtils.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/UniquePtr.h"
+
+using namespace mozilla;
+
+class nsSplitterInfo {
+public:
+  nscoord min;
+  nscoord max;
+  nscoord current;
+  nscoord changed;
+  nsCOMPtr<nsIContent> childElem;
+  int32_t flex;
+  int32_t index;
+};
+
+class nsSplitterFrameInner final : public nsIDOMEventListener
+{
+protected:
+  virtual ~nsSplitterFrameInner();
+
+public:
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIDOMEVENTLISTENER
+
+  explicit nsSplitterFrameInner(nsSplitterFrame* aSplitter)
+  {
+    mOuter = aSplitter;
+    mPressed = false;
+  }
+
+  void Disconnect() { mOuter = nullptr; }
+
+  nsresult MouseDown(nsIDOMEvent* aMouseEvent);
+  nsresult MouseUp(nsIDOMEvent* aMouseEvent);
+  nsresult MouseMove(nsIDOMEvent* aMouseEvent);
+
+  void MouseDrag(nsPresContext* aPresContext, WidgetGUIEvent* aEvent);
+  void MouseUp(nsPresContext* aPresContext, WidgetGUIEvent* aEvent);
+
+  void AdjustChildren(nsPresContext* aPresContext);
+  void AdjustChildren(nsPresContext* aPresContext, nsSplitterInfo* aChildInfos, int32_t aCount, bool aIsHorizontal);
+
+  void AddRemoveSpace(nscoord aDiff,
+                    nsSplitterInfo* aChildInfos,
+                    int32_t aCount,
+                    int32_t& aSpaceLeft);
+
+  void ResizeChildTo(nscoord& aDiff,
+                     nsSplitterInfo* aChildrenBeforeInfos,
+                     nsSplitterInfo* aChildrenAfterInfos,
+                     int32_t aChildrenBeforeCount,
+                     int32_t aChildrenAfterCount,
+                     bool aBounded);
+
+  void UpdateState();
+
+  void AddListener();
+  void RemoveListener();
+
+  enum ResizeType { Closest, Farthest, Flex, Grow };
+  enum State { Open, CollapsedBefore, CollapsedAfter, Dragging };
+  enum CollapseDirection { Before, After };
+
+  ResizeType GetResizeBefore();
+  ResizeType GetResizeAfter();
+  State GetState();
+
+  void Reverse(UniquePtr<nsSplitterInfo[]>& aIndexes, int32_t aCount);
+  bool SupportsCollapseDirection(CollapseDirection aDirection);
+
+  void EnsureOrient();
+  void SetPreferredSize(nsBoxLayoutState& aState, nsIFrame* aChildBox, nscoord aOnePixel, bool aIsHorizontal, nscoord* aSize);
+
+  nsSplitterFrame* mOuter;
+  bool mDidDrag;
+  nscoord mDragStart;
+  nscoord mCurrentPos;
+  nsIFrame* mParentBox;
+  bool mPressed;
+  UniquePtr<nsSplitterInfo[]> mChildInfosBefore;
+  UniquePtr<nsSplitterInfo[]> mChildInfosAfter;
+  int32_t mChildInfosBeforeCount;
+  int32_t mChildInfosAfterCount;
+  State mState;
+  nscoord mSplitterPos;
+  bool mDragging;
+
+};
+
+NS_IMPL_ISUPPORTS(nsSplitterFrameInner, nsIDOMEventListener)
+
+nsSplitterFrameInner::ResizeType
+nsSplitterFrameInner::GetResizeBefore()
+{
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::farthest, &nsGkAtoms::flex, nullptr};
+  switch (mOuter->GetContent()->FindAttrValueIn(kNameSpaceID_None,
+                                                nsGkAtoms::resizebefore,
+                                                strings, eCaseMatters)) {
+    case 0: return Farthest;
+    case 1: return Flex;
+  }
+  return Closest;
+}
+
+nsSplitterFrameInner::~nsSplitterFrameInner() 
+{
+}
+
+nsSplitterFrameInner::ResizeType
+nsSplitterFrameInner::GetResizeAfter()
+{
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::farthest, &nsGkAtoms::flex, &nsGkAtoms::grow, nullptr};
+  switch (mOuter->GetContent()->FindAttrValueIn(kNameSpaceID_None,
+                                                nsGkAtoms::resizeafter,
+                                                strings, eCaseMatters)) {
+    case 0: return Farthest;
+    case 1: return Flex;
+    case 2: return Grow;
+  }
+  return Closest;
+}
+
+nsSplitterFrameInner::State
+nsSplitterFrameInner::GetState()
+{
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::dragging, &nsGkAtoms::collapsed, nullptr};
+  static nsIContent::AttrValuesArray strings_substate[] =
+    {&nsGkAtoms::before, &nsGkAtoms::after, nullptr};
+  switch (mOuter->GetContent()->FindAttrValueIn(kNameSpaceID_None,
+                                                nsGkAtoms::state,
+                                                strings, eCaseMatters)) {
+    case 0: return Dragging;
+    case 1:
+      switch (mOuter->GetContent()->FindAttrValueIn(kNameSpaceID_None,
+                                                    nsGkAtoms::substate,
+                                                    strings_substate,
+                                                    eCaseMatters)) {
+        case 0: return CollapsedBefore;
+        case 1: return CollapsedAfter;
+        default:
+          if (SupportsCollapseDirection(After))
+            return CollapsedAfter;
+          return CollapsedBefore;
+      }
+  }
+  return Open;
+}
+
+//
+// NS_NewSplitterFrame
+//
+// Creates a new Toolbar frame and returns it
+//
+nsIFrame*
+NS_NewSplitterFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsSplitterFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsSplitterFrame)
+
+nsSplitterFrame::nsSplitterFrame(nsStyleContext* aContext)
+: nsBoxFrame(aContext),
+  mInner(0)
+{
+}
+
+void
+nsSplitterFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  if (mInner) {
+    mInner->RemoveListener();
+    mInner->Disconnect();
+    mInner->Release();
+    mInner = nullptr;
+  }
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+
+nsresult
+nsSplitterFrame::GetCursor(const nsPoint&    aPoint,
+                           nsIFrame::Cursor& aCursor)
+{
+  return nsBoxFrame::GetCursor(aPoint, aCursor);
+
+  /*
+    if (IsXULHorizontal())
+      aCursor = NS_STYLE_CURSOR_N_RESIZE;
+    else
+      aCursor = NS_STYLE_CURSOR_W_RESIZE;
+
+    return NS_OK;
+  */
+}
+
+nsresult
+nsSplitterFrame::AttributeChanged(int32_t aNameSpaceID,
+                                  nsIAtom* aAttribute,
+                                  int32_t aModType)
+{
+  nsresult rv = nsBoxFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                             aModType);
+  // if the alignment changed. Let the grippy know
+  if (aAttribute == nsGkAtoms::align) {
+    // tell the slider its attribute changed so it can 
+    // update itself
+    nsIFrame* grippy = nullptr;
+    nsScrollbarButtonFrame::GetChildWithTag(nsGkAtoms::grippy, this, grippy);
+    if (grippy)
+      grippy->AttributeChanged(aNameSpaceID, aAttribute, aModType);
+  } else if (aAttribute == nsGkAtoms::state) {
+    mInner->UpdateState();
+  }
+
+  return rv;
+}
+
+/**
+ * Initialize us. If we are in a box get our alignment so we know what direction we are
+ */
+void
+nsSplitterFrame::Init(nsIContent*       aContent,
+                      nsContainerFrame* aParent,
+                      nsIFrame*         aPrevInFlow)
+{
+  MOZ_ASSERT(!mInner);
+  mInner = new nsSplitterFrameInner(this);
+
+  mInner->AddRef();
+  mInner->mState = nsSplitterFrameInner::Open;
+  mInner->mDragging = false;
+
+  // determine orientation of parent, and if vertical, set orient to vertical
+  // on splitter content, then re-resolve style
+  // XXXbz this is pretty messed up, since this can change whether we should
+  // have a frame at all.  This really needs a better solution.
+  if (aParent && aParent->IsXULBoxFrame()) {
+    if (!aParent->IsXULHorizontal()) {
+      if (!nsContentUtils::HasNonEmptyAttr(aContent, kNameSpaceID_None,
+                                           nsGkAtoms::orient)) {
+        aContent->SetAttr(kNameSpaceID_None, nsGkAtoms::orient,
+                          NS_LITERAL_STRING("vertical"), false);
+        nsStyleContext* parentStyleContext = StyleContext()->GetParent();
+        RefPtr<nsStyleContext> newContext = PresContext()->StyleSet()->
+          ResolveStyleFor(aContent->AsElement(), parentStyleContext);
+        SetStyleContextWithoutNotification(newContext);
+      }
+    }
+  }
+
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  mInner->mState = nsSplitterFrameInner::Open;
+  mInner->AddListener();
+  mInner->mParentBox = nullptr;
+}
+
+NS_IMETHODIMP
+nsSplitterFrame::DoXULLayout(nsBoxLayoutState& aState)
+{
+  if (GetStateBits() & NS_FRAME_FIRST_REFLOW) 
+  {
+    mInner->mParentBox = nsBox::GetParentXULBox(this);
+    mInner->UpdateState();
+  }
+
+  return nsBoxFrame::DoXULLayout(aState);
+}
+
+
+void
+nsSplitterFrame::GetInitialOrientation(bool& aIsHorizontal)
+{
+  nsIFrame* box = nsBox::GetParentXULBox(this);
+  if (box) {
+    aIsHorizontal = !box->IsXULHorizontal();
+  }
+  else
+    nsBoxFrame::GetInitialOrientation(aIsHorizontal);
+}
+
+NS_IMETHODIMP
+nsSplitterFrame::HandlePress(nsPresContext* aPresContext,
+                             WidgetGUIEvent* aEvent,
+                             nsEventStatus* aEventStatus)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSplitterFrame::HandleMultiplePress(nsPresContext* aPresContext,
+                                     WidgetGUIEvent* aEvent,
+                                     nsEventStatus* aEventStatus,
+                                     bool aControlHeld)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSplitterFrame::HandleDrag(nsPresContext* aPresContext,
+                            WidgetGUIEvent* aEvent,
+                            nsEventStatus* aEventStatus)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsSplitterFrame::HandleRelease(nsPresContext* aPresContext,
+                               WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus)
+{
+  return NS_OK;
+}
+
+void
+nsSplitterFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                  const nsRect&           aDirtyRect,
+                                  const nsDisplayListSet& aLists)
+{
+  nsBoxFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);
+  
+  // if the mouse is captured always return us as the frame.
+  if (mInner->mDragging)
+  {
+    // XXX It's probably better not to check visibility here, right?
+    aLists.Outlines()->AppendNewToTop(new (aBuilder)
+      nsDisplayEventReceiver(aBuilder, this));
+    return;
+  }
+}
+
+nsresult
+nsSplitterFrame::HandleEvent(nsPresContext* aPresContext,
+                             WidgetGUIEvent* aEvent,
+                             nsEventStatus* aEventStatus)
+{
+  NS_ENSURE_ARG_POINTER(aEventStatus);
+  if (nsEventStatus_eConsumeNoDefault == *aEventStatus) {
+    return NS_OK;
+  }
+
+  nsWeakFrame weakFrame(this);
+  RefPtr<nsSplitterFrameInner> inner(mInner);
+  switch (aEvent->mMessage) {
+    case eMouseMove: 
+      inner->MouseDrag(aPresContext, aEvent);
+      break;
+  
+    case eMouseUp:
+      if (aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton) {
+        inner->MouseUp(aPresContext, aEvent);
+      }
+      break;
+
+    default:
+      break;
+  }
+
+  NS_ENSURE_STATE(weakFrame.IsAlive());
+  return nsBoxFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+}
+
+void
+nsSplitterFrameInner::MouseUp(nsPresContext* aPresContext,
+                              WidgetGUIEvent* aEvent)
+{
+  if (mDragging && mOuter) {
+    AdjustChildren(aPresContext);
+    AddListener();
+    nsIPresShell::SetCapturingContent(nullptr, 0); // XXXndeakin is this needed?
+    mDragging = false;
+    State newState = GetState(); 
+    // if the state is dragging then make it Open.
+    if (newState == Dragging)
+      mOuter->mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::state, EmptyString(), true);
+
+    mPressed = false;
+
+    // if we dragged then fire a command event.
+    if (mDidDrag) {
+      nsCOMPtr<nsIDOMXULElement> element = do_QueryInterface(mOuter->GetContent());
+      element->DoCommand();
+    }
+
+    //printf("MouseUp\n");
+  }
+
+  mChildInfosBefore = nullptr;
+  mChildInfosAfter = nullptr;
+  mChildInfosBeforeCount = 0;
+  mChildInfosAfterCount = 0;
+}
+
+void
+nsSplitterFrameInner::MouseDrag(nsPresContext* aPresContext,
+                                WidgetGUIEvent* aEvent)
+{
+  if (mDragging && mOuter) {
+
+    //printf("Dragging\n");
+
+    bool isHorizontal = !mOuter->IsXULHorizontal();
+    // convert coord to pixels
+    nsPoint pt = nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent,
+                                                              mParentBox);
+    nscoord pos = isHorizontal ? pt.x : pt.y;
+
+    // mDragStart is in frame coordinates
+    nscoord start = mDragStart;
+
+    // take our current position and subtract the start location
+    pos -= start;
+
+    //printf("Diff=%d\n", pos);
+
+    ResizeType resizeAfter  = GetResizeAfter();
+
+    bool bounded;
+
+    if (resizeAfter == nsSplitterFrameInner::Grow)
+      bounded = false;
+    else 
+      bounded = true;
+
+    int i;
+    for (i=0; i < mChildInfosBeforeCount; i++) 
+      mChildInfosBefore[i].changed = mChildInfosBefore[i].current;
+
+    for (i=0; i < mChildInfosAfterCount; i++) 
+      mChildInfosAfter[i].changed = mChildInfosAfter[i].current;
+
+    nscoord oldPos = pos;
+
+    ResizeChildTo(pos,
+                  mChildInfosBefore.get(), mChildInfosAfter.get(),
+                  mChildInfosBeforeCount, mChildInfosAfterCount, bounded);
+
+    State currentState = GetState();
+    bool supportsBefore = SupportsCollapseDirection(Before);
+    bool supportsAfter = SupportsCollapseDirection(After);
+
+    const bool isRTL = mOuter->StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
+    bool pastEnd = oldPos > 0 && oldPos > pos;
+    bool pastBegin = oldPos < 0 && oldPos < pos;
+    if (isRTL) {
+      // Swap the boundary checks in RTL mode
+      bool tmp = pastEnd;
+      pastEnd = pastBegin;
+      pastBegin = tmp;
+    }
+    const bool isCollapsedBefore = pastBegin && supportsBefore;
+    const bool isCollapsedAfter = pastEnd && supportsAfter;
+
+    // if we are in a collapsed position
+    if (isCollapsedBefore || isCollapsedAfter)
+    {
+      // and we are not collapsed then collapse
+      if (currentState == Dragging) {
+        if (pastEnd)
+        {
+          //printf("Collapse right\n");
+          if (supportsAfter) 
+          {
+            nsCOMPtr<nsIContent> outer = mOuter->mContent;
+            outer->SetAttr(kNameSpaceID_None, nsGkAtoms::substate,
+                           NS_LITERAL_STRING("after"),
+                           true);
+            outer->SetAttr(kNameSpaceID_None, nsGkAtoms::state,
+                           NS_LITERAL_STRING("collapsed"),
+                           true);
+          }
+
+        } else if (pastBegin)
+        {
+          //printf("Collapse left\n");
+          if (supportsBefore)
+          {
+            nsCOMPtr<nsIContent> outer = mOuter->mContent;
+            outer->SetAttr(kNameSpaceID_None, nsGkAtoms::substate,
+                           NS_LITERAL_STRING("before"),
+                           true);
+            outer->SetAttr(kNameSpaceID_None, nsGkAtoms::state,
+                           NS_LITERAL_STRING("collapsed"),
+                           true);
+          }
+        }
+      }
+    } else {
+      // if we are not in a collapsed position and we are not dragging make sure
+      // we are dragging.
+      if (currentState != Dragging)
+        mOuter->mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::state, NS_LITERAL_STRING("dragging"), true);
+      AdjustChildren(aPresContext);
+    }
+
+    mDidDrag = true;
+  }
+}
+
+void
+nsSplitterFrameInner::AddListener()
+{
+  mOuter->GetContent()->
+    AddEventListener(NS_LITERAL_STRING("mouseup"), this, false, false);
+  mOuter->GetContent()->
+    AddEventListener(NS_LITERAL_STRING("mousedown"), this, false, false);
+  mOuter->GetContent()->
+    AddEventListener(NS_LITERAL_STRING("mousemove"), this, false, false);
+  mOuter->GetContent()->
+    AddEventListener(NS_LITERAL_STRING("mouseout"), this, false, false);
+}
+
+void
+nsSplitterFrameInner::RemoveListener()
+{
+  ENSURE_TRUE(mOuter);
+  mOuter->GetContent()->
+    RemoveEventListener(NS_LITERAL_STRING("mouseup"), this, false);
+  mOuter->GetContent()->
+    RemoveEventListener(NS_LITERAL_STRING("mousedown"), this, false);
+  mOuter->GetContent()->
+    RemoveEventListener(NS_LITERAL_STRING("mousemove"), this, false);
+  mOuter->GetContent()->
+    RemoveEventListener(NS_LITERAL_STRING("mouseout"), this, false);
+}
+
+nsresult
+nsSplitterFrameInner::HandleEvent(nsIDOMEvent* aEvent)
+{
+  nsAutoString eventType;
+  aEvent->GetType(eventType);
+  if (eventType.EqualsLiteral("mouseup"))
+    return MouseUp(aEvent);
+  if (eventType.EqualsLiteral("mousedown"))
+    return MouseDown(aEvent);
+  if (eventType.EqualsLiteral("mousemove") ||
+      eventType.EqualsLiteral("mouseout"))
+    return MouseMove(aEvent);
+
+  NS_ABORT();
+  return NS_OK;
+}
+
+nsresult
+nsSplitterFrameInner::MouseUp(nsIDOMEvent* aMouseEvent)
+{  
+  NS_ENSURE_TRUE(mOuter, NS_OK);
+  mPressed = false;
+
+  nsIPresShell::SetCapturingContent(nullptr, 0);
+
+  return NS_OK;
+}
+
+nsresult
+nsSplitterFrameInner::MouseDown(nsIDOMEvent* aMouseEvent)
+{  
+  NS_ENSURE_TRUE(mOuter, NS_OK);
+  nsCOMPtr<nsIDOMMouseEvent> mouseEvent(do_QueryInterface(aMouseEvent));
+  if (!mouseEvent)
+    return NS_OK;
+
+  int16_t button = 0;
+  mouseEvent->GetButton(&button);
+
+  // only if left button
+  if (button != 0)
+     return NS_OK;
+
+  if (mOuter->GetContent()->
+        AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                    nsGkAtoms::_true, eCaseMatters))
+    return NS_OK;
+
+  mParentBox = nsBox::GetParentXULBox(mOuter);
+  if (!mParentBox)
+    return NS_OK;
+
+  // get our index
+  nsPresContext* outerPresContext = mOuter->PresContext();
+  const nsFrameList& siblingList(mParentBox->PrincipalChildList());
+  int32_t childIndex = siblingList.IndexOf(mOuter);
+  // if it's 0 (or not found) then stop right here.
+  // It might be not found if we're not in the parent's primary frame list.
+  if (childIndex <= 0)
+    return NS_OK;
+
+  int32_t childCount = siblingList.GetLength();
+  // if it's the last index then we need to allow for resizeafter="grow"
+  if (childIndex == childCount - 1 && GetResizeAfter() != Grow)
+    return NS_OK;
+
+  nsRenderingContext rc(
+    outerPresContext->PresShell()->CreateReferenceRenderingContext());
+  nsBoxLayoutState state(outerPresContext, &rc);
+  mCurrentPos = 0;
+  mPressed = true;
+
+  mDidDrag = false;
+
+  EnsureOrient();
+  bool isHorizontal = !mOuter->IsXULHorizontal();
+  
+  ResizeType resizeBefore = GetResizeBefore();
+  ResizeType resizeAfter  = GetResizeAfter();
+
+  mChildInfosBefore = MakeUnique<nsSplitterInfo[]>(childCount);
+  mChildInfosAfter  = MakeUnique<nsSplitterInfo[]>(childCount);
+
+  // create info 2 lists. One of the children before us and one after.
+  int32_t count = 0;
+  mChildInfosBeforeCount = 0;
+  mChildInfosAfterCount = 0;
+
+  nsIFrame* childBox = nsBox::GetChildXULBox(mParentBox);
+
+  while (nullptr != childBox) 
+  { 
+    nsIContent* content = childBox->GetContent();
+    nsIDocument* doc = content->OwnerDoc();
+    int32_t dummy;
+    nsIAtom* atom = doc->BindingManager()->ResolveTag(content, &dummy);
+
+    // skip over any splitters
+    if (atom != nsGkAtoms::splitter) { 
+        nsSize prefSize = childBox->GetXULPrefSize(state);
+        nsSize minSize = childBox->GetXULMinSize(state);
+        nsSize maxSize = nsBox::BoundsCheckMinMax(minSize, childBox->GetXULMaxSize(state));
+        prefSize = nsBox::BoundsCheck(minSize, prefSize, maxSize);
+
+        mOuter->AddMargin(childBox, minSize);
+        mOuter->AddMargin(childBox, prefSize);
+        mOuter->AddMargin(childBox, maxSize);
+
+        nscoord flex = childBox->GetXULFlex();
+
+        nsMargin margin(0,0,0,0);
+        childBox->GetXULMargin(margin);
+        nsRect r(childBox->GetRect());
+        r.Inflate(margin);
+
+        // We need to check for hidden attribute too, since treecols with
+        // the hidden="true" attribute are not really hidden, just collapsed
+        if (!content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::fixed,
+                                  nsGkAtoms::_true, eCaseMatters) &&
+            !content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::hidden,
+                                  nsGkAtoms::_true, eCaseMatters)) {
+            if (count < childIndex && (resizeBefore != Flex || flex > 0)) {
+                mChildInfosBefore[mChildInfosBeforeCount].childElem = content;
+                mChildInfosBefore[mChildInfosBeforeCount].min     = isHorizontal ? minSize.width : minSize.height;
+                mChildInfosBefore[mChildInfosBeforeCount].max     = isHorizontal ? maxSize.width : maxSize.height;
+                mChildInfosBefore[mChildInfosBeforeCount].current = isHorizontal ? r.width : r.height;
+                mChildInfosBefore[mChildInfosBeforeCount].flex    = flex;
+                mChildInfosBefore[mChildInfosBeforeCount].index   = count;
+                mChildInfosBefore[mChildInfosBeforeCount].changed = mChildInfosBefore[mChildInfosBeforeCount].current;
+                mChildInfosBeforeCount++;
+            } else if (count > childIndex && (resizeAfter != Flex || flex > 0)) {
+                mChildInfosAfter[mChildInfosAfterCount].childElem = content;
+                mChildInfosAfter[mChildInfosAfterCount].min     = isHorizontal ? minSize.width : minSize.height;
+                mChildInfosAfter[mChildInfosAfterCount].max     = isHorizontal ? maxSize.width : maxSize.height;
+                mChildInfosAfter[mChildInfosAfterCount].current = isHorizontal ? r.width : r.height;
+                mChildInfosAfter[mChildInfosAfterCount].flex    = flex;
+                mChildInfosAfter[mChildInfosAfterCount].index   = count;
+                mChildInfosAfter[mChildInfosAfterCount].changed = mChildInfosAfter[mChildInfosAfterCount].current;
+                mChildInfosAfterCount++;
+            }
+        } 
+    }
+    
+    childBox = nsBox::GetNextXULBox(childBox);
+    count++;
+  }
+
+  if (!mParentBox->IsXULNormalDirection()) {
+    // The before array is really the after array, and the order needs to be reversed.
+    // First reverse both arrays.
+    Reverse(mChildInfosBefore, mChildInfosBeforeCount);
+    Reverse(mChildInfosAfter, mChildInfosAfterCount);
+
+    // Now swap the two arrays.
+    Swap(mChildInfosBeforeCount, mChildInfosAfterCount);
+    Swap(mChildInfosBefore, mChildInfosAfter);
+  }
+
+  // if resizebefore is not Farthest, reverse the list because the first child
+  // in the list is the farthest, and we want the first child to be the closest.
+  if (resizeBefore != Farthest)
+     Reverse(mChildInfosBefore, mChildInfosBeforeCount);
+
+  // if the resizeafter is the Farthest we must reverse the list because the first child in the list
+  // is the closest we want the first child to be the Farthest.
+  if (resizeAfter == Farthest)
+     Reverse(mChildInfosAfter, mChildInfosAfterCount);
+
+  // grow only applys to the children after. If grow is set then no space should be taken out of any children after
+  // us. To do this we just set the size of that list to be 0.
+  if (resizeAfter == Grow)
+     mChildInfosAfterCount = 0;
+
+  int32_t c;
+  nsPoint pt = nsLayoutUtils::GetDOMEventCoordinatesRelativeTo(mouseEvent->AsEvent(),
+                                                               mParentBox);
+  if (isHorizontal) {
+     c = pt.x;
+     mSplitterPos = mOuter->mRect.x;
+  } else {
+     c = pt.y;
+     mSplitterPos = mOuter->mRect.y;
+  }
+
+  mDragStart = c;
+
+  //printf("Pressed mDragStart=%d\n",mDragStart);
+
+  nsIPresShell::SetCapturingContent(mOuter->GetContent(), CAPTURE_IGNOREALLOWED);
+
+  return NS_OK;
+}
+
+nsresult
+nsSplitterFrameInner::MouseMove(nsIDOMEvent* aMouseEvent)
+{  
+  NS_ENSURE_TRUE(mOuter, NS_OK);
+  if (!mPressed)
+    return NS_OK;
+
+  if (mDragging)
+    return NS_OK;
+
+  nsCOMPtr<nsIDOMEventListener> kungfuDeathGrip(this);
+  mOuter->mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::state,
+                            NS_LITERAL_STRING("dragging"), true);
+
+  RemoveListener();
+  mDragging = true;
+
+  return NS_OK;
+}
+
+void
+nsSplitterFrameInner::Reverse(UniquePtr<nsSplitterInfo[]>& aChildInfos, int32_t aCount)
+{
+    UniquePtr<nsSplitterInfo[]> infos(new nsSplitterInfo[aCount]);
+
+    for (int i=0; i < aCount; i++)
+       infos[i] = aChildInfos[aCount - 1 - i];
+
+    aChildInfos = Move(infos);
+}
+
+bool
+nsSplitterFrameInner::SupportsCollapseDirection
+(
+  nsSplitterFrameInner::CollapseDirection aDirection
+)
+{
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::before, &nsGkAtoms::after, &nsGkAtoms::both, nullptr};
+
+  switch (mOuter->mContent->FindAttrValueIn(kNameSpaceID_None,
+                                            nsGkAtoms::collapse,
+                                            strings, eCaseMatters)) {
+    case 0:
+      return (aDirection == Before);
+    case 1:
+      return (aDirection == After);
+    case 2:
+      return true;
+  }
+
+  return false;
+}
+
+void
+nsSplitterFrameInner::UpdateState()
+{
+  // State Transitions:
+  //   Open            -> Dragging
+  //   Open            -> CollapsedBefore
+  //   Open            -> CollapsedAfter
+  //   CollapsedBefore -> Open
+  //   CollapsedBefore -> Dragging
+  //   CollapsedAfter  -> Open
+  //   CollapsedAfter  -> Dragging
+  //   Dragging        -> Open
+  //   Dragging        -> CollapsedBefore (auto collapse)
+  //   Dragging        -> CollapsedAfter (auto collapse)
+
+  State newState = GetState(); 
+
+  if (newState == mState) {
+    // No change.
+    return;
+  }
+
+  if ((SupportsCollapseDirection(Before) || SupportsCollapseDirection(After)) &&
+      mOuter->GetParent()->IsXULBoxFrame()) {
+    // Find the splitter's immediate sibling.
+    nsIFrame* splitterSibling;
+    if (newState == CollapsedBefore || mState == CollapsedBefore) {
+      splitterSibling = mOuter->GetPrevSibling();
+    } else {
+      splitterSibling = mOuter->GetNextSibling();
+    }
+
+    if (splitterSibling) {
+      nsCOMPtr<nsIContent> sibling = splitterSibling->GetContent();
+      if (sibling) {
+        if (mState == CollapsedBefore || mState == CollapsedAfter) {
+          // CollapsedBefore -> Open
+          // CollapsedBefore -> Dragging
+          // CollapsedAfter -> Open
+          // CollapsedAfter -> Dragging
+          nsContentUtils::AddScriptRunner(
+            new nsUnsetAttrRunnable(sibling, nsGkAtoms::collapsed));
+        } else if ((mState == Open || mState == Dragging)
+                   && (newState == CollapsedBefore ||
+                       newState == CollapsedAfter)) {
+          // Open -> CollapsedBefore / CollapsedAfter
+          // Dragging -> CollapsedBefore / CollapsedAfter
+          nsContentUtils::AddScriptRunner(
+            new nsSetAttrRunnable(sibling, nsGkAtoms::collapsed,
+                                  NS_LITERAL_STRING("true")));
+        }
+      }
+    }
+  }
+  mState = newState;
+}
+
+void
+nsSplitterFrameInner::EnsureOrient()
+{
+  bool isHorizontal = !(mParentBox->GetStateBits() & NS_STATE_IS_HORIZONTAL);
+  if (isHorizontal)
+    mOuter->mState |= NS_STATE_IS_HORIZONTAL;
+  else
+    mOuter->mState &= ~NS_STATE_IS_HORIZONTAL;
+}
+
+void
+nsSplitterFrameInner::AdjustChildren(nsPresContext* aPresContext)
+{
+  EnsureOrient();
+  bool isHorizontal = !mOuter->IsXULHorizontal();
+
+  AdjustChildren(aPresContext, mChildInfosBefore.get(),
+                 mChildInfosBeforeCount, isHorizontal);
+  AdjustChildren(aPresContext, mChildInfosAfter.get(),
+                 mChildInfosAfterCount, isHorizontal);
+}
+
+static nsIFrame* GetChildBoxForContent(nsIFrame* aParentBox, nsIContent* aContent)
+{
+  nsIFrame* childBox = nsBox::GetChildXULBox(aParentBox);
+
+  while (nullptr != childBox) {
+    if (childBox->GetContent() == aContent) {
+      return childBox;
+    }
+    childBox = nsBox::GetNextXULBox(childBox);
+  }
+  return nullptr;
+}
+
+void
+nsSplitterFrameInner::AdjustChildren(nsPresContext* aPresContext, nsSplitterInfo* aChildInfos, int32_t aCount, bool aIsHorizontal)
+{
+  ///printf("------- AdjustChildren------\n");
+
+  nsBoxLayoutState state(aPresContext);
+
+  nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
+
+  // first set all the widths.
+  nsIFrame* child =  nsBox::GetChildXULBox(mOuter);
+  while(child)
+  {
+    SetPreferredSize(state, child, onePixel, aIsHorizontal, nullptr);
+    child = nsBox::GetNextXULBox(child);
+  }
+
+  // now set our changed widths.
+  for (int i=0; i < aCount; i++) 
+  {
+    nscoord   pref       = aChildInfos[i].changed;
+    nsIFrame* childBox     = GetChildBoxForContent(mParentBox, aChildInfos[i].childElem);
+
+    if (childBox) {
+      SetPreferredSize(state, childBox, onePixel, aIsHorizontal, &pref);
+    }
+  }
+}
+
+void
+nsSplitterFrameInner::SetPreferredSize(nsBoxLayoutState& aState, nsIFrame* aChildBox, nscoord aOnePixel, bool aIsHorizontal, nscoord* aSize)
+{
+  nsRect rect(aChildBox->GetRect());
+  nscoord pref = 0;
+
+  if (!aSize)
+  {
+    if (aIsHorizontal) 
+      pref = rect.width;
+    else
+      pref = rect.height;
+  } else {
+    pref = *aSize;
+  }
+
+  nsMargin margin(0,0,0,0);
+  aChildBox->GetXULMargin(margin);
+
+  nsCOMPtr<nsIAtom> attribute;
+
+  if (aIsHorizontal) {
+    pref -= (margin.left + margin.right);
+    attribute = nsGkAtoms::width;
+  } else {
+    pref -= (margin.top + margin.bottom);
+    attribute = nsGkAtoms::height;
+  }
+
+  nsIContent* content = aChildBox->GetContent();
+
+  // set its preferred size.
+  nsAutoString prefValue;
+  prefValue.AppendInt(pref/aOnePixel);
+  if (content->AttrValueIs(kNameSpaceID_None, attribute,
+                           prefValue, eCaseMatters))
+     return;
+
+  nsWeakFrame weakBox(aChildBox);
+  content->SetAttr(kNameSpaceID_None, attribute, prefValue, true);
+  ENSURE_TRUE(weakBox.IsAlive());
+  aState.PresShell()->FrameNeedsReflow(aChildBox, nsIPresShell::eStyleChange,
+                                       NS_FRAME_IS_DIRTY);
+}
+
+
+void 
+nsSplitterFrameInner::AddRemoveSpace(nscoord aDiff,
+                                    nsSplitterInfo* aChildInfos,
+                                    int32_t aCount,
+                                    int32_t& aSpaceLeft)
+{
+  aSpaceLeft = 0;
+
+  for (int i=0; i < aCount; i++) {   
+    nscoord min    = aChildInfos[i].min;
+    nscoord max    = aChildInfos[i].max;
+    nscoord& c     = aChildInfos[i].changed;
+
+    // figure our how much space to add or remove
+    if (c + aDiff < min) {
+      aDiff += (c - min);
+      c = min;
+    } else if (c + aDiff > max) {
+      aDiff -= (max - c);
+      c = max;
+    } else {
+      c += aDiff;
+      aDiff = 0;
+    }
+
+    // there is not space left? We are done
+    if (aDiff == 0)
+      break;
+  }
+
+  aSpaceLeft = aDiff;
+}
+
+/**
+ * Ok if we want to resize a child we will know the actual size in pixels we want it to be.
+ * This is not the preferred size. But they only way we can change a child is my manipulating its
+ * preferred size. So give the actual pixel size this return method will return figure out the preferred
+ * size and set it.
+ */
+
+void
+nsSplitterFrameInner::ResizeChildTo(nscoord& aDiff,
+                                    nsSplitterInfo* aChildrenBeforeInfos,
+                                    nsSplitterInfo* aChildrenAfterInfos,
+                                    int32_t aChildrenBeforeCount,
+                                    int32_t aChildrenAfterCount,
+                                    bool aBounded)
+{
+  nscoord spaceLeft;
+  AddRemoveSpace(aDiff, aChildrenBeforeInfos,aChildrenBeforeCount,spaceLeft);
+
+  // if there is any space left over remove it from the dif we were originally given
+  aDiff -= spaceLeft;
+  AddRemoveSpace(-aDiff, aChildrenAfterInfos,aChildrenAfterCount,spaceLeft);
+
+  if (spaceLeft != 0) {
+    if (aBounded) {
+       aDiff += spaceLeft;
+       AddRemoveSpace(spaceLeft, aChildrenBeforeInfos,aChildrenBeforeCount,spaceLeft);
+    }
+  }
+}
diff --git a/layout/xul/nsSplitterFrame.h b/layout/xul/nsSplitterFrame.h
new file mode 100644
index 0000000000..df8872255e
--- /dev/null
+++ b/layout/xul/nsSplitterFrame.h
@@ -0,0 +1,83 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// nsSplitterFrame
+//
+
+#ifndef nsSplitterFrame_h__
+#define nsSplitterFrame_h__
+
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+class nsSplitterFrameInner;
+
+nsIFrame* NS_NewSplitterFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+class nsSplitterFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  explicit nsSplitterFrame(nsStyleContext* aContext);
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override {
+    return MakeFrameName(NS_LITERAL_STRING("SplitterFrame"), aResult);
+  }
+#endif
+
+  // nsIFrame overrides
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual nsresult GetCursor(const nsPoint&    aPoint,
+                             nsIFrame::Cursor& aCursor) override;
+
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aBoxLayoutState) override;
+
+  NS_IMETHOD HandlePress(nsPresContext* aPresContext,
+                         mozilla::WidgetGUIEvent* aEvent,
+                         nsEventStatus* aEventStatus) override;
+
+  NS_IMETHOD HandleMultiplePress(nsPresContext* aPresContext,
+                                 mozilla::WidgetGUIEvent* aEvent,
+                                 nsEventStatus* aEventStatus,
+                                 bool aControlHeld) override;
+
+  NS_IMETHOD HandleDrag(nsPresContext* aPresContext,
+                        mozilla::WidgetGUIEvent* aEvent,
+                        nsEventStatus* aEventStatus) override;
+
+  NS_IMETHOD HandleRelease(nsPresContext* aPresContext,
+                           mozilla::WidgetGUIEvent* aEvent,
+                           nsEventStatus* aEventStatus) override;
+
+  virtual nsresult HandleEvent(nsPresContext* aPresContext,
+                               mozilla::WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+
+  virtual void GetInitialOrientation(bool& aIsHorizontal) override; 
+
+private:
+
+  friend class nsSplitterFrameInner;
+  nsSplitterFrameInner* mInner;
+
+}; // class nsSplitterFrame
+
+#endif
diff --git a/layout/xul/nsSprocketLayout.cpp b/layout/xul/nsSprocketLayout.cpp
new file mode 100644
index 0000000000..8ce73566ba
--- /dev/null
+++ b/layout/xul/nsSprocketLayout.cpp
@@ -0,0 +1,1652 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsBoxLayoutState.h"
+#include "nsSprocketLayout.h"
+#include "nsPresContext.h"
+#include "nsCOMPtr.h"
+#include "nsIContent.h"
+#include "nsIPresShell.h"
+#include "nsContainerFrame.h"
+#include "nsBoxFrame.h"
+#include "StackArena.h"
+#include "mozilla/Likely.h"
+#include <algorithm>
+
+nsBoxLayout* nsSprocketLayout::gInstance = nullptr;
+
+//#define DEBUG_GROW
+
+#define DEBUG_SPRING_SIZE 8
+#define DEBUG_BORDER_SIZE 2
+#define COIL_SIZE 8
+
+
+nsresult
+NS_NewSprocketLayout(nsCOMPtr<nsBoxLayout>& aNewLayout)
+{
+  if (!nsSprocketLayout::gInstance) {
+    nsSprocketLayout::gInstance = new nsSprocketLayout();
+    NS_IF_ADDREF(nsSprocketLayout::gInstance);
+  }
+  // we have not instance variables so just return our static one.
+  aNewLayout = nsSprocketLayout::gInstance;
+  return NS_OK;
+} 
+
+/*static*/ void
+nsSprocketLayout::Shutdown()
+{
+  NS_IF_RELEASE(gInstance);
+}
+
+nsSprocketLayout::nsSprocketLayout()
+{
+}
+
+bool 
+nsSprocketLayout::IsXULHorizontal(nsIFrame* aBox)
+{
+   return (aBox->GetStateBits() & NS_STATE_IS_HORIZONTAL) != 0;
+}
+
+void
+nsSprocketLayout::GetFrameState(nsIFrame* aBox, nsFrameState& aState)
+{
+   aState = aBox->GetStateBits();
+}
+
+static uint8_t
+GetFrameDirection(nsIFrame* aBox)
+{
+   return aBox->StyleVisibility()->mDirection;
+}
+
+static void
+HandleBoxPack(nsIFrame* aBox, const nsFrameState& aFrameState, nscoord& aX, nscoord& aY, 
+              const nsRect& aOriginalRect, const nsRect& aClientRect)
+{
+  // In the normal direction we lay out our kids in the positive direction (e.g., |x| will get
+  // bigger for a horizontal box, and |y| will get bigger for a vertical box).  In the reverse
+  // direction, the opposite is true.  We'll be laying out each child at a smaller |x| or
+  // |y|.
+  uint8_t frameDirection = GetFrameDirection(aBox);
+
+  if (aFrameState & NS_STATE_IS_HORIZONTAL) {
+    if (aFrameState & NS_STATE_IS_DIRECTION_NORMAL) {
+      // The normal direction. |x| increases as we move through our children.
+      aX = aClientRect.x;
+    }
+    else {
+      // The reverse direction. |x| decreases as we move through our children.
+      aX = aClientRect.x + aOriginalRect.width;
+    }
+    // |y| is always in the normal direction in horizontal boxes
+    aY = aClientRect.y;    
+  }
+  else {
+    // take direction property into account for |x| in vertical boxes
+    if (frameDirection == NS_STYLE_DIRECTION_LTR) {
+      // The normal direction. |x| increases as we move through our children.
+      aX = aClientRect.x;
+    }
+    else {
+      // The reverse direction. |x| decreases as we move through our children.
+      aX = aClientRect.x + aOriginalRect.width;
+    }
+    if (aFrameState & NS_STATE_IS_DIRECTION_NORMAL) {
+      // The normal direction. |y| increases as we move through our children.
+      aY = aClientRect.y;
+    }
+    else {
+      // The reverse direction. |y| decreases as we move through our children.
+      aY = aClientRect.y + aOriginalRect.height;
+    }
+  }
+
+  // Get our pack/alignment information.
+  nsIFrame::Halignment halign = aBox->GetXULHAlign();
+  nsIFrame::Valignment valign = aBox->GetXULVAlign();
+
+  // The following code handles box PACKING.  Packing comes into play in the case where the computed size for 
+  // all of our children (now stored in our client rect) is smaller than the size available for
+  // the box (stored in |aOriginalRect|).  
+  // 
+  // Here we adjust our |x| and |y| variables accordingly so that we start at the beginning,
+  // middle, or end of the box.
+  //
+  // XXXdwh JUSTIFY needs to be implemented!
+  if (aFrameState & NS_STATE_IS_HORIZONTAL) {
+    switch(halign) {
+      case nsBoxFrame::hAlign_Left:
+        break; // Nothing to do.  The default initialized us properly.
+
+      case nsBoxFrame::hAlign_Center:
+        if (aFrameState & NS_STATE_IS_DIRECTION_NORMAL)
+          aX += (aOriginalRect.width - aClientRect.width)/2;
+        else 
+          aX -= (aOriginalRect.width - aClientRect.width)/2;
+        break;
+
+      case nsBoxFrame::hAlign_Right:
+        if (aFrameState & NS_STATE_IS_DIRECTION_NORMAL)
+          aX += (aOriginalRect.width - aClientRect.width);
+        else
+          aX -= (aOriginalRect.width - aClientRect.width);
+        break; // Nothing to do for the reverse dir.  The default initialized us properly.
+    }
+  } else {
+    switch(valign) {
+      case nsBoxFrame::vAlign_Top:
+      case nsBoxFrame::vAlign_BaseLine: // This value is technically impossible to specify for pack.
+        break;  // Don't do anything.  We were initialized correctly.
+
+      case nsBoxFrame::vAlign_Middle:
+        if (aFrameState & NS_STATE_IS_DIRECTION_NORMAL)
+          aY += (aOriginalRect.height - aClientRect.height)/2;
+        else
+          aY -= (aOriginalRect.height - aClientRect.height)/2;
+        break;
+
+      case nsBoxFrame::vAlign_Bottom:
+        if (aFrameState & NS_STATE_IS_DIRECTION_NORMAL)
+          aY += (aOriginalRect.height - aClientRect.height);
+        else
+          aY -= (aOriginalRect.height - aClientRect.height);
+        break;
+    }
+  }
+}
+
+NS_IMETHODIMP
+nsSprocketLayout::XULLayout(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  // See if we are collapsed. If we are, then simply iterate over all our
+  // children and give them a rect of 0 width and height.
+  if (aBox->IsXULCollapsed()) {
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+    while(child) 
+    {
+      nsBoxFrame::LayoutChildAt(aState, child, nsRect(0,0,0,0));  
+      child = nsBox::GetNextXULBox(child);
+    }
+    return NS_OK;
+  }
+
+  nsBoxLayoutState::AutoReflowDepth depth(aState);
+  mozilla::AutoStackArena arena;
+
+  // ----- figure out our size ----------
+  const nsSize originalSize = aBox->GetSize();
+
+  // -- make sure we remove our border and padding  ----
+  nsRect clientRect;
+  aBox->GetXULClientRect(clientRect);
+
+  // |originalClientRect| represents the rect of the entire box (excluding borders
+  // and padding).  We store it here because we're going to use |clientRect| to hold
+  // the required size for all our kids.  As an example, consider an hbox with a
+  // specified width of 300.  If the kids total only 150 pixels of width, then
+  // we have 150 pixels left over.  |clientRect| is going to hold a width of 150 and
+  // is going to be adjusted based off the value of the PACK property.  If flexible
+  // objects are in the box, then the two rects will match.
+  nsRect originalClientRect(clientRect);
+
+  // The frame state contains cached knowledge about our box, such as our orientation
+  // and direction.
+  nsFrameState frameState = nsFrameState(0);
+  GetFrameState(aBox, frameState);
+
+  // Build a list of our children's desired sizes and computed sizes
+  nsBoxSize*         boxSizes = nullptr;
+  nsComputedBoxSize* computedBoxSizes = nullptr;
+
+  nscoord min = 0;
+  nscoord max = 0;
+  int32_t flexes = 0;
+  PopulateBoxSizes(aBox, aState, boxSizes, min, max, flexes);
+  
+  // The |size| variable will hold the total size of children along the axis of
+  // the box.  Continuing with the example begun in the comment above, size would
+  // be 150 pixels.
+  nscoord size = clientRect.width;
+  if (!IsXULHorizontal(aBox))
+    size = clientRect.height;
+  ComputeChildSizes(aBox, aState, size, boxSizes, computedBoxSizes);
+
+  // After the call to ComputeChildSizes, the |size| variable contains the
+  // total required size of all the children.  We adjust our clientRect in the
+  // appropriate dimension to match this size.  In our example, we now assign
+  // 150 pixels into the clientRect.width.
+  //
+  // The variables |min| and |max| hold the minimum required size box must be 
+  // in the OPPOSITE orientation, e.g., for a horizontal box, |min| is the minimum
+  // height we require to enclose our children, and |max| is the maximum height
+  // required to enclose our children.
+  if (IsXULHorizontal(aBox)) {
+    clientRect.width = size;
+    if (clientRect.height < min)
+      clientRect.height = min;
+
+    if (frameState & NS_STATE_AUTO_STRETCH) {
+      if (clientRect.height > max)
+        clientRect.height = max;
+    }
+  } else {
+    clientRect.height = size;
+    if (clientRect.width < min)
+      clientRect.width = min;
+
+    if (frameState & NS_STATE_AUTO_STRETCH) {
+      if (clientRect.width > max)
+        clientRect.width = max;
+    }
+  }
+
+  // With the sizes computed, now it's time to lay out our children.
+  bool finished;
+  nscoord passes = 0;
+
+  // We flow children at their preferred locations (along with the appropriate computed flex).  
+  // After we flow a child, it is possible that the child will change its size.  If/when this happens,
+  // we have to do another pass.  Typically only 2 passes are required, but the code is prepared to
+  // do as many passes as are necessary to achieve equilibrium.
+  nscoord x = 0;
+  nscoord y = 0;
+  nscoord origX = 0;
+  nscoord origY = 0;
+
+  // |childResized| lets us know if a child changed its size after we attempted to lay it out at
+  // the specified size.  If this happens, we usually have to do another pass.
+  bool childResized = false;
+
+  // |passes| stores our number of passes.  If for any reason we end up doing more than, say, 10
+  // passes, we assert to indicate that something is seriously screwed up.
+  passes = 0;
+  do 
+  { 
+#ifdef DEBUG_REFLOW
+    if (passes > 0) {
+      AddIndents();
+      printf("ChildResized doing pass: %d\n", passes);
+    }
+#endif 
+
+    // Always assume that we're done.  This will change if, for example, children don't stay
+    // the same size after being flowed.
+    finished = true;
+
+    // Handle box packing.
+    HandleBoxPack(aBox, frameState, x, y, originalClientRect, clientRect);
+
+    // Now that packing is taken care of we set up a few additional
+    // tracking variables.
+    origX = x;
+    origY = y;
+
+    // Now we iterate over our box children and our box size lists in 
+    // parallel.  For each child, we look at its sizes and figure out
+    // where to place it.
+    nsComputedBoxSize* childComputedBoxSize = computedBoxSizes;
+    nsBoxSize* childBoxSize                 = boxSizes;
+
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+
+    int32_t count = 0;
+    while (child || (childBoxSize && childBoxSize->bogus))
+    { 
+      // If for some reason, our lists are not the same length, we guard
+      // by bailing out of the loop.
+      if (childBoxSize == nullptr) {
+        NS_NOTREACHED("Lists not the same length.");
+        break;
+      }
+        
+      nscoord width = clientRect.width;
+      nscoord height = clientRect.height;
+
+      if (!childBoxSize->bogus) {
+        // We have a valid box size entry.  This entry already contains information about our
+        // sizes along the axis of the box (e.g., widths in a horizontal box).  If our default
+        // ALIGN is not stretch, however, then we also need to know the child's size along the
+        // opposite axis.
+        if (!(frameState & NS_STATE_AUTO_STRETCH)) {
+           nsSize prefSize = child->GetXULPrefSize(aState);
+           nsSize minSize = child->GetXULMinSize(aState);
+           nsSize maxSize = child->GetXULMaxSize(aState);
+           prefSize = nsBox::BoundsCheck(minSize, prefSize, maxSize);
+       
+           AddMargin(child, prefSize);
+           width = std::min(prefSize.width, originalClientRect.width);
+           height = std::min(prefSize.height, originalClientRect.height);
+        }
+      }
+
+      // Obtain the computed size along the axis of the box for this child from the computedBoxSize entry.  
+      // We store the result in |width| for horizontal boxes and |height| for vertical boxes.
+      if (frameState & NS_STATE_IS_HORIZONTAL)
+        width = childComputedBoxSize->size;
+      else
+        height = childComputedBoxSize->size;
+      
+      // Adjust our x/y for the left/right spacing.
+      if (frameState & NS_STATE_IS_HORIZONTAL) {
+        if (frameState & NS_STATE_IS_DIRECTION_NORMAL)
+          x += (childBoxSize->left);
+        else
+          x -= (childBoxSize->right);
+      } else {
+        if (frameState & NS_STATE_IS_DIRECTION_NORMAL)
+          y += (childBoxSize->left);
+        else
+          y -= (childBoxSize->right);
+      }
+
+      // Now we build a child rect.
+      nscoord rectX = x;
+      nscoord rectY = y;
+      if (!(frameState & NS_STATE_IS_DIRECTION_NORMAL)) {
+        if (frameState & NS_STATE_IS_HORIZONTAL)
+          rectX -= width;
+        else
+          rectY -= height;
+      }
+
+      // We now create an accurate child rect based off our computed size information.
+      nsRect childRect(rectX, rectY, width, height);
+
+      // Sanity check against our clientRect.  It is possible that a child specified
+      // a size that is too large to fit.  If that happens, then we have to grow
+      // our client rect.  Remember, clientRect is not the total rect of the enclosing
+      // box.  It currently holds our perception of how big the children needed to
+      // be.
+      if (childRect.width > clientRect.width)
+        clientRect.width = childRect.width;
+
+      if (childRect.height > clientRect.height)
+        clientRect.height = childRect.height;
+    
+      // Either |nextX| or |nextY| is updated by this function call, according
+      // to our axis.
+      nscoord nextX = x;
+      nscoord nextY = y;
+
+      ComputeChildsNextPosition(aBox, x, y, nextX, nextY, childRect);
+
+      // Now we further update our nextX/Y along our axis.
+      // We also set childRect.y/x along the opposite axis appropriately for a
+      // stretch alignment.  (Non-stretch alignment is handled below.)
+      if (frameState & NS_STATE_IS_HORIZONTAL) {
+        if (frameState & NS_STATE_IS_DIRECTION_NORMAL)
+          nextX += (childBoxSize->right);
+        else
+          nextX -= (childBoxSize->left);
+        childRect.y = originalClientRect.y;
+      }
+      else {
+        if (frameState & NS_STATE_IS_DIRECTION_NORMAL)
+          nextY += (childBoxSize->right);
+        else 
+          nextY -= (childBoxSize->left);
+        if (GetFrameDirection(aBox) == NS_STYLE_DIRECTION_LTR) {
+          childRect.x = originalClientRect.x;
+        } else {
+          // keep the right edge of the box the same
+          childRect.x = clientRect.x + originalClientRect.width - childRect.width;
+        }
+      }
+      
+      // If we encounter a completely bogus box size, we just leave this child completely
+      // alone and continue through the loop to the next child.
+      if (childBoxSize->bogus) 
+      {
+        childComputedBoxSize = childComputedBoxSize->next;
+        childBoxSize = childBoxSize->next;
+        count++;
+        x = nextX;
+        y = nextY;
+        continue;
+      }
+
+      nsMargin margin(0,0,0,0);
+
+      bool layout = true;
+
+      // Deflate the rect of our child by its margin.
+      child->GetXULMargin(margin);
+      childRect.Deflate(margin);
+      if (childRect.width < 0)
+        childRect.width = 0;
+      if (childRect.height < 0)
+        childRect.height = 0;
+
+      // Now we're trying to figure out if we have to lay out this child, i.e., to call
+      // the child's XULLayout method.
+      if (passes > 0) {
+        layout = false;
+      } else {
+        // Always perform layout if we are dirty or have dirty children
+        if (!NS_SUBTREE_DIRTY(child))
+          layout = false;
+      }
+
+      nsRect oldRect(child->GetRect());
+
+      // Non-stretch alignment will be handled in AlignChildren(), so don't
+      // change child out-of-axis positions yet.
+      if (!(frameState & NS_STATE_AUTO_STRETCH)) {
+        if (frameState & NS_STATE_IS_HORIZONTAL) {
+          childRect.y = oldRect.y;
+        } else {
+          childRect.x = oldRect.x;
+        }
+      }
+
+      // We computed a childRect.  Now we want to set the bounds of the child to be that rect.
+      // If our old rect is different, then we know our size changed and we cache that fact
+      // in the |sizeChanged| variable.
+
+      child->SetXULBounds(aState, childRect);
+      bool sizeChanged = (childRect.width != oldRect.width ||
+                            childRect.height != oldRect.height);
+
+      if (sizeChanged) {
+        // Our size is different.  Sanity check against our maximum allowed size to ensure
+        // we didn't exceed it.
+        nsSize minSize = child->GetXULMinSize(aState);
+        nsSize maxSize = child->GetXULMaxSize(aState);
+        maxSize = nsBox::BoundsCheckMinMax(minSize, maxSize);
+
+        // make sure the size is in our max size.
+        if (childRect.width > maxSize.width)
+          childRect.width = maxSize.width;
+
+        if (childRect.height > maxSize.height)
+          childRect.height = maxSize.height;
+           
+        // set it again
+        child->SetXULBounds(aState, childRect);
+      }
+
+      // If we already determined that layout was required or if our size has changed, then
+      // we make sure to call layout on the child, since its children may need to be shifted
+      // around as a result of the size change.
+      if (layout || sizeChanged)
+        child->XULLayout(aState);
+      
+      // If the child was a block or inline (e.g., HTML) it may have changed its rect *during* layout. 
+      // We have to check for this.
+      nsRect newChildRect(child->GetRect());
+
+      if (!newChildRect.IsEqualInterior(childRect)) {
+#ifdef DEBUG_GROW
+        child->XULDumpBox(stdout);
+        printf(" GREW from (%d,%d) -> (%d,%d)\n", childRect.width, childRect.height, newChildRect.width, newChildRect.height);
+#endif
+        newChildRect.Inflate(margin);
+        childRect.Inflate(margin);
+
+        // The child changed size during layout.  The ChildResized method handles this
+        // scenario.
+        ChildResized(aBox,
+                     aState, 
+                     child,
+                     childBoxSize,
+                     childComputedBoxSize,
+                     boxSizes, 
+                     computedBoxSizes, 
+                     childRect,
+                     newChildRect,
+                     clientRect,
+                     flexes,
+                     finished);
+
+        // We note that a child changed size, which means that another pass will be required.
+        childResized = true;
+
+        // Now that a child resized, it's entirely possible that OUR rect is too small.  Now we
+        // ensure that |originalClientRect| is grown to accommodate the size of |clientRect|.
+        if (clientRect.width > originalClientRect.width)
+          originalClientRect.width = clientRect.width;
+
+        if (clientRect.height > originalClientRect.height)
+          originalClientRect.height = clientRect.height;
+
+        if (!(frameState & NS_STATE_IS_DIRECTION_NORMAL)) {
+          // Our childRect had its XMost() or YMost() (depending on our layout
+          // direction), positioned at a certain point.  Ensure that the
+          // newChildRect satisfies the same constraint.  Note that this is
+          // just equivalent to adjusting the x/y by the difference in
+          // width/height between childRect and newChildRect.  So we don't need
+          // to reaccount for the left and right of the box layout state again.
+          if (frameState & NS_STATE_IS_HORIZONTAL)
+            newChildRect.x = childRect.XMost() - newChildRect.width;
+          else
+            newChildRect.y = childRect.YMost() - newChildRect.height;
+        }
+
+        if (!(frameState & NS_STATE_IS_HORIZONTAL)) {
+          if (GetFrameDirection(aBox) != NS_STYLE_DIRECTION_LTR) {
+            // keep the right edge the same
+            newChildRect.x = childRect.XMost() - newChildRect.width;
+          }
+        }
+
+        // If the child resized then recompute its position.
+        ComputeChildsNextPosition(aBox, x, y, nextX, nextY, newChildRect);
+
+        if (newChildRect.width >= margin.left + margin.right && newChildRect.height >= margin.top + margin.bottom) 
+          newChildRect.Deflate(margin);
+
+        if (childRect.width >= margin.left + margin.right && childRect.height >= margin.top + margin.bottom) 
+          childRect.Deflate(margin);
+            
+        child->SetXULBounds(aState, newChildRect);
+
+        // If we are the first box that changed size, then we don't need to do a second pass
+        if (count == 0)
+          finished = true;
+      }
+
+      // Now update our x/y finally.
+      x = nextX;
+      y = nextY;
+     
+      // Move to the next child.
+      childComputedBoxSize = childComputedBoxSize->next;
+      childBoxSize = childBoxSize->next;
+
+      child = nsBox::GetNextXULBox(child);
+      count++;
+    }
+
+    // Sanity-checking code to ensure we don't do an infinite # of passes.
+    passes++;
+    NS_ASSERTION(passes < 10, "A Box's child is constantly growing!!!!!");
+    if (passes > 10)
+      break;
+  } while (false == finished);
+
+  // Get rid of our size lists.
+  while(boxSizes)
+  {
+    nsBoxSize* toDelete = boxSizes;
+    boxSizes = boxSizes->next;
+    delete toDelete;
+  }
+
+  while(computedBoxSizes)
+  {
+    nsComputedBoxSize* toDelete = computedBoxSizes;
+    computedBoxSizes = computedBoxSizes->next;
+    delete toDelete;
+  }
+
+  if (childResized) {
+    // See if one of our children forced us to get bigger
+    nsRect tmpClientRect(originalClientRect);
+    nsMargin bp(0,0,0,0);
+    aBox->GetXULBorderAndPadding(bp);
+    tmpClientRect.Inflate(bp);
+
+    if (tmpClientRect.width > originalSize.width || tmpClientRect.height > originalSize.height)
+    {
+      // if it did reset our bounds.
+      nsRect bounds(aBox->GetRect());
+      if (tmpClientRect.width > originalSize.width)
+        bounds.width = tmpClientRect.width;
+
+      if (tmpClientRect.height > originalSize.height)
+        bounds.height = tmpClientRect.height;
+
+      aBox->SetXULBounds(aState, bounds);
+    }
+  }
+
+  // Because our size grew, we now have to readjust because of box packing.  Repack
+  // in order to update our x and y to the correct values.
+  HandleBoxPack(aBox, frameState, x, y, originalClientRect, clientRect);
+
+  // Compare against our original x and y and only worry about adjusting the children if
+  // we really did have to change the positions because of packing (typically for 'center'
+  // or 'end' pack values).
+  if (x != origX || y != origY) {
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+
+    // reposition all our children
+    while (child) 
+    {
+      nsRect childRect(child->GetRect());
+      childRect.x += (x - origX);
+      childRect.y += (y - origY);
+      child->SetXULBounds(aState, childRect);
+      child = nsBox::GetNextXULBox(child);
+    }
+  }
+
+  // Perform out-of-axis alignment for non-stretch alignments
+  if (!(frameState & NS_STATE_AUTO_STRETCH)) {
+    AlignChildren(aBox, aState);
+  }
+  
+  // That's it!  If you made it this far without having a nervous breakdown, 
+  // congratulations!  Go get yourself a beer.
+  return NS_OK;
+}
+
+void
+nsSprocketLayout::PopulateBoxSizes(nsIFrame* aBox, nsBoxLayoutState& aState, nsBoxSize*& aBoxSizes, nscoord& aMinSize, nscoord& aMaxSize, int32_t& aFlexes)
+{
+  // used for the equal size flag
+  nscoord biggestPrefWidth = 0;
+  nscoord biggestMinWidth = 0;
+  nscoord smallestMaxWidth = NS_INTRINSICSIZE;
+
+  nsFrameState frameState = nsFrameState(0);
+  GetFrameState(aBox, frameState);
+
+  //if (frameState & NS_STATE_CURRENTLY_IN_DEBUG)
+  //   printf("In debug\n");
+
+  aMinSize = 0;
+  aMaxSize = NS_INTRINSICSIZE;
+
+  bool isHorizontal;
+
+  if (IsXULHorizontal(aBox))
+     isHorizontal = true;
+  else
+     isHorizontal = false;
+
+  // this is a nice little optimization
+  // it turns out that if we only have 1 flexable child
+  // then it does not matter what its preferred size is
+  // there is nothing to flex it relative. This is great
+  // because we can avoid asking for a preferred size in this
+  // case. Why is this good? Well you might have html inside it
+  // and asking html for its preferred size is rather expensive.
+  // so we can just optimize it out this way.
+
+  // set flexes
+  nsIFrame* child = nsBox::GetChildXULBox(aBox);
+
+  aFlexes = 0;
+  nsBoxSize* currentBox = nullptr;
+
+#if 0
+  nsBoxSize* start = aBoxSizes;
+  
+  while(child)
+  {
+    // ok if we started with a list move down the list
+    // until we reach the end. Then start looking at childen.
+    // This feature is used extensively for Grid.
+    nscoord flex = 0;    
+
+    if (!start) {
+      if (!currentBox) {
+        aBoxSizes      = new (aState) nsBoxSize();
+        currentBox      = aBoxSizes;
+      } else {
+        currentBox->next      = new (aState) nsBoxSize();
+        currentBox      = currentBox->next;
+      }
+    
+
+      flex = child->GetXULFlex();
+
+      currentBox->flex = flex;
+      currentBox->collapsed = child->IsXULCollapsed();
+    } else {
+      flex = start->flex;
+      start = start->next;
+    }
+    
+    if (flex > 0) 
+       aFlexes++;
+   
+    child = GetNextXULBox(child);
+  }
+#endif
+
+  // get pref, min, max
+  child = nsBox::GetChildXULBox(aBox);
+  currentBox = aBoxSizes;
+  nsBoxSize* last = nullptr;
+
+  nscoord maxFlex = 0;
+  int32_t childCount = 0;
+
+  while(child)
+  {
+    while (currentBox && currentBox->bogus) {
+      last = currentBox;
+      currentBox = currentBox->next;
+    }
+    ++childCount;
+    nsSize pref(0,0);
+    nsSize minSize(0,0);
+    nsSize maxSize(NS_INTRINSICSIZE,NS_INTRINSICSIZE);
+    nscoord ascent = 0;
+    bool collapsed = child->IsXULCollapsed();
+
+    if (!collapsed) {
+    // only one flexible child? Cool we will just make its preferred size
+    // 0 then and not even have to ask for it.
+    //if (flexes != 1)  {
+
+      pref = child->GetXULPrefSize(aState);
+      minSize = child->GetXULMinSize(aState);
+      maxSize = nsBox::BoundsCheckMinMax(minSize, child->GetXULMaxSize(aState));
+      ascent = child->GetXULBoxAscent(aState);
+      nsMargin margin;
+      child->GetXULMargin(margin);
+      ascent += margin.top;
+    //}
+
+      pref = nsBox::BoundsCheck(minSize, pref, maxSize);
+
+      AddMargin(child, pref);
+      AddMargin(child, minSize);
+      AddMargin(child, maxSize);
+    }
+
+    if (!currentBox) {
+      // create one.
+      currentBox = new (aState) nsBoxSize();
+      if (!aBoxSizes) {
+        aBoxSizes = currentBox;
+        last = aBoxSizes;
+      } else {
+        last->next = currentBox;
+        last = currentBox;
+      }
+
+      nscoord minWidth;
+      nscoord maxWidth;
+      nscoord prefWidth;
+
+      // get sizes from child
+      if (isHorizontal) {
+          minWidth  = minSize.width;
+          maxWidth  = maxSize.width;
+          prefWidth = pref.width;
+      } else {
+          minWidth = minSize.height;
+          maxWidth = maxSize.height;
+          prefWidth = pref.height;
+      }
+
+      nscoord flex = child->GetXULFlex();
+
+      // set them if you collapsed you are not flexible.
+      if (collapsed) {
+        currentBox->flex = 0;
+      }
+      else {
+        if (flex > maxFlex) {
+          maxFlex = flex;
+        }
+        currentBox->flex = flex;
+      }
+
+      // we specified all our children are equal size;
+      if (frameState & NS_STATE_EQUAL_SIZE) {
+
+        if (prefWidth > biggestPrefWidth) 
+          biggestPrefWidth = prefWidth;
+
+        if (minWidth > biggestMinWidth) 
+          biggestMinWidth = minWidth;
+
+        if (maxWidth < smallestMaxWidth) 
+          smallestMaxWidth = maxWidth;
+      } else { // not we can set our children right now.
+        currentBox->pref    = prefWidth;
+        currentBox->min     = minWidth;
+        currentBox->max     = maxWidth;
+      }
+
+      NS_ASSERTION(minWidth <= prefWidth && prefWidth <= maxWidth,"Bad min, pref, max widths!");
+
+    }
+
+    if (!isHorizontal) {
+      if (minSize.width > aMinSize)
+        aMinSize = minSize.width;
+
+      if (maxSize.width < aMaxSize)
+        aMaxSize = maxSize.width;
+
+    } else {
+      if (minSize.height > aMinSize)
+        aMinSize = minSize.height;
+
+      if (maxSize.height < aMaxSize)
+        aMaxSize = maxSize.height;
+    }
+
+    currentBox->collapsed = collapsed;
+    aFlexes += currentBox->flex;
+
+    child = nsBox::GetNextXULBox(child);
+
+    last = currentBox;
+    currentBox = currentBox->next;
+
+  }
+
+  if (childCount > 0) {
+    nscoord maxAllowedFlex = nscoord_MAX / childCount;
+  
+    if (MOZ_UNLIKELY(maxFlex > maxAllowedFlex)) {
+      // clamp all the flexes
+      currentBox = aBoxSizes;
+      while (currentBox) {
+        currentBox->flex = std::min(currentBox->flex, maxAllowedFlex);
+        currentBox = currentBox->next;      
+      }
+    }
+  }
+#ifdef DEBUG
+  else {
+    NS_ASSERTION(maxFlex == 0, "How did that happen?");
+  }
+#endif
+
+  // we specified all our children are equal size;
+  if (frameState & NS_STATE_EQUAL_SIZE) {
+    smallestMaxWidth = std::max(smallestMaxWidth, biggestMinWidth);
+    biggestPrefWidth = nsBox::BoundsCheck(biggestMinWidth, biggestPrefWidth, smallestMaxWidth);
+
+    currentBox = aBoxSizes;
+
+    while(currentBox)
+    {
+      if (!currentBox->collapsed) {
+        currentBox->pref = biggestPrefWidth;
+        currentBox->min = biggestMinWidth;
+        currentBox->max = smallestMaxWidth;
+      } else {
+        currentBox->pref = 0;
+        currentBox->min = 0;
+        currentBox->max = 0;
+      }
+      currentBox = currentBox->next;
+    }
+  }
+
+}
+
+void
+nsSprocketLayout::ComputeChildsNextPosition(nsIFrame* aBox, 
+                                      const nscoord& aCurX, 
+                                      const nscoord& aCurY, 
+                                      nscoord& aNextX, 
+                                      nscoord& aNextY, 
+                                      const nsRect& aCurrentChildSize)
+{
+  // Get the position along the box axis for the child.
+  // The out-of-axis position is not set.
+  nsFrameState frameState = nsFrameState(0);
+  GetFrameState(aBox, frameState);
+
+  if (IsXULHorizontal(aBox)) {
+    // horizontal box's children.
+    if (frameState & NS_STATE_IS_DIRECTION_NORMAL)
+      aNextX = aCurX + aCurrentChildSize.width;
+    else
+      aNextX = aCurX - aCurrentChildSize.width;
+
+  } else {
+    // vertical box's children.
+    if (frameState & NS_STATE_IS_DIRECTION_NORMAL)
+      aNextY = aCurY + aCurrentChildSize.height;
+    else
+      aNextY = aCurY - aCurrentChildSize.height;
+  }
+}
+
+void
+nsSprocketLayout::AlignChildren(nsIFrame* aBox,
+                                nsBoxLayoutState& aState)
+{
+  nsFrameState frameState = nsFrameState(0);
+  GetFrameState(aBox, frameState);
+  bool isHorizontal = (frameState & NS_STATE_IS_HORIZONTAL) != 0;
+  nsRect clientRect;
+  aBox->GetXULClientRect(clientRect);
+
+  NS_PRECONDITION(!(frameState & NS_STATE_AUTO_STRETCH),
+                  "Only AlignChildren() with non-stretch alignment");
+
+  // These are only calculated if needed
+  nsIFrame::Halignment halign;
+  nsIFrame::Valignment valign;
+  nscoord maxAscent = 0;
+  bool isLTR;
+
+  if (isHorizontal) {
+    valign = aBox->GetXULVAlign();
+    if (valign == nsBoxFrame::vAlign_BaseLine) {
+      maxAscent = aBox->GetXULBoxAscent(aState);
+    }
+  } else {
+    isLTR = GetFrameDirection(aBox) == NS_STYLE_DIRECTION_LTR;
+    halign = aBox->GetXULHAlign();
+  }
+
+  nsIFrame* child = nsBox::GetChildXULBox(aBox);
+  while (child) {
+
+    nsMargin margin;
+    child->GetXULMargin(margin);
+    nsRect childRect = child->GetRect();
+
+    if (isHorizontal) {
+      const nscoord startAlign = clientRect.y + margin.top;
+      const nscoord endAlign =
+        clientRect.YMost() - margin.bottom - childRect.height;
+
+      nscoord y = 0;
+      switch (valign) {
+        case nsBoxFrame::vAlign_Top:
+          y = startAlign;
+          break;
+        case nsBoxFrame::vAlign_Middle:
+          // Should this center the border box?
+          // This centers the margin box, the historical behavior.
+          y = (startAlign + endAlign) / 2;
+          break;
+        case nsBoxFrame::vAlign_Bottom:
+          y = endAlign;
+          break;
+        case nsBoxFrame::vAlign_BaseLine:
+          // Alignments don't force the box to grow (only sizes do),
+          // so keep the children within the box.
+          y = maxAscent - child->GetXULBoxAscent(aState);
+          y = std::max(startAlign, y);
+          y = std::min(y, endAlign);
+          break;
+      }
+
+      childRect.y = y;
+
+    } else { // vertical box
+      const nscoord leftAlign = clientRect.x + margin.left;
+      const nscoord rightAlign =
+        clientRect.XMost() - margin.right - childRect.width;
+
+      nscoord x = 0;
+      switch (halign) {
+        case nsBoxFrame::hAlign_Left: // start
+          x = isLTR ? leftAlign : rightAlign;
+          break;
+        case nsBoxFrame::hAlign_Center:
+          x = (leftAlign + rightAlign) / 2;
+          break;
+        case nsBoxFrame::hAlign_Right: // end
+          x = isLTR ? rightAlign : leftAlign;
+          break;
+      }
+
+      childRect.x = x;
+    }
+
+    if (childRect.TopLeft() != child->GetPosition()) {
+      child->SetXULBounds(aState, childRect);
+    }
+
+    child = nsBox::GetNextXULBox(child);
+  }
+}
+
+void
+nsSprocketLayout::ChildResized(nsIFrame* aBox,
+                         nsBoxLayoutState& aState, 
+                         nsIFrame* aChild,
+                         nsBoxSize* aChildBoxSize,
+                         nsComputedBoxSize* aChildComputedSize,
+                         nsBoxSize* aBoxSizes, 
+                         nsComputedBoxSize* aComputedBoxSizes, 
+                         const nsRect& aChildLayoutRect, 
+                         nsRect& aChildActualRect, 
+                         nsRect& aContainingRect,
+                         int32_t aFlexes, 
+                         bool& aFinished)
+                         
+{
+      nsRect childCurrentRect(aChildLayoutRect);
+
+      bool isHorizontal = IsXULHorizontal(aBox);
+      nscoord childLayoutWidth  = GET_WIDTH(aChildLayoutRect,isHorizontal);
+      nscoord& childActualWidth  = GET_WIDTH(aChildActualRect,isHorizontal);
+      nscoord& containingWidth   = GET_WIDTH(aContainingRect,isHorizontal);   
+      
+      //nscoord childLayoutHeight = GET_HEIGHT(aChildLayoutRect,isHorizontal);
+      nscoord& childActualHeight = GET_HEIGHT(aChildActualRect,isHorizontal);
+      nscoord& containingHeight  = GET_HEIGHT(aContainingRect,isHorizontal);
+
+      bool recompute = false;
+
+      // if we are a horizontal box see if the child will fit inside us.
+      if ( childActualHeight > containingHeight) {
+            // if we are a horizontal box and the child is bigger than our height
+
+            // ok if the height changed then we need to reflow everyone but us at the new height
+            // so we will set the changed index to be us. And signal that we need a new pass.
+
+            nsSize min = aChild->GetXULMinSize(aState);            
+            nsSize max = nsBox::BoundsCheckMinMax(min, aChild->GetXULMaxSize(aState));
+            AddMargin(aChild, max);
+
+            if (isHorizontal)
+              childActualHeight = max.height < childActualHeight ? max.height : childActualHeight;
+            else
+              childActualHeight = max.width < childActualHeight ? max.width : childActualHeight;
+
+            // only set if it changes
+            if (childActualHeight > containingHeight) {
+                 containingHeight = childActualHeight;
+
+              // remember we do not need to clear the resized list because changing the height of a horizontal box
+              // will not affect the width of any of its children because block flow left to right, top to bottom. Just trust me
+              // on this one.
+              aFinished = false;
+
+              // only recompute if there are flexes.
+              if (aFlexes > 0) {
+                // relayout everything
+                recompute = true;
+                InvalidateComputedSizes(aComputedBoxSizes);
+                nsComputedBoxSize* node = aComputedBoxSizes;
+
+                while(node) {
+                  node->resized = false;
+                  node = node->next;
+                }
+
+              }              
+            }
+      } 
+      
+      if (childActualWidth > childLayoutWidth) {
+            nsSize min = aChild->GetXULMinSize(aState);
+            nsSize max = nsBox::BoundsCheckMinMax(min, aChild->GetXULMaxSize(aState));
+            
+            AddMargin(aChild, max);
+
+            // our width now becomes the new size
+
+            if (isHorizontal)
+              childActualWidth = max.width < childActualWidth ? max.width : childActualWidth;
+            else
+              childActualWidth = max.height < childActualWidth ? max.height : childActualWidth;
+
+            if (childActualWidth > childLayoutWidth) {
+               aChildComputedSize->size = childActualWidth;
+               aChildBoxSize->min = childActualWidth;
+               if (aChildBoxSize->pref < childActualWidth)
+                  aChildBoxSize->pref = childActualWidth;
+               if (aChildBoxSize->max < childActualWidth)
+                  aChildBoxSize->max = childActualWidth;
+
+              // if we have flexible elements with us then reflex things. Otherwise we can skip doing it.
+              if (aFlexes > 0) {
+                InvalidateComputedSizes(aComputedBoxSizes);
+
+                nsComputedBoxSize* node = aComputedBoxSizes;
+                aChildComputedSize->resized = true;
+
+                while(node) {
+                  if (node->resized)
+                      node->valid = true;
+                
+                  node = node->next;
+                }
+
+                recompute = true;
+                aFinished = false;
+              } else {
+                containingWidth += aChildComputedSize->size - childLayoutWidth;
+              }              
+            }
+      }
+
+      if (recompute)
+            ComputeChildSizes(aBox, aState, containingWidth, aBoxSizes, aComputedBoxSizes);
+
+      if (!childCurrentRect.IsEqualInterior(aChildActualRect)) {
+        // the childRect includes the margin
+        // make sure we remove it before setting 
+        // the bounds.
+        nsMargin margin(0,0,0,0);
+        aChild->GetXULMargin(margin);
+        nsRect rect(aChildActualRect);
+        if (rect.width >= margin.left + margin.right && rect.height >= margin.top + margin.bottom) 
+          rect.Deflate(margin);
+
+        aChild->SetXULBounds(aState, rect);
+        aChild->XULLayout(aState);
+      }
+
+}
+
+void
+nsSprocketLayout::InvalidateComputedSizes(nsComputedBoxSize* aComputedBoxSizes)
+{
+  while(aComputedBoxSizes) {
+      aComputedBoxSizes->valid = false;
+      aComputedBoxSizes = aComputedBoxSizes->next;
+  }
+}
+
+void
+nsSprocketLayout::ComputeChildSizes(nsIFrame* aBox,
+                           nsBoxLayoutState& aState, 
+                           nscoord& aGivenSize, 
+                           nsBoxSize* aBoxSizes, 
+                           nsComputedBoxSize*& aComputedBoxSizes)
+{  
+
+  //nscoord onePixel = aState.PresContext()->IntScaledPixelsToTwips(1);
+
+  int32_t sizeRemaining            = aGivenSize;
+  int32_t spacerConstantsRemaining = 0;
+
+   // ----- calculate the spacers constants and the size remaining -----
+
+  if (!aComputedBoxSizes)
+      aComputedBoxSizes = new (aState) nsComputedBoxSize();
+  
+  nsBoxSize*         boxSizes = aBoxSizes;
+  nsComputedBoxSize* computedBoxSizes = aComputedBoxSizes;
+  int32_t count = 0;
+  int32_t validCount = 0;
+
+  while (boxSizes) 
+  {
+
+    NS_ASSERTION((boxSizes->min <= boxSizes->pref && boxSizes->pref <= boxSizes->max),"bad pref, min, max size");
+
+    
+     // ignore collapsed children
+  //  if (boxSizes->collapsed) 
+  //  {
+    //  computedBoxSizes->valid = true;
+    //  computedBoxSizes->size = boxSizes->pref;
+     // validCount++;
+  //      boxSizes->flex = 0;
+   // }// else {
+    
+      if (computedBoxSizes->valid) { 
+        sizeRemaining -= computedBoxSizes->size;
+        validCount++;
+      } else {
+          if (boxSizes->flex == 0)
+          {
+            computedBoxSizes->valid = true;
+            computedBoxSizes->size = boxSizes->pref;
+            validCount++;
+          }
+
+          spacerConstantsRemaining += boxSizes->flex;
+          sizeRemaining -= boxSizes->pref;
+      }
+
+      sizeRemaining -= (boxSizes->left + boxSizes->right);
+
+    //} 
+
+    boxSizes = boxSizes->next;
+
+    if (boxSizes && !computedBoxSizes->next) 
+      computedBoxSizes->next = new (aState) nsComputedBoxSize();
+
+    computedBoxSizes = computedBoxSizes->next;
+    count++;
+  }
+
+  // everything accounted for?
+  if (validCount < count)
+  {
+    // ----- Ok we are give a size to fit into so stretch or squeeze to fit
+    // ----- Make sure we look at our min and max size
+    bool limit = true;
+    for (int pass=1; true == limit; pass++) 
+    {
+      limit = false;
+      boxSizes = aBoxSizes;
+      computedBoxSizes = aComputedBoxSizes;
+
+      while (boxSizes) { 
+
+        // ignore collapsed spacers
+
+   //    if (!boxSizes->collapsed) {
+      
+          nscoord pref = 0;
+          nscoord max  = NS_INTRINSICSIZE;
+          nscoord min  = 0;
+          nscoord flex = 0;
+
+          pref = boxSizes->pref;
+          min  = boxSizes->min;
+          max  = boxSizes->max;
+          flex = boxSizes->flex;
+
+          // ----- look at our min and max limits make sure we aren't too small or too big -----
+          if (!computedBoxSizes->valid) {
+            int32_t newSize = pref + int32_t(int64_t(sizeRemaining) * flex / spacerConstantsRemaining);
+
+            if (newSize<=min) {
+              computedBoxSizes->size = min;
+              computedBoxSizes->valid = true;
+              spacerConstantsRemaining -= flex;
+              sizeRemaining += pref;
+              sizeRemaining -= min;
+              limit = true;
+            } else if (newSize>=max) {
+              computedBoxSizes->size = max;
+              computedBoxSizes->valid = true;
+              spacerConstantsRemaining -= flex;
+              sizeRemaining += pref;
+              sizeRemaining -= max;
+              limit = true;
+            }
+          }
+       // }
+        boxSizes         = boxSizes->next;
+        computedBoxSizes = computedBoxSizes->next;
+      }
+    }
+  }          
+
+  // ---- once we have removed and min and max issues just stretch us out in the remaining space
+  // ---- or shrink us. Depends on the size remaining and the spacer constants
+  aGivenSize = 0;
+  boxSizes = aBoxSizes;
+  computedBoxSizes = aComputedBoxSizes;
+
+  while (boxSizes) { 
+
+    // ignore collapsed spacers
+  //  if (!(boxSizes && boxSizes->collapsed)) {
+    
+      nscoord pref = 0;
+      nscoord flex = 0;
+      pref = boxSizes->pref;
+      flex = boxSizes->flex;
+
+      if (!computedBoxSizes->valid) {
+        computedBoxSizes->size = pref + int32_t(int64_t(sizeRemaining) * flex / spacerConstantsRemaining);
+        computedBoxSizes->valid = true;
+      }
+
+      aGivenSize += (boxSizes->left + boxSizes->right);
+      aGivenSize += computedBoxSizes->size;
+
+   // }
+
+    boxSizes         = boxSizes->next;
+    computedBoxSizes = computedBoxSizes->next;
+  }
+}
+
+
+nsSize
+nsSprocketLayout::GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+   nsSize vpref (0, 0); 
+   bool isHorizontal = IsXULHorizontal(aBox);
+
+   nscoord biggestPref = 0;
+
+   // run through all the children and get their min, max, and preferred sizes
+   // return us the size of the box
+
+   nsIFrame* child = nsBox::GetChildXULBox(aBox);
+   nsFrameState frameState = nsFrameState(0);
+   GetFrameState(aBox, frameState);
+   bool isEqual = !!(frameState & NS_STATE_EQUAL_SIZE);
+   int32_t count = 0;
+   
+   while (child) 
+   {  
+      // ignore collapsed children
+      if (!child->IsXULCollapsed())
+      {
+        nsSize pref = child->GetXULPrefSize(aState);
+        AddMargin(child, pref);
+
+        if (isEqual) {
+          if (isHorizontal)
+          {
+            if (pref.width > biggestPref)
+              biggestPref = pref.width;
+          } else {
+            if (pref.height > biggestPref)
+              biggestPref = pref.height;
+          }
+        }
+
+        AddLargestSize(vpref, pref, isHorizontal);
+        count++;
+      }
+
+      child = nsBox::GetNextXULBox(child);
+   }
+
+   if (isEqual) {
+      if (isHorizontal)
+         vpref.width = biggestPref*count;
+      else
+         vpref.height = biggestPref*count;
+   }
+    
+   // now add our border and padding
+   AddBorderAndPadding(aBox, vpref);
+
+  return vpref;
+}
+
+nsSize
+nsSprocketLayout::GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+   nsSize minSize (0, 0);
+   bool isHorizontal = IsXULHorizontal(aBox);
+
+   nscoord biggestMin = 0;
+
+
+   // run through all the children and get their min, max, and preferred sizes
+   // return us the size of the box
+
+   nsIFrame* child = nsBox::GetChildXULBox(aBox);
+   nsFrameState frameState = nsFrameState(0);
+   GetFrameState(aBox, frameState);
+   bool isEqual = !!(frameState & NS_STATE_EQUAL_SIZE);
+   int32_t count = 0;
+
+   while (child) 
+   {  
+       // ignore collapsed children
+      if (!child->IsXULCollapsed())
+      {
+        nsSize min = child->GetXULMinSize(aState);
+        nsSize pref(0,0);
+        
+        // if the child is not flexible then
+        // its min size is its pref size.
+        if (child->GetXULFlex() == 0) {
+            pref = child->GetXULPrefSize(aState);
+            if (isHorizontal)
+               min.width = pref.width;
+            else
+               min.height = pref.height;
+        }
+
+        if (isEqual) {
+          if (isHorizontal)
+          {
+            if (min.width > biggestMin)
+              biggestMin = min.width;
+          } else {
+            if (min.height > biggestMin)
+              biggestMin = min.height;
+          }
+        }
+
+        AddMargin(child, min);
+        AddLargestSize(minSize, min, isHorizontal);
+        count++;
+      }
+
+      child = nsBox::GetNextXULBox(child);
+   }
+
+   
+   if (isEqual) {
+      if (isHorizontal)
+         minSize.width = biggestMin*count;
+      else
+         minSize.height = biggestMin*count;
+   }
+
+  // now add our border and padding
+  AddBorderAndPadding(aBox, minSize);
+
+  return minSize;
+}
+
+nsSize
+nsSprocketLayout::GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+
+  bool isHorizontal = IsXULHorizontal(aBox);
+
+   nscoord smallestMax = NS_INTRINSICSIZE;
+   nsSize maxSize (NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+
+   // run through all the children and get their min, max, and preferred sizes
+   // return us the size of the box
+
+   nsIFrame* child = nsBox::GetChildXULBox(aBox);
+   nsFrameState frameState = nsFrameState(0);
+   GetFrameState(aBox, frameState);
+   bool isEqual = !!(frameState & NS_STATE_EQUAL_SIZE);
+   int32_t count = 0;
+
+   while (child) 
+   {  
+      // ignore collapsed children
+      if (!child->IsXULCollapsed())
+      {
+        // if completely redefined don't even ask our child for its size.
+        nsSize min = child->GetXULMinSize(aState);
+        nsSize max = nsBox::BoundsCheckMinMax(min, child->GetXULMaxSize(aState));
+
+        AddMargin(child, max);
+        AddSmallestSize(maxSize, max, isHorizontal);
+
+        if (isEqual) {
+          if (isHorizontal)
+          {
+            if (max.width < smallestMax)
+              smallestMax = max.width;
+          } else {
+            if (max.height < smallestMax)
+              smallestMax = max.height;
+          }
+        }
+        count++;
+      }
+
+      child = nsBox::GetNextXULBox(child);
+   }
+
+   if (isEqual) {
+     if (isHorizontal) {
+         if (smallestMax != NS_INTRINSICSIZE)
+            maxSize.width = smallestMax*count;
+         else
+            maxSize.width = NS_INTRINSICSIZE;
+     } else {
+         if (smallestMax != NS_INTRINSICSIZE)
+            maxSize.height = smallestMax*count;
+         else
+            maxSize.height = NS_INTRINSICSIZE;
+     }
+   }
+
+  // now add our border and padding
+  AddBorderAndPadding(aBox, maxSize);
+
+  return maxSize;
+}
+
+
+nscoord
+nsSprocketLayout::GetAscent(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+   nscoord vAscent = 0;
+
+   bool isHorizontal = IsXULHorizontal(aBox);
+
+   // run through all the children and get their min, max, and preferred sizes
+   // return us the size of the box
+   
+   nsIFrame* child = nsBox::GetChildXULBox(aBox);
+   
+   while (child) 
+   {  
+      // ignore collapsed children
+      //if (!child->IsXULCollapsed())
+      //{
+        // if completely redefined don't even ask our child for its size.
+        nscoord ascent = child->GetXULBoxAscent(aState);
+
+        nsMargin margin;
+        child->GetXULMargin(margin);
+        ascent += margin.top;
+
+        if (isHorizontal)
+        {
+          if (ascent > vAscent)
+            vAscent = ascent;
+        } else {
+          if (vAscent == 0)
+            vAscent = ascent;
+        }
+      //}
+
+      child = nsBox::GetNextXULBox(child);      
+   }
+
+   nsMargin borderPadding;
+   aBox->GetXULBorderAndPadding(borderPadding);
+
+   return vAscent + borderPadding.top;
+}
+
+void
+nsSprocketLayout::SetLargestSize(nsSize& aSize1, const nsSize& aSize2, bool aIsHorizontal)
+{
+  if (aIsHorizontal)
+  {
+    if (aSize1.height < aSize2.height)
+       aSize1.height = aSize2.height;
+  } else {
+    if (aSize1.width < aSize2.width)
+       aSize1.width = aSize2.width;
+  }
+}
+
+void
+nsSprocketLayout::SetSmallestSize(nsSize& aSize1, const nsSize& aSize2, bool aIsHorizontal)
+{
+  if (aIsHorizontal)
+  {
+    if (aSize1.height > aSize2.height)
+       aSize1.height = aSize2.height;
+  } else {
+    if (aSize1.width > aSize2.width)
+       aSize1.width = aSize2.width;
+
+  }
+}
+
+void
+nsSprocketLayout::AddLargestSize(nsSize& aSize, const nsSize& aSizeToAdd, bool aIsHorizontal)
+{
+  if (aIsHorizontal)
+    AddCoord(aSize.width, aSizeToAdd.width);
+  else
+    AddCoord(aSize.height, aSizeToAdd.height);
+
+  SetLargestSize(aSize, aSizeToAdd, aIsHorizontal);
+}
+
+void
+nsSprocketLayout::AddCoord(nscoord& aCoord, nscoord aCoordToAdd)
+{
+  if (aCoord != NS_INTRINSICSIZE) 
+  {
+    if (aCoordToAdd == NS_INTRINSICSIZE)
+      aCoord = aCoordToAdd;
+    else
+      aCoord += aCoordToAdd;
+  }
+}
+void
+nsSprocketLayout::AddSmallestSize(nsSize& aSize, const nsSize& aSizeToAdd, bool aIsHorizontal)
+{
+  if (aIsHorizontal)
+    AddCoord(aSize.width, aSizeToAdd.width);
+  else
+    AddCoord(aSize.height, aSizeToAdd.height);
+    
+  SetSmallestSize(aSize, aSizeToAdd, aIsHorizontal);
+}
+
+bool
+nsSprocketLayout::GetDefaultFlex(int32_t& aFlex)
+{
+    aFlex = 0;
+    return true;
+}
+
+nsComputedBoxSize::nsComputedBoxSize()
+{
+  resized = false;
+  valid = false;
+  size = 0;
+  next = nullptr;
+}
+
+nsBoxSize::nsBoxSize()
+{
+  pref = 0;
+  min = 0;
+  max = NS_INTRINSICSIZE;
+  collapsed = false;
+  left = 0;
+  right = 0;
+  flex = 0;
+  next = nullptr;
+  bogus = false;
+}
+
+
+void* 
+nsBoxSize::operator new(size_t sz, nsBoxLayoutState& aState) CPP_THROW_NEW
+{
+  return mozilla::AutoStackArena::Allocate(sz);
+}
+
+
+void 
+nsBoxSize::operator delete(void* aPtr, size_t sz)
+{
+}
+
+
+void* 
+nsComputedBoxSize::operator new(size_t sz, nsBoxLayoutState& aState) CPP_THROW_NEW
+{
+   return mozilla::AutoStackArena::Allocate(sz);
+}
+
+void 
+nsComputedBoxSize::operator delete(void* aPtr, size_t sz)
+{
+}
diff --git a/layout/xul/nsSprocketLayout.h b/layout/xul/nsSprocketLayout.h
new file mode 100644
index 0000000000..0f15dce442
--- /dev/null
+++ b/layout/xul/nsSprocketLayout.h
@@ -0,0 +1,142 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsSprocketLayout_h___
+#define nsSprocketLayout_h___
+
+#include "mozilla/Attributes.h"
+#include "nsBoxLayout.h"
+#include "nsCOMPtr.h"
+#include "nsIFrame.h"
+
+class nsBoxSize
+{
+public:
+
+  nsBoxSize();
+
+  nscoord pref;
+  nscoord min;
+  nscoord max;
+  nscoord flex;
+  nscoord left;
+  nscoord right;
+  bool    collapsed;
+  bool    bogus;
+
+  nsBoxSize* next;
+
+  void* operator new(size_t sz, nsBoxLayoutState& aState) CPP_THROW_NEW;
+  void operator delete(void* aPtr, size_t sz);
+};
+
+class nsComputedBoxSize
+{
+public:
+  nsComputedBoxSize();
+
+  nscoord size;
+  bool    valid;
+  bool    resized;
+  nsComputedBoxSize* next;
+
+  void* operator new(size_t sz, nsBoxLayoutState& aState) CPP_THROW_NEW;
+  void operator delete(void* aPtr, size_t sz);
+};
+
+#define GET_WIDTH(size, isHorizontal) (isHorizontal ? size.width : size.height)
+#define GET_HEIGHT(size, isHorizontal) (isHorizontal ? size.height : size.width)
+#define GET_X(size, isHorizontal) (isHorizontal ? size.x : size.y)
+#define GET_Y(size, isHorizontal) (isHorizontal ? size.y : size.x)
+#define GET_COORD(aX, aY, isHorizontal) (isHorizontal ? aX : aY)
+
+#define SET_WIDTH(size, coord, isHorizontal)  if (isHorizontal) { (size).width  = (coord); } else { (size).height = (coord); }
+#define SET_HEIGHT(size, coord, isHorizontal) if (isHorizontal) { (size).height = (coord); } else { (size).width  = (coord); }
+#define SET_X(size, coord, isHorizontal) if (isHorizontal) { (size).x = (coord); } else { (size).y  = (coord); }
+#define SET_Y(size, coord, isHorizontal) if (isHorizontal) { (size).y = (coord); } else { (size).x  = (coord); }
+
+#define SET_COORD(aX, aY, coord, isHorizontal) if (isHorizontal) { aX = (coord); } else { aY  = (coord); }
+
+nsresult NS_NewSprocketLayout(nsCOMPtr<nsBoxLayout>& aNewLayout);
+
+class nsSprocketLayout : public nsBoxLayout {
+
+public:
+
+  friend nsresult NS_NewSprocketLayout(nsCOMPtr<nsBoxLayout>& aNewLayout);
+  static void Shutdown();
+
+  NS_IMETHOD XULLayout(nsIFrame* aBox, nsBoxLayoutState& aState) override;
+
+  virtual nsSize GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nscoord GetAscent(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+
+  nsSprocketLayout();
+
+  static bool IsXULHorizontal(nsIFrame* aBox);
+
+  static void SetLargestSize(nsSize& aSize1, const nsSize& aSize2, bool aIsHorizontal);
+  static void SetSmallestSize(nsSize& aSize1, const nsSize& aSize2, bool aIsHorizontal);
+
+  static void AddLargestSize(nsSize& aSize, const nsSize& aSizeToAdd, bool aIsHorizontal);
+  static void AddSmallestSize(nsSize& aSize, const nsSize& aSizeToAdd, bool aIsHorizontal);
+  static void AddCoord(nscoord& aCoord, nscoord aCoordToAdd);
+
+protected:
+
+
+  void ComputeChildsNextPosition(nsIFrame* aBox,
+                                 const nscoord& aCurX, 
+                                 const nscoord& aCurY, 
+                                 nscoord& aNextX, 
+                                 nscoord& aNextY, 
+                                 const nsRect& aChildSize);
+
+  void ChildResized(nsIFrame* aBox,
+                    nsBoxLayoutState& aState, 
+                    nsIFrame* aChild,
+                    nsBoxSize* aChildBoxSize, 
+                    nsComputedBoxSize* aChildComputedBoxSize, 
+                    nsBoxSize* aBoxSizes, 
+                    nsComputedBoxSize* aComputedBoxSizes, 
+                    const nsRect& aChildLayoutRect, 
+                    nsRect& aChildActualRect, 
+                    nsRect& aContainingRect, 
+                    int32_t aFlexes, 
+                    bool& aFinished);
+
+  void AlignChildren(nsIFrame* aBox,
+                     nsBoxLayoutState& aState);
+
+  virtual void ComputeChildSizes(nsIFrame* aBox, 
+                         nsBoxLayoutState& aState, 
+                         nscoord& aGivenSize, 
+                         nsBoxSize* aBoxSizes, 
+                         nsComputedBoxSize*& aComputedBoxSizes);
+
+
+  virtual void PopulateBoxSizes(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState,
+                                nsBoxSize*& aBoxSizes, nscoord& aMinSize,
+                                nscoord& aMaxSize, int32_t& aFlexes);
+
+  virtual void InvalidateComputedSizes(nsComputedBoxSize* aComputedBoxSizes);
+
+  virtual bool GetDefaultFlex(int32_t& aFlex);
+
+  virtual void GetFrameState(nsIFrame* aBox, nsFrameState& aState);
+
+private:
+
+
+  // because the sprocket layout manager has no instance variables. We 
+  // can make a static one and reuse it everywhere.
+  static nsBoxLayout* gInstance;
+
+};
+
+#endif
+
diff --git a/layout/xul/nsStackFrame.cpp b/layout/xul/nsStackFrame.cpp
new file mode 100644
index 0000000000..437d558f91
--- /dev/null
+++ b/layout/xul/nsStackFrame.cpp
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsStackFrame.h"
+#include "nsStyleContext.h"
+#include "nsIContent.h"
+#include "nsCOMPtr.h"
+#include "nsHTMLParts.h"
+#include "nsIPresShell.h"
+#include "nsCSSRendering.h"
+#include "nsBoxLayoutState.h"
+#include "nsStackLayout.h"
+#include "nsDisplayList.h"
+
+nsIFrame*
+NS_NewStackFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsStackFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsStackFrame)
+
+nsStackFrame::nsStackFrame(nsStyleContext* aContext):
+  nsBoxFrame(aContext)
+{
+  nsCOMPtr<nsBoxLayout> layout;
+  NS_NewStackLayout(layout);
+  SetXULLayoutManager(layout);
+}
+
+// REVIEW: The old code put everything in the background layer. To be more
+// consistent with the way other frames work, I'm putting everything in the
+// Content() (i.e., foreground) layer (see nsFrame::BuildDisplayListForChild,
+// the case for stacking context but non-positioned, non-floating frames).
+// This could easily be changed back by hacking nsBoxFrame::BuildDisplayListInternal
+// a bit more.
+void
+nsStackFrame::BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                          const nsRect&           aDirtyRect,
+                                          const nsDisplayListSet& aLists)
+{
+  // BuildDisplayListForChild puts stacking contexts into the PositionedDescendants
+  // list. So we need to map that list to aLists.Content(). This is an easy way to
+  // do that.
+  nsDisplayList* content = aLists.Content();
+  nsDisplayListSet kidLists(content, content, content, content, content, content);
+  nsIFrame* kid = mFrames.FirstChild();
+  while (kid) {
+    // Force each child into its own true stacking context.
+    BuildDisplayListForChild(aBuilder, kid, aDirtyRect, kidLists,
+                             DISPLAY_CHILD_FORCE_STACKING_CONTEXT);
+    kid = kid->GetNextSibling();
+  }
+}
diff --git a/layout/xul/nsStackFrame.h b/layout/xul/nsStackFrame.h
new file mode 100644
index 0000000000..b90a16b213
--- /dev/null
+++ b/layout/xul/nsStackFrame.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+
+  Eric D Vaughan
+  A frame that can have multiple children. Only one child may be displayed at one time. So the
+  can be flipped though like a Stack of cards.
+ 
+**/
+
+#ifndef nsStackFrame_h___
+#define nsStackFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+class nsStackFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewStackFrame(nsIPresShell* aPresShell,
+                                    nsStyleContext* aContext);
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override
+  {
+    return MakeFrameName(NS_LITERAL_STRING("Stack"), aResult);
+  }
+#endif
+
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) override;
+
+protected:
+  explicit nsStackFrame(nsStyleContext* aContext);
+}; // class nsStackFrame
+
+
+
+#endif
+
diff --git a/layout/xul/nsStackLayout.cpp b/layout/xul/nsStackLayout.cpp
new file mode 100644
index 0000000000..6072e0612b
--- /dev/null
+++ b/layout/xul/nsStackLayout.cpp
@@ -0,0 +1,385 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsStackLayout.h"
+#include "nsCOMPtr.h"
+#include "nsBoxLayoutState.h"
+#include "nsBox.h"
+#include "nsBoxFrame.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+#include "nsNameSpaceManager.h"
+
+using namespace mozilla;
+
+nsBoxLayout* nsStackLayout::gInstance = nullptr;
+
+#define SPECIFIED_LEFT (1 << NS_SIDE_LEFT)
+#define SPECIFIED_RIGHT (1 << NS_SIDE_RIGHT)
+#define SPECIFIED_TOP (1 << NS_SIDE_TOP)
+#define SPECIFIED_BOTTOM (1 << NS_SIDE_BOTTOM)
+
+nsresult
+NS_NewStackLayout(nsCOMPtr<nsBoxLayout>& aNewLayout)
+{
+  if (!nsStackLayout::gInstance) {
+    nsStackLayout::gInstance = new nsStackLayout();
+    NS_IF_ADDREF(nsStackLayout::gInstance);
+  }
+  // we have not instance variables so just return our static one.
+  aNewLayout = nsStackLayout::gInstance;
+  return NS_OK;
+} 
+
+/*static*/ void
+nsStackLayout::Shutdown()
+{
+  NS_IF_RELEASE(gInstance);
+}
+
+nsStackLayout::nsStackLayout()
+{
+}
+
+/*
+ * Sizing: we are as wide as the widest child plus its left offset
+ * we are tall as the tallest child plus its top offset.
+ *
+ * Only children which have -moz-stack-sizing set to stretch-to-fit
+ * (the default) will be included in the size computations.
+ */
+
+nsSize
+nsStackLayout::GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  nsSize prefSize (0, 0);
+
+  nsIFrame* child = nsBox::GetChildXULBox(aBox);
+  while (child) {
+    if (child->StyleXUL()->mStretchStack) {
+      nsSize pref = child->GetXULPrefSize(aState);
+
+      AddMargin(child, pref);
+      nsMargin offset;
+      GetOffset(child, offset);
+      pref.width += offset.LeftRight();
+      pref.height += offset.TopBottom();
+      AddLargestSize(prefSize, pref);
+    }
+
+    child = nsBox::GetNextXULBox(child);
+  }
+
+  AddBorderAndPadding(aBox, prefSize);
+
+  return prefSize;
+}
+
+nsSize
+nsStackLayout::GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  nsSize minSize (0, 0);
+
+  nsIFrame* child = nsBox::GetChildXULBox(aBox);
+  while (child) {
+    if (child->StyleXUL()->mStretchStack) {
+      nsSize min = child->GetXULMinSize(aState);
+
+      AddMargin(child, min);
+      nsMargin offset;
+      GetOffset(child, offset);
+      min.width += offset.LeftRight();
+      min.height += offset.TopBottom();
+      AddLargestSize(minSize, min);
+    }
+
+    child = nsBox::GetNextXULBox(child);
+  }
+
+  AddBorderAndPadding(aBox, minSize);
+
+  return minSize;
+}
+
+nsSize
+nsStackLayout::GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  nsSize maxSize (NS_INTRINSICSIZE, NS_INTRINSICSIZE);
+
+  nsIFrame* child = nsBox::GetChildXULBox(aBox);
+  while (child) {
+    if (child->StyleXUL()->mStretchStack) {
+      nsSize min = child->GetXULMinSize(aState);
+      nsSize max = child->GetXULMaxSize(aState);
+
+      max = nsBox::BoundsCheckMinMax(min, max);
+
+      AddMargin(child, max);
+      nsMargin offset;
+      GetOffset(child, offset);
+      max.width += offset.LeftRight();
+      max.height += offset.TopBottom();
+      AddSmallestSize(maxSize, max);
+    }
+
+    child = nsBox::GetNextXULBox(child);
+  }
+
+  AddBorderAndPadding(aBox, maxSize);
+
+  return maxSize;
+}
+
+
+nscoord
+nsStackLayout::GetAscent(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  nscoord vAscent = 0;
+
+  nsIFrame* child = nsBox::GetChildXULBox(aBox);
+  while (child) {  
+    nscoord ascent = child->GetXULBoxAscent(aState);
+    nsMargin margin;
+    child->GetXULMargin(margin);
+    ascent += margin.top;
+    if (ascent > vAscent)
+      vAscent = ascent;
+
+    child = nsBox::GetNextXULBox(child);
+  }
+
+  return vAscent;
+}
+
+uint8_t
+nsStackLayout::GetOffset(nsIFrame* aChild, nsMargin& aOffset)
+{
+  aOffset = nsMargin(0, 0, 0, 0);
+
+  // get the left, right, top and bottom offsets
+
+  // As an optimization, we cache the fact that we are not positioned to avoid
+  // wasting time fetching attributes.
+  if (aChild->IsXULBoxFrame() &&
+      (aChild->GetStateBits() & NS_STATE_STACK_NOT_POSITIONED))
+    return 0;
+
+  uint8_t offsetSpecified = 0;
+  nsIContent* content = aChild->GetContent();
+  if (content) {
+    bool ltr = aChild->StyleVisibility()->mDirection == NS_STYLE_DIRECTION_LTR;
+    nsAutoString value;
+    nsresult error;
+
+    content->GetAttr(kNameSpaceID_None, nsGkAtoms::start, value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+      if (ltr) {
+        aOffset.left =
+          nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+        offsetSpecified |= SPECIFIED_LEFT;
+      } else {
+        aOffset.right =
+          nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+        offsetSpecified |= SPECIFIED_RIGHT;
+      }
+    }
+
+    content->GetAttr(kNameSpaceID_None, nsGkAtoms::end, value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+      if (ltr) {
+        aOffset.right =
+          nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+        offsetSpecified |= SPECIFIED_RIGHT;
+      } else {
+        aOffset.left =
+          nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+        offsetSpecified |= SPECIFIED_LEFT;
+      }
+    }
+
+    content->GetAttr(kNameSpaceID_None, nsGkAtoms::left, value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+      aOffset.left =
+        nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      offsetSpecified |= SPECIFIED_LEFT;
+    }
+
+    content->GetAttr(kNameSpaceID_None, nsGkAtoms::right, value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+      aOffset.right =
+        nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      offsetSpecified |= SPECIFIED_RIGHT;
+    }
+
+    content->GetAttr(kNameSpaceID_None, nsGkAtoms::top, value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+      aOffset.top =
+        nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      offsetSpecified |= SPECIFIED_TOP;
+    }
+
+    content->GetAttr(kNameSpaceID_None, nsGkAtoms::bottom, value);
+    if (!value.IsEmpty()) {
+      value.Trim("%");
+      aOffset.bottom =
+        nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
+      offsetSpecified |= SPECIFIED_BOTTOM;
+    }
+  }
+
+  if (!offsetSpecified && aChild->IsXULBoxFrame()) {
+    // If no offset was specified at all, then we cache this fact to avoid requerying
+    // CSS or the content model.
+    aChild->AddStateBits(NS_STATE_STACK_NOT_POSITIONED);
+  }
+
+  return offsetSpecified;
+}
+
+
+NS_IMETHODIMP
+nsStackLayout::XULLayout(nsIFrame* aBox, nsBoxLayoutState& aState)
+{
+  nsRect clientRect;
+  aBox->GetXULClientRect(clientRect);
+
+  bool grow;
+
+  do {
+    nsIFrame* child = nsBox::GetChildXULBox(aBox);
+    grow = false;
+
+    while (child) 
+    {  
+      nsMargin margin;
+      child->GetXULMargin(margin);
+      nsRect childRect(clientRect);
+      childRect.Deflate(margin);
+
+      if (childRect.width < 0)
+        childRect.width = 0;
+
+      if (childRect.height < 0)
+        childRect.height = 0;
+
+      nsRect oldRect(child->GetRect());
+      bool sizeChanged = !oldRect.IsEqualEdges(childRect);
+
+      // only lay out dirty children or children whose sizes have changed
+      if (sizeChanged || NS_SUBTREE_DIRTY(child)) {
+          // add in the child's margin
+          nsMargin margin;
+          child->GetXULMargin(margin);
+
+          // obtain our offset from the top left border of the stack's content box.
+          nsMargin offset;
+          uint8_t offsetSpecified = GetOffset(child, offset);
+
+          // Set the position and size based on which offsets have been specified:
+          //   left only - offset from left edge, preferred width
+          //   right only - offset from right edge, preferred width
+          //   left and right - offset from left and right edges, width in between this
+          //   neither - no offset, full width of stack
+          // Vertical direction is similar.
+          //
+          // Margins on the child are also included in the edge offsets
+          if (offsetSpecified) {
+            nsSize min = child->GetXULMinSize(aState);
+            nsSize max = child->GetXULMaxSize(aState);
+            if (offsetSpecified & SPECIFIED_LEFT) {
+              childRect.x = clientRect.x + offset.left + margin.left;
+              if (offsetSpecified & SPECIFIED_RIGHT) {
+                nscoord width = clientRect.width - offset.LeftRight() - margin.LeftRight();
+                childRect.width = clamped(width, min.width, max.width);
+              }
+              else {
+                nscoord width = child->GetXULPrefSize(aState).width;
+                childRect.width = clamped(width, min.width, max.width);
+              }
+            }
+            else if (offsetSpecified & SPECIFIED_RIGHT) {
+              nscoord width = child->GetXULPrefSize(aState).width;
+              childRect.width = clamped(width, min.width, max.width);
+              childRect.x = clientRect.XMost() - offset.right - margin.right - childRect.width;
+            }
+
+            if (offsetSpecified & SPECIFIED_TOP) {
+              childRect.y = clientRect.y + offset.top + margin.top;
+              if (offsetSpecified & SPECIFIED_BOTTOM) {
+                nscoord height = clientRect.height - offset.TopBottom() - margin.TopBottom();
+                childRect.height = clamped(height, min.height, max.height);
+              }
+              else {
+                nscoord height = child->GetXULPrefSize(aState).height;
+                childRect.height = clamped(height, min.height, max.height);
+              }
+            }
+            else if (offsetSpecified & SPECIFIED_BOTTOM) {
+              nscoord height = child->GetXULPrefSize(aState).height;
+              childRect.height = clamped(height, min.height, max.height);
+              childRect.y = clientRect.YMost() - offset.bottom - margin.bottom - childRect.height;
+            }
+          }
+
+          // Now place the child.
+          child->SetXULBounds(aState, childRect);
+
+          // Flow the child.
+          child->XULLayout(aState);
+
+          // Get the child's new rect.
+          childRect = child->GetRect();
+          childRect.Inflate(margin);
+
+          if (child->StyleXUL()->mStretchStack) {
+            // Did the child push back on us and get bigger?
+            if (offset.LeftRight() + childRect.width > clientRect.width) {
+              clientRect.width = childRect.width + offset.LeftRight();
+              grow = true;
+            }
+
+            if (offset.TopBottom() + childRect.height > clientRect.height) {
+              clientRect.height = childRect.height + offset.TopBottom();
+              grow = true;
+            }
+          }
+       }
+
+       child = nsBox::GetNextXULBox(child);
+     }
+   } while (grow);
+   
+   // if some HTML inside us got bigger we need to force ourselves to
+   // get bigger
+   nsRect bounds(aBox->GetRect());
+   nsMargin bp;
+   aBox->GetXULBorderAndPadding(bp);
+   clientRect.Inflate(bp);
+
+   if (clientRect.width > bounds.width || clientRect.height > bounds.height)
+   {
+     if (clientRect.width > bounds.width)
+       bounds.width = clientRect.width;
+     if (clientRect.height > bounds.height)
+       bounds.height = clientRect.height;
+
+     aBox->SetXULBounds(aState, bounds);
+   }
+
+   return NS_OK;
+}
+
diff --git a/layout/xul/nsStackLayout.h b/layout/xul/nsStackLayout.h
new file mode 100644
index 0000000000..1eb1a6318d
--- /dev/null
+++ b/layout/xul/nsStackLayout.h
@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+
+  Eric D Vaughan
+  A frame that can have multiple children. Only one child may be displayed at one time. So the
+  can be flipped though like a deck of cards.
+ 
+**/
+
+#ifndef nsStackLayout_h___
+#define nsStackLayout_h___
+
+#include "mozilla/Attributes.h"
+#include "nsBoxLayout.h"
+#include "nsCOMPtr.h"
+#include "nsCoord.h"
+
+class nsIPresShell;
+
+nsresult NS_NewStackLayout(nsCOMPtr<nsBoxLayout>& aNewLayout);
+
+class nsStackLayout : public nsBoxLayout
+{
+public:
+
+  friend nsresult NS_NewStackLayout(nsCOMPtr<nsBoxLayout>& aNewLayout);
+  static void Shutdown();
+
+  nsStackLayout();
+
+  NS_IMETHOD XULLayout(nsIFrame* aBox, nsBoxLayoutState& aState) override;
+
+  virtual nsSize GetXULPrefSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMaxSize(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nscoord GetAscent(nsIFrame* aBox, nsBoxLayoutState& aBoxLayoutState) override;
+
+  // get the child offsets for aChild and set them in aMargin. Returns a
+  // bitfield mask of the SPECIFIED_LEFT, SPECIFIED_RIGHT, SPECIFIED_TOP and
+  // SPECIFIED_BOTTOM offsets indicating which sides have been specified by
+  // attributes.
+  static uint8_t GetOffset(nsIFrame* aChild, nsMargin& aMargin);
+
+private:
+  static nsBoxLayout* gInstance;
+
+}; // class nsStackLayout
+
+
+
+#endif
+
diff --git a/layout/xul/nsTextBoxFrame.cpp b/layout/xul/nsTextBoxFrame.cpp
new file mode 100644
index 0000000000..c82d3d6b9b
--- /dev/null
+++ b/layout/xul/nsTextBoxFrame.cpp
@@ -0,0 +1,1241 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=4 sw=4 sts=4 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTextBoxFrame.h"
+
+#include "gfx2DGlue.h"
+#include "gfxUtils.h"
+#include "mozilla/gfx/2D.h"
+#include "nsFontMetrics.h"
+#include "nsReadableUtils.h"
+#include "nsCOMPtr.h"
+#include "nsGkAtoms.h"
+#include "nsPresContext.h"
+#include "nsRenderingContext.h"
+#include "nsStyleContext.h"
+#include "nsIContent.h"
+#include "nsNameSpaceManager.h"
+#include "nsBoxLayoutState.h"
+#include "nsMenuBarListener.h"
+#include "nsXPIDLString.h"
+#include "nsIServiceManager.h"
+#include "nsIDOMElement.h"
+#include "nsIDOMXULLabelElement.h"
+#include "mozilla/EventStateManager.h"
+#include "nsITheme.h"
+#include "nsUnicharUtils.h"
+#include "nsContentUtils.h"
+#include "nsDisplayList.h"
+#include "nsCSSRendering.h"
+#include "nsIReflowCallback.h"
+#include "nsBoxFrame.h"
+#include "mozilla/Preferences.h"
+#include "nsLayoutUtils.h"
+#include "mozilla/Attributes.h"
+#include "nsUnicodeProperties.h"
+
+#ifdef ACCESSIBILITY
+#include "nsAccessibilityService.h"
+#endif
+
+#include "nsBidiUtils.h"
+#include "nsBidiPresUtils.h"
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+
+class nsAccessKeyInfo
+{
+public:
+    int32_t mAccesskeyIndex;
+    nscoord mBeforeWidth, mAccessWidth, mAccessUnderlineSize, mAccessOffset;
+};
+
+
+bool nsTextBoxFrame::gAlwaysAppendAccessKey          = false;
+bool nsTextBoxFrame::gAccessKeyPrefInitialized       = false;
+bool nsTextBoxFrame::gInsertSeparatorBeforeAccessKey = false;
+bool nsTextBoxFrame::gInsertSeparatorPrefInitialized = false;
+
+nsIFrame*
+NS_NewTextBoxFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+    return new (aPresShell) nsTextBoxFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsTextBoxFrame)
+
+NS_QUERYFRAME_HEAD(nsTextBoxFrame)
+  NS_QUERYFRAME_ENTRY(nsTextBoxFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsLeafBoxFrame)
+
+nsresult
+nsTextBoxFrame::AttributeChanged(int32_t         aNameSpaceID,
+                                 nsIAtom*        aAttribute,
+                                 int32_t         aModType)
+{
+    bool aResize;
+    bool aRedraw;
+
+    UpdateAttributes(aAttribute, aResize, aRedraw);
+
+    if (aResize) {
+        PresContext()->PresShell()->
+            FrameNeedsReflow(this, nsIPresShell::eStyleChange,
+                             NS_FRAME_IS_DIRTY);
+    } else if (aRedraw) {
+        nsBoxLayoutState state(PresContext());
+        XULRedraw(state);
+    }
+
+    // If the accesskey changed, register for the new value
+    // The old value has been unregistered in nsXULElement::SetAttr
+    if (aAttribute == nsGkAtoms::accesskey || aAttribute == nsGkAtoms::control)
+        RegUnregAccessKey(true);
+
+    return NS_OK;
+}
+
+nsTextBoxFrame::nsTextBoxFrame(nsStyleContext* aContext):
+  nsLeafBoxFrame(aContext), mAccessKeyInfo(nullptr), mCropType(CropRight),
+  mNeedsReflowCallback(false)
+{
+    MarkIntrinsicISizesDirty();
+}
+
+nsTextBoxFrame::~nsTextBoxFrame()
+{
+    delete mAccessKeyInfo;
+}
+
+
+void
+nsTextBoxFrame::Init(nsIContent*       aContent,
+                     nsContainerFrame* aParent,
+                     nsIFrame*         aPrevInFlow)
+{
+    nsLeafBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+    bool aResize;
+    bool aRedraw;
+    UpdateAttributes(nullptr, aResize, aRedraw); /* update all */
+
+    // register access key
+    RegUnregAccessKey(true);
+}
+
+void
+nsTextBoxFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+    // unregister access key
+    RegUnregAccessKey(false);
+    nsLeafBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+bool
+nsTextBoxFrame::AlwaysAppendAccessKey()
+{
+  if (!gAccessKeyPrefInitialized) 
+  {
+    gAccessKeyPrefInitialized = true;
+
+    const char* prefName = "intl.menuitems.alwaysappendaccesskeys";
+    nsAdoptingString val = Preferences::GetLocalizedString(prefName);
+    gAlwaysAppendAccessKey = val.EqualsLiteral("true");
+  }
+  return gAlwaysAppendAccessKey;
+}
+
+bool
+nsTextBoxFrame::InsertSeparatorBeforeAccessKey()
+{
+  if (!gInsertSeparatorPrefInitialized)
+  {
+    gInsertSeparatorPrefInitialized = true;
+
+    const char* prefName = "intl.menuitems.insertseparatorbeforeaccesskeys";
+    nsAdoptingString val = Preferences::GetLocalizedString(prefName);
+    gInsertSeparatorBeforeAccessKey = val.EqualsLiteral("true");
+  }
+  return gInsertSeparatorBeforeAccessKey;
+}
+
+class nsAsyncAccesskeyUpdate final : public nsIReflowCallback
+{
+public:
+    explicit nsAsyncAccesskeyUpdate(nsIFrame* aFrame) : mWeakFrame(aFrame)
+    {
+    }
+
+    virtual bool ReflowFinished() override
+    {
+        bool shouldFlush = false;
+        nsTextBoxFrame* frame =
+            static_cast<nsTextBoxFrame*>(mWeakFrame.GetFrame());
+        if (frame) {
+            shouldFlush = frame->UpdateAccesskey(mWeakFrame);
+        }
+        delete this;
+        return shouldFlush;
+    }
+
+    virtual void ReflowCallbackCanceled() override
+    {
+        delete this;
+    }
+
+    nsWeakFrame mWeakFrame;
+};
+
+bool
+nsTextBoxFrame::UpdateAccesskey(nsWeakFrame& aWeakThis)
+{
+    nsAutoString accesskey;
+    nsCOMPtr<nsIDOMXULLabelElement> labelElement = do_QueryInterface(mContent);
+    NS_ENSURE_TRUE(aWeakThis.IsAlive(), false);
+    if (labelElement) {
+        // Accesskey may be stored on control.
+        labelElement->GetAccessKey(accesskey);
+        NS_ENSURE_TRUE(aWeakThis.IsAlive(), false);
+    }
+    else {
+        mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, accesskey);
+    }
+
+    if (!accesskey.Equals(mAccessKey)) {
+        // Need to get clean mTitle.
+        RecomputeTitle();
+        mAccessKey = accesskey;
+        UpdateAccessTitle();
+        PresContext()->PresShell()->
+            FrameNeedsReflow(this, nsIPresShell::eStyleChange,
+                             NS_FRAME_IS_DIRTY);
+        return true;
+    }
+    return false;
+}
+
+void
+nsTextBoxFrame::UpdateAttributes(nsIAtom*         aAttribute,
+                                 bool&          aResize,
+                                 bool&          aRedraw)
+{
+    bool doUpdateTitle = false;
+    aResize = false;
+    aRedraw = false;
+
+    if (aAttribute == nullptr || aAttribute == nsGkAtoms::crop) {
+        static nsIContent::AttrValuesArray strings[] =
+          {&nsGkAtoms::left, &nsGkAtoms::start, &nsGkAtoms::center,
+           &nsGkAtoms::right, &nsGkAtoms::end, &nsGkAtoms::none, nullptr};
+        CroppingStyle cropType;
+        switch (mContent->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::crop,
+                                          strings, eCaseMatters)) {
+          case 0:
+          case 1:
+            cropType = CropLeft;
+            break;
+          case 2:
+            cropType = CropCenter;
+            break;
+          case 3:
+          case 4:
+            cropType = CropRight;
+            break;
+          case 5:
+            cropType = CropNone;
+            break;
+          default:
+            cropType = CropAuto;
+            break;
+        }
+
+        if (cropType != mCropType) {
+            aResize = true;
+            mCropType = cropType;
+        }
+    }
+
+    if (aAttribute == nullptr || aAttribute == nsGkAtoms::value) {
+        RecomputeTitle();
+        doUpdateTitle = true;
+    }
+
+    if (aAttribute == nullptr || aAttribute == nsGkAtoms::accesskey) {
+        mNeedsReflowCallback = true;
+        // Ensure that layout is refreshed and reflow callback called.
+        aResize = true;
+    }
+
+    if (doUpdateTitle) {
+        UpdateAccessTitle();
+        aResize = true;
+    }
+
+}
+
+class nsDisplayXULTextBox : public nsDisplayItem {
+public:
+  nsDisplayXULTextBox(nsDisplayListBuilder* aBuilder,
+                      nsTextBoxFrame* aFrame) :
+    nsDisplayItem(aBuilder, aFrame),
+    mDisableSubpixelAA(false)
+  {
+    MOZ_COUNT_CTOR(nsDisplayXULTextBox);
+  }
+#ifdef NS_BUILD_REFCNT_LOGGING
+  virtual ~nsDisplayXULTextBox() {
+    MOZ_COUNT_DTOR(nsDisplayXULTextBox);
+  }
+#endif
+
+  virtual void Paint(nsDisplayListBuilder* aBuilder,
+                     nsRenderingContext* aCtx) override;
+  virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder,
+                           bool* aSnap) override;
+  NS_DISPLAY_DECL_NAME("XULTextBox", TYPE_XUL_TEXT_BOX)
+
+  virtual nsRect GetComponentAlphaBounds(nsDisplayListBuilder* aBuilder) override;
+
+  virtual void DisableComponentAlpha() override {
+    mDisableSubpixelAA = true;
+  }
+
+  void PaintTextToContext(nsRenderingContext* aCtx,
+                          nsPoint aOffset,
+                          const nscolor* aColor);
+
+  bool mDisableSubpixelAA;
+};
+
+static void
+PaintTextShadowCallback(nsRenderingContext* aCtx,
+                        nsPoint aShadowOffset,
+                        const nscolor& aShadowColor,
+                        void* aData)
+{
+  reinterpret_cast<nsDisplayXULTextBox*>(aData)->
+           PaintTextToContext(aCtx, aShadowOffset, &aShadowColor);
+}
+
+void
+nsDisplayXULTextBox::Paint(nsDisplayListBuilder* aBuilder,
+                           nsRenderingContext* aCtx)
+{
+  DrawTargetAutoDisableSubpixelAntialiasing disable(aCtx->GetDrawTarget(),
+                                                    mDisableSubpixelAA);
+
+  // Paint the text shadow before doing any foreground stuff
+  nsRect drawRect = static_cast<nsTextBoxFrame*>(mFrame)->mTextDrawRect +
+                    ToReferenceFrame();
+  nsLayoutUtils::PaintTextShadow(mFrame, aCtx,
+                                 drawRect, mVisibleRect,
+                                 mFrame->StyleColor()->mColor,
+                                 PaintTextShadowCallback,
+                                 (void*)this);
+
+  PaintTextToContext(aCtx, nsPoint(0, 0), nullptr);
+}
+
+void
+nsDisplayXULTextBox::PaintTextToContext(nsRenderingContext* aCtx,
+                                        nsPoint aOffset,
+                                        const nscolor* aColor)
+{
+  static_cast<nsTextBoxFrame*>(mFrame)->
+    PaintTitle(*aCtx, mVisibleRect, ToReferenceFrame() + aOffset, aColor);
+}
+
+nsRect
+nsDisplayXULTextBox::GetBounds(nsDisplayListBuilder* aBuilder, bool* aSnap) {
+  *aSnap = false;
+  return mFrame->GetVisualOverflowRectRelativeToSelf() + ToReferenceFrame();
+}
+
+nsRect
+nsDisplayXULTextBox::GetComponentAlphaBounds(nsDisplayListBuilder* aBuilder)
+{
+  return static_cast<nsTextBoxFrame*>(mFrame)->GetComponentAlphaBounds() +
+      ToReferenceFrame();
+}
+
+void
+nsTextBoxFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                 const nsRect&           aDirtyRect,
+                                 const nsDisplayListSet& aLists)
+{
+    if (!IsVisibleForPainting(aBuilder))
+        return;
+
+    nsLeafBoxFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);
+    
+    aLists.Content()->AppendNewToTop(new (aBuilder)
+        nsDisplayXULTextBox(aBuilder, this));
+}
+
+void
+nsTextBoxFrame::PaintTitle(nsRenderingContext& aRenderingContext,
+                           const nsRect&        aDirtyRect,
+                           nsPoint              aPt,
+                           const nscolor*       aOverrideColor)
+{
+    if (mTitle.IsEmpty())
+        return;
+
+    DrawText(aRenderingContext, aDirtyRect, mTextDrawRect + aPt, aOverrideColor);
+}
+
+void
+nsTextBoxFrame::DrawText(nsRenderingContext& aRenderingContext,
+                         const nsRect&       aDirtyRect,
+                         const nsRect&       aTextRect,
+                         const nscolor*      aOverrideColor)
+{
+    nsPresContext* presContext = PresContext();
+    int32_t appUnitsPerDevPixel = presContext->AppUnitsPerDevPixel();
+    DrawTarget* drawTarget = aRenderingContext.GetDrawTarget();
+
+    // paint the title
+    nscolor overColor = 0;
+    nscolor underColor = 0;
+    nscolor strikeColor = 0;
+    uint8_t overStyle = 0;
+    uint8_t underStyle = 0;
+    uint8_t strikeStyle = 0;
+
+    // Begin with no decorations
+    uint8_t decorations = NS_STYLE_TEXT_DECORATION_LINE_NONE;
+    // A mask of all possible decorations.
+    uint8_t decorMask = NS_STYLE_TEXT_DECORATION_LINE_LINES_MASK;
+
+    WritingMode wm = GetWritingMode();
+    bool vertical = wm.IsVertical();
+
+    nsIFrame* f = this;
+    do {  // find decoration colors
+      nsStyleContext* context = f->StyleContext();
+      if (!context->HasTextDecorationLines()) {
+        break;
+      }
+      const nsStyleTextReset* styleText = context->StyleTextReset();
+
+      if (decorMask & styleText->mTextDecorationLine) {  // a decoration defined here
+        nscolor color;
+        if (aOverrideColor) {
+          color = *aOverrideColor;
+        } else {
+          color = context->StyleColor()->
+            CalcComplexColor(styleText->mTextDecorationColor);
+        }
+        uint8_t style = styleText->mTextDecorationStyle;
+
+        if (NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE & decorMask &
+              styleText->mTextDecorationLine) {
+          underColor = color;
+          underStyle = style;
+          decorMask &= ~NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
+          decorations |= NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
+        }
+        if (NS_STYLE_TEXT_DECORATION_LINE_OVERLINE & decorMask &
+              styleText->mTextDecorationLine) {
+          overColor = color;
+          overStyle = style;
+          decorMask &= ~NS_STYLE_TEXT_DECORATION_LINE_OVERLINE;
+          decorations |= NS_STYLE_TEXT_DECORATION_LINE_OVERLINE;
+        }
+        if (NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH & decorMask &
+              styleText->mTextDecorationLine) {
+          strikeColor = color;
+          strikeStyle = style;
+          decorMask &= ~NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH;
+          decorations |= NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH;
+        }
+      }
+    } while (0 != decorMask &&
+             (f = nsLayoutUtils::GetParentOrPlaceholderFor(f)));
+
+    RefPtr<nsFontMetrics> fontMet =
+      nsLayoutUtils::GetFontMetricsForFrame(this, 1.0f);
+    fontMet->SetVertical(wm.IsVertical());
+    fontMet->SetTextOrientation(StyleVisibility()->mTextOrientation);
+
+    nscoord offset;
+    nscoord size;
+    nscoord ascent = fontMet->MaxAscent();
+
+    nsPoint baselinePt;
+    if (wm.IsVertical()) {
+      baselinePt.x =
+        presContext->RoundAppUnitsToNearestDevPixels(aTextRect.x +
+            (wm.IsVerticalRL() ? aTextRect.width - ascent : ascent));
+      baselinePt.y = aTextRect.y;
+    } else {
+      baselinePt.x = aTextRect.x;
+      baselinePt.y =
+        presContext->RoundAppUnitsToNearestDevPixels(aTextRect.y + ascent);
+    }
+
+    nsCSSRendering::PaintDecorationLineParams params;
+    params.dirtyRect = ToRect(presContext->AppUnitsToGfxUnits(aDirtyRect));
+    params.pt = Point(presContext->AppUnitsToGfxUnits(aTextRect.x),
+                      presContext->AppUnitsToGfxUnits(aTextRect.y));
+    params.icoordInFrame =
+      Float(PresContext()->AppUnitsToGfxUnits(mTextDrawRect.x));
+    params.lineSize = Size(presContext->AppUnitsToGfxUnits(aTextRect.width), 0);
+    params.ascent = presContext->AppUnitsToGfxUnits(ascent);
+    params.vertical = vertical;
+
+    // XXX todo: vertical-mode support for decorations not tested yet,
+    // probably won't be positioned correctly
+
+    // Underlines are drawn before overlines, and both before the text
+    // itself, per http://www.w3.org/TR/CSS21/zindex.html point 7.2.1.4.1.1.
+    // (We don't apply this rule to the access-key underline because we only
+    // find out where that is as a side effect of drawing the text, in the
+    // general case -- see below.)
+    if (decorations & (NS_STYLE_TEXT_DECORATION_LINE_OVERLINE |
+                       NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE)) {
+      fontMet->GetUnderline(offset, size);
+      params.lineSize.height = presContext->AppUnitsToGfxUnits(size);
+      if ((decorations & NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE) &&
+          underStyle != NS_STYLE_TEXT_DECORATION_STYLE_NONE) {
+        params.color = underColor;
+        params.offset = presContext->AppUnitsToGfxUnits(offset);
+        params.decoration = NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
+        params.style = underStyle;
+        nsCSSRendering::PaintDecorationLine(this, *drawTarget, params);
+      }
+      if ((decorations & NS_STYLE_TEXT_DECORATION_LINE_OVERLINE) &&
+          overStyle != NS_STYLE_TEXT_DECORATION_STYLE_NONE) {
+        params.color = overColor;
+        params.offset = params.ascent;
+        params.decoration = NS_STYLE_TEXT_DECORATION_LINE_OVERLINE;
+        params.style = overStyle;
+        nsCSSRendering::PaintDecorationLine(this, *drawTarget, params);
+      }
+    }
+
+    nsRenderingContext refContext(
+        PresContext()->PresShell()->CreateReferenceRenderingContext());
+    DrawTarget* refDrawTarget = refContext.GetDrawTarget();
+
+    CalculateUnderline(refDrawTarget, *fontMet);
+
+    nscolor c = aOverrideColor ? *aOverrideColor : StyleColor()->mColor;
+    ColorPattern color(ToDeviceColor(c));
+    aRenderingContext.ThebesContext()->SetColor(Color::FromABGR(c));
+
+    nsresult rv = NS_ERROR_FAILURE;
+
+    if (mState & NS_FRAME_IS_BIDI) {
+      presContext->SetBidiEnabled();
+      nsBidiLevel level = nsBidiPresUtils::BidiLevelFromStyle(StyleContext());
+      if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
+          // We let the RenderText function calculate the mnemonic's
+          // underline position for us.
+          nsBidiPositionResolve posResolve;
+          posResolve.logicalIndex = mAccessKeyInfo->mAccesskeyIndex;
+          rv = nsBidiPresUtils::RenderText(mCroppedTitle.get(), mCroppedTitle.Length(), level,
+                                           presContext, aRenderingContext,
+                                           refDrawTarget, *fontMet,
+                                           baselinePt.x, baselinePt.y,
+                                           &posResolve,
+                                           1);
+          mAccessKeyInfo->mBeforeWidth = posResolve.visualLeftTwips;
+          mAccessKeyInfo->mAccessWidth = posResolve.visualWidth;
+      }
+      else
+      {
+          rv = nsBidiPresUtils::RenderText(mCroppedTitle.get(), mCroppedTitle.Length(), level,
+                                           presContext, aRenderingContext,
+                                           refDrawTarget, *fontMet,
+                                           baselinePt.x, baselinePt.y);
+      }
+    }
+    if (NS_FAILED(rv)) {
+       fontMet->SetTextRunRTL(false);
+
+       if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
+           // In the simple (non-BiDi) case, we calculate the mnemonic's
+           // underline position by getting the text metric.
+           // XXX are attribute values always two byte?
+           if (mAccessKeyInfo->mAccesskeyIndex > 0)
+               mAccessKeyInfo->mBeforeWidth = nsLayoutUtils::
+                   AppUnitWidthOfString(mCroppedTitle.get(),
+                                        mAccessKeyInfo->mAccesskeyIndex,
+                                        *fontMet, refDrawTarget);
+           else
+               mAccessKeyInfo->mBeforeWidth = 0;
+       }
+
+       fontMet->DrawString(mCroppedTitle.get(), mCroppedTitle.Length(),
+                           baselinePt.x, baselinePt.y, &aRenderingContext,
+                           refDrawTarget);
+    }
+
+    if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
+      nsRect r(aTextRect.x + mAccessKeyInfo->mBeforeWidth,
+               aTextRect.y + mAccessKeyInfo->mAccessOffset,
+               mAccessKeyInfo->mAccessWidth,
+               mAccessKeyInfo->mAccessUnderlineSize);
+      Rect devPxRect =
+        NSRectToSnappedRect(r, appUnitsPerDevPixel, *drawTarget);
+      drawTarget->FillRect(devPxRect, color);
+    }
+
+    // Strikeout is drawn on top of the text, per
+    // http://www.w3.org/TR/CSS21/zindex.html point 7.2.1.4.1.1.
+    if ((decorations & NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH) &&
+        strikeStyle != NS_STYLE_TEXT_DECORATION_STYLE_NONE) {
+      fontMet->GetStrikeout(offset, size);
+      params.color = strikeColor;
+      params.lineSize.height = presContext->AppUnitsToGfxUnits(size);
+      params.offset = presContext->AppUnitsToGfxUnits(offset);
+      params.decoration = NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH;
+      params.style = strikeStyle;
+      nsCSSRendering::PaintDecorationLine(this, *drawTarget, params);
+    }
+}
+
+void
+nsTextBoxFrame::CalculateUnderline(DrawTarget* aDrawTarget,
+                                   nsFontMetrics& aFontMetrics)
+{
+    if (mAccessKeyInfo && mAccessKeyInfo->mAccesskeyIndex != kNotFound) {
+         // Calculate all fields of mAccessKeyInfo which
+         // are the same for both BiDi and non-BiDi frames.
+         const char16_t *titleString = mCroppedTitle.get();
+         aFontMetrics.SetTextRunRTL(false);
+         mAccessKeyInfo->mAccessWidth = nsLayoutUtils::
+             AppUnitWidthOfString(titleString[mAccessKeyInfo->mAccesskeyIndex],
+                                  aFontMetrics, aDrawTarget);
+
+         nscoord offset, baseline;
+         aFontMetrics.GetUnderline(offset, mAccessKeyInfo->mAccessUnderlineSize);
+         baseline = aFontMetrics.MaxAscent();
+         mAccessKeyInfo->mAccessOffset = baseline - offset;
+    }
+}
+
+nscoord
+nsTextBoxFrame::CalculateTitleForWidth(nsRenderingContext& aRenderingContext,
+                                       nscoord              aWidth)
+{
+    DrawTarget* drawTarget = aRenderingContext.GetDrawTarget();
+
+    if (mTitle.IsEmpty()) {
+        mCroppedTitle.Truncate();
+        return 0;
+    }
+
+    RefPtr<nsFontMetrics> fm =
+      nsLayoutUtils::GetFontMetricsForFrame(this, 1.0f);
+
+    // see if the text will completely fit in the width given
+    nscoord titleWidth =
+      nsLayoutUtils::AppUnitWidthOfStringBidi(mTitle, this, *fm,
+                                              aRenderingContext);
+    if (titleWidth <= aWidth) {
+        mCroppedTitle = mTitle;
+        if (HasRTLChars(mTitle) ||
+            StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL) {
+            mState |= NS_FRAME_IS_BIDI;
+        }
+        return titleWidth;  // fits, done.
+    }
+
+    const nsDependentString& kEllipsis = nsContentUtils::GetLocalizedEllipsis();
+    if (mCropType != CropNone) {
+      // start with an ellipsis
+      mCroppedTitle.Assign(kEllipsis);
+
+      // see if the width is even smaller than the ellipsis
+      // if so, clear the text (XXX set as many '.' as we can?).
+      fm->SetTextRunRTL(false);
+      titleWidth = nsLayoutUtils::AppUnitWidthOfString(kEllipsis, *fm,
+                                                       drawTarget);
+
+      if (titleWidth > aWidth) {
+          mCroppedTitle.SetLength(0);
+          return 0;
+      }
+
+      // if the ellipsis fits perfectly, no use in trying to insert
+      if (titleWidth == aWidth)
+          return titleWidth;
+
+      aWidth -= titleWidth;
+    } else {
+      mCroppedTitle.Truncate(0);
+      titleWidth = 0;
+    }
+
+    using mozilla::unicode::ClusterIterator;
+    using mozilla::unicode::ClusterReverseIterator;
+
+    // ok crop things
+    switch (mCropType)
+    {
+        case CropAuto:
+        case CropNone:
+        case CropRight:
+        {
+            ClusterIterator iter(mTitle.Data(), mTitle.Length());
+            const char16_t* dataBegin = iter;
+            const char16_t* pos = dataBegin;
+            nscoord charWidth;
+            nscoord totalWidth = 0;
+
+            while (!iter.AtEnd()) {
+                iter.Next();
+                const char16_t* nextPos = iter;
+                ptrdiff_t length = nextPos - pos;
+                charWidth = nsLayoutUtils::AppUnitWidthOfString(pos, length,
+                                                                *fm,
+                                                                drawTarget);
+                if (totalWidth + charWidth > aWidth) {
+                    break;
+                }
+
+                if (UCS2_CHAR_IS_BIDI(*pos)) {
+                    mState |= NS_FRAME_IS_BIDI;
+                }
+                pos = nextPos;
+                totalWidth += charWidth;
+            }
+
+            if (pos == dataBegin) {
+                return titleWidth;
+            }
+
+            // insert what character we can in.
+            nsAutoString title(mTitle);
+            title.Truncate(pos - dataBegin);
+            mCroppedTitle.Insert(title, 0);
+        }
+        break;
+
+        case CropLeft:
+        {
+            ClusterReverseIterator iter(mTitle.Data(), mTitle.Length());
+            const char16_t* dataEnd = iter;
+            const char16_t* prevPos = dataEnd;
+            nscoord charWidth;
+            nscoord totalWidth = 0;
+
+            while (!iter.AtEnd()) {
+                iter.Next();
+                const char16_t* pos = iter;
+                ptrdiff_t length = prevPos - pos;
+                charWidth = nsLayoutUtils::AppUnitWidthOfString(pos, length,
+                                                                *fm,
+                                                                drawTarget);
+                if (totalWidth + charWidth > aWidth) {
+                    break;
+                }
+
+                if (UCS2_CHAR_IS_BIDI(*pos)) {
+                    mState |= NS_FRAME_IS_BIDI;
+                }
+                prevPos = pos;
+                totalWidth += charWidth;
+            }
+
+            if (prevPos == dataEnd) {
+                return titleWidth;
+            }
+
+            nsAutoString copy;
+            mTitle.Right(copy, dataEnd - prevPos);
+            mCroppedTitle += copy;
+        }
+        break;
+
+        case CropCenter:
+        {
+            nscoord stringWidth =
+                nsLayoutUtils::AppUnitWidthOfStringBidi(mTitle, this, *fm,
+                                                        aRenderingContext);
+            if (stringWidth <= aWidth) {
+                // the entire string will fit in the maximum width
+                mCroppedTitle.Insert(mTitle, 0);
+                break;
+            }
+
+            // determine how much of the string will fit in the max width
+            nscoord charWidth = 0;
+            nscoord totalWidth = 0;
+            ClusterIterator leftIter(mTitle.Data(), mTitle.Length());
+            ClusterReverseIterator rightIter(mTitle.Data(), mTitle.Length());
+            const char16_t* dataBegin = leftIter;
+            const char16_t* dataEnd = rightIter;
+            const char16_t* leftPos = dataBegin;
+            const char16_t* rightPos = dataEnd;
+            const char16_t* pos;
+            ptrdiff_t length;
+            nsAutoString leftString, rightString;
+
+            while (leftPos < rightPos) {
+                leftIter.Next();
+                pos = leftIter;
+                length = pos - leftPos;
+                charWidth = nsLayoutUtils::AppUnitWidthOfString(leftPos, length,
+                                                                *fm,
+                                                                drawTarget);
+                if (totalWidth + charWidth > aWidth) {
+                    break;
+                }
+
+                if (UCS2_CHAR_IS_BIDI(*leftPos)) {
+                    mState |= NS_FRAME_IS_BIDI;
+                }
+
+                leftString.Append(leftPos, length);
+                leftPos = pos;
+                totalWidth += charWidth;
+
+                if (leftPos >= rightPos) {
+                    break;
+                }
+
+                rightIter.Next();
+                pos = rightIter;
+                length = rightPos - pos;
+                charWidth = nsLayoutUtils::AppUnitWidthOfString(pos, length,
+                                                                *fm,
+                                                                drawTarget);
+                if (totalWidth + charWidth > aWidth) {
+                    break;
+                }
+
+                if (UCS2_CHAR_IS_BIDI(*pos)) {
+                    mState |= NS_FRAME_IS_BIDI;
+                }
+
+                rightString.Insert(pos, 0, length);
+                rightPos = pos;
+                totalWidth += charWidth;
+            }
+
+            mCroppedTitle = leftString + kEllipsis + rightString;
+        }
+        break;
+    }
+
+    return nsLayoutUtils::AppUnitWidthOfStringBidi(mCroppedTitle, this, *fm,
+                                                   aRenderingContext);
+}
+
+#define OLD_ELLIPSIS NS_LITERAL_STRING("...")
+
+// the following block is to append the accesskey to mTitle if there is an accesskey
+// but the mTitle doesn't have the character
+void
+nsTextBoxFrame::UpdateAccessTitle()
+{
+    /*
+     * Note that if you change appending access key label spec,
+     * you need to maintain same logic in following methods. See bug 324159.
+     * toolkit/content/commonDialog.js (setLabelForNode)
+     * toolkit/content/widgets/text.xml (formatAccessKey)
+     */
+    int32_t menuAccessKey;
+    nsMenuBarListener::GetMenuAccessKey(&menuAccessKey);
+    if (!menuAccessKey || mAccessKey.IsEmpty())
+        return;
+
+    if (!AlwaysAppendAccessKey() &&
+        FindInReadable(mAccessKey, mTitle, nsCaseInsensitiveStringComparator()))
+        return;
+
+    nsAutoString accessKeyLabel;
+    accessKeyLabel += '(';
+    accessKeyLabel += mAccessKey;
+    ToUpperCase(accessKeyLabel);
+    accessKeyLabel += ')';
+
+    if (mTitle.IsEmpty()) {
+        mTitle = accessKeyLabel;
+        return;
+    }
+
+    const nsDependentString& kEllipsis = nsContentUtils::GetLocalizedEllipsis();
+    uint32_t offset = mTitle.Length();
+    if (StringEndsWith(mTitle, kEllipsis)) {
+        offset -= kEllipsis.Length();
+    } else if (StringEndsWith(mTitle, OLD_ELLIPSIS)) {
+        // Try to check with our old ellipsis (for old addons)
+        offset -= OLD_ELLIPSIS.Length();
+    } else {
+        // Try to check with
+        // our default ellipsis (for non-localized addons) or ':'
+        const char16_t kLastChar = mTitle.Last();
+        if (kLastChar == char16_t(0x2026) || kLastChar == char16_t(':'))
+            offset--;
+    }
+
+    if (InsertSeparatorBeforeAccessKey() &&
+        offset > 0 && !NS_IS_SPACE(mTitle[offset - 1])) {
+        mTitle.Insert(' ', offset);
+        offset++;
+    }
+
+    mTitle.Insert(accessKeyLabel, offset);
+}
+
+void
+nsTextBoxFrame::UpdateAccessIndex()
+{
+    int32_t menuAccessKey;
+    nsMenuBarListener::GetMenuAccessKey(&menuAccessKey);
+    if (menuAccessKey) {
+        if (mAccessKey.IsEmpty()) {
+            if (mAccessKeyInfo) {
+                delete mAccessKeyInfo;
+                mAccessKeyInfo = nullptr;
+            }
+        } else {
+            if (!mAccessKeyInfo) {
+                mAccessKeyInfo = new nsAccessKeyInfo();
+                if (!mAccessKeyInfo)
+                    return;
+            }
+
+            nsAString::const_iterator start, end;
+                
+            mCroppedTitle.BeginReading(start);
+            mCroppedTitle.EndReading(end);
+            
+            // remember the beginning of the string
+            nsAString::const_iterator originalStart = start;
+
+            bool found;
+            if (!AlwaysAppendAccessKey()) {
+                // not appending access key - do case-sensitive search
+                // first
+                found = FindInReadable(mAccessKey, start, end);
+                if (!found) {
+                    // didn't find it - perform a case-insensitive search
+                    start = originalStart;
+                    found = FindInReadable(mAccessKey, start, end,
+                                           nsCaseInsensitiveStringComparator());
+                }
+            } else {
+                found = RFindInReadable(mAccessKey, start, end,
+                                        nsCaseInsensitiveStringComparator());
+            }
+            
+            if (found)
+                mAccessKeyInfo->mAccesskeyIndex = Distance(originalStart, start);
+            else
+                mAccessKeyInfo->mAccesskeyIndex = kNotFound;
+        }
+    }
+}
+
+void
+nsTextBoxFrame::RecomputeTitle()
+{
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::value, mTitle);
+
+  // This doesn't handle language-specific uppercasing/lowercasing
+  // rules, unlike textruns.
+  uint8_t textTransform = StyleText()->mTextTransform;
+  if (textTransform == NS_STYLE_TEXT_TRANSFORM_UPPERCASE) {
+    ToUpperCase(mTitle);
+  } else if (textTransform == NS_STYLE_TEXT_TRANSFORM_LOWERCASE) {
+    ToLowerCase(mTitle);
+  }
+  // We can't handle NS_STYLE_TEXT_TRANSFORM_CAPITALIZE because we
+  // have no clue about word boundaries here.  We also don't handle
+  // NS_STYLE_TEXT_TRANSFORM_FULL_WIDTH.
+}
+
+void
+nsTextBoxFrame::DidSetStyleContext(nsStyleContext* aOldStyleContext)
+{
+  if (!aOldStyleContext) {
+    // We're just being initialized
+    return;
+  }
+
+  const nsStyleText* oldTextStyle = aOldStyleContext->PeekStyleText();
+  // We should really have oldTextStyle here, since we asked for our
+  // nsStyleText during Init(), but if it's not there for some reason
+  // just assume the worst and recompute mTitle.
+  if (!oldTextStyle ||
+      oldTextStyle->mTextTransform != StyleText()->mTextTransform) {
+    RecomputeTitle();
+    UpdateAccessTitle();
+  }
+}
+
+NS_IMETHODIMP
+nsTextBoxFrame::DoXULLayout(nsBoxLayoutState& aBoxLayoutState)
+{
+    if (mNeedsReflowCallback) {
+        nsIReflowCallback* cb = new nsAsyncAccesskeyUpdate(this);
+        if (cb) {
+            PresContext()->PresShell()->PostReflowCallback(cb);
+        }
+        mNeedsReflowCallback = false;
+    }
+
+    nsresult rv = nsLeafBoxFrame::DoXULLayout(aBoxLayoutState);
+
+    CalcDrawRect(*aBoxLayoutState.GetRenderingContext());
+
+    const nsStyleText* textStyle = StyleText();
+    
+    nsRect scrollBounds(nsPoint(0, 0), GetSize());
+    nsRect textRect = mTextDrawRect;
+    
+    RefPtr<nsFontMetrics> fontMet =
+      nsLayoutUtils::GetFontMetricsForFrame(this, 1.0f);
+    nsBoundingMetrics metrics = 
+      fontMet->GetInkBoundsForVisualOverflow(mCroppedTitle.get(),
+                                             mCroppedTitle.Length(),
+                                             aBoxLayoutState.GetRenderingContext()->GetDrawTarget());
+
+    WritingMode wm = GetWritingMode();
+    LogicalRect tr(wm, textRect, GetSize());
+
+    tr.IStart(wm) -= metrics.leftBearing;
+    tr.ISize(wm) = metrics.width;
+    // In DrawText() we always draw with the baseline at MaxAscent() (relative to mTextDrawRect), 
+    tr.BStart(wm) += fontMet->MaxAscent() - metrics.ascent;
+    tr.BSize(wm) = metrics.ascent + metrics.descent;
+
+    textRect = tr.GetPhysicalRect(wm, GetSize());
+
+    // Our scrollable overflow is our bounds; our visual overflow may
+    // extend beyond that.
+    nsRect visualBounds;
+    visualBounds.UnionRect(scrollBounds, textRect);
+    nsOverflowAreas overflow(visualBounds, scrollBounds);
+
+    if (textStyle->mTextShadow) {
+      // text-shadow extends our visual but not scrollable bounds
+      nsRect &vis = overflow.VisualOverflow();
+      vis.UnionRect(vis, nsLayoutUtils::GetTextShadowRectsUnion(mTextDrawRect, this));
+    }
+    FinishAndStoreOverflow(overflow, GetSize());
+
+    return rv;
+}
+
+nsRect
+nsTextBoxFrame::GetComponentAlphaBounds()
+{
+  if (StyleText()->mTextShadow) {
+    return GetVisualOverflowRectRelativeToSelf();
+  }
+  return mTextDrawRect;
+}
+
+bool
+nsTextBoxFrame::ComputesOwnOverflowArea()
+{
+    return true;
+}
+
+/* virtual */ void
+nsTextBoxFrame::MarkIntrinsicISizesDirty()
+{
+    mNeedsRecalc = true;
+    nsLeafBoxFrame::MarkIntrinsicISizesDirty();
+}
+
+void
+nsTextBoxFrame::GetTextSize(nsRenderingContext& aRenderingContext,
+                            const nsString& aString,
+                            nsSize& aSize, nscoord& aAscent)
+{
+    RefPtr<nsFontMetrics> fontMet =
+      nsLayoutUtils::GetFontMetricsForFrame(this, 1.0f);
+    aSize.height = fontMet->MaxHeight();
+    aSize.width =
+      nsLayoutUtils::AppUnitWidthOfStringBidi(aString, this, *fontMet,
+                                              aRenderingContext);
+    aAscent = fontMet->MaxAscent();
+}
+
+void
+nsTextBoxFrame::CalcTextSize(nsBoxLayoutState& aBoxLayoutState)
+{
+    if (mNeedsRecalc) {
+        nsSize size;
+        nsRenderingContext* rendContext = aBoxLayoutState.GetRenderingContext();
+        if (rendContext) {
+            GetTextSize(*rendContext, mTitle, size, mAscent);
+            if (GetWritingMode().IsVertical()) {
+                Swap(size.width, size.height);
+            }
+            mTextSize = size;
+            mNeedsRecalc = false;
+        }
+    }
+}
+
+void
+nsTextBoxFrame::CalcDrawRect(nsRenderingContext &aRenderingContext)
+{
+    WritingMode wm = GetWritingMode();
+
+    LogicalRect textRect(wm, LogicalPoint(wm, 0, 0), GetLogicalSize(wm));
+    nsMargin borderPadding;
+    GetXULBorderAndPadding(borderPadding);
+    textRect.Deflate(wm, LogicalMargin(wm, borderPadding));
+
+    // determine (cropped) title and underline position
+    // determine (cropped) title which fits in aRect, and its width
+    // (where "width" is the text measure along its baseline, i.e. actually
+    // a physical height in vertical writing modes)
+    nscoord titleWidth =
+        CalculateTitleForWidth(aRenderingContext, textRect.ISize(wm));
+
+#ifdef ACCESSIBILITY
+    // Make sure to update the accessible tree in case when cropped title is
+    // changed.
+    nsAccessibilityService* accService = GetAccService();
+    if (accService) {
+        accService->UpdateLabelValue(PresContext()->PresShell(), mContent,
+                                     mCroppedTitle);
+    }
+#endif
+
+    // determine if and at which position to put the underline
+    UpdateAccessIndex();
+
+    // make the rect as small as our (cropped) text.
+    nscoord outerISize = textRect.ISize(wm);
+    textRect.ISize(wm) = titleWidth;
+
+    // Align our text within the overall rect by checking our text-align property.
+    const nsStyleText* textStyle = StyleText();
+    if (textStyle->mTextAlign == NS_STYLE_TEXT_ALIGN_CENTER) {
+      textRect.IStart(wm) += (outerISize - textRect.ISize(wm)) / 2;
+    } else if (textStyle->mTextAlign == NS_STYLE_TEXT_ALIGN_END ||
+             (textStyle->mTextAlign == NS_STYLE_TEXT_ALIGN_LEFT &&
+              !wm.IsBidiLTR()) ||
+             (textStyle->mTextAlign == NS_STYLE_TEXT_ALIGN_RIGHT &&
+              wm.IsBidiLTR())) {
+      textRect.IStart(wm) += (outerISize - textRect.ISize(wm));
+    }
+
+    mTextDrawRect = textRect.GetPhysicalRect(wm, GetSize());
+}
+
+/**
+ * Ok return our dimensions
+ */
+nsSize
+nsTextBoxFrame::GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState)
+{
+    CalcTextSize(aBoxLayoutState);
+
+    nsSize size = mTextSize;
+    DISPLAY_PREF_SIZE(this, size);
+
+    AddBorderAndPadding(size);
+    bool widthSet, heightSet;
+    nsIFrame::AddXULPrefSize(this, size, widthSet, heightSet);
+
+    return size;
+}
+
+/**
+ * Ok return our dimensions
+ */
+nsSize
+nsTextBoxFrame::GetXULMinSize(nsBoxLayoutState& aBoxLayoutState)
+{
+    CalcTextSize(aBoxLayoutState);
+
+    nsSize size = mTextSize;
+    DISPLAY_MIN_SIZE(this, size);
+
+    // if there is cropping our min width becomes our border and padding
+    if (mCropType != CropNone && mCropType != CropAuto) {
+        if (GetWritingMode().IsVertical()) {
+            size.height = 0;
+        } else {
+            size.width = 0;
+        }
+    }
+
+    AddBorderAndPadding(size);
+    bool widthSet, heightSet;
+    nsIFrame::AddXULMinSize(aBoxLayoutState, this, size, widthSet, heightSet);
+
+    return size;
+}
+
+nscoord
+nsTextBoxFrame::GetXULBoxAscent(nsBoxLayoutState& aBoxLayoutState)
+{
+    CalcTextSize(aBoxLayoutState);
+
+    nscoord ascent = mAscent;
+
+    nsMargin m(0,0,0,0);
+    GetXULBorderAndPadding(m);
+
+    WritingMode wm = GetWritingMode();
+    ascent += LogicalMargin(wm, m).BStart(wm);
+
+    return ascent;
+}
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+nsTextBoxFrame::GetFrameName(nsAString& aResult) const
+{
+    MakeFrameName(NS_LITERAL_STRING("TextBox"), aResult);
+    aResult += NS_LITERAL_STRING("[value=") + mTitle + NS_LITERAL_STRING("]");
+    return NS_OK;
+}
+#endif
+
+// If you make changes to this function, check its counterparts 
+// in nsBoxFrame and nsXULLabelFrame
+nsresult
+nsTextBoxFrame::RegUnregAccessKey(bool aDoReg)
+{
+    // if we have no content, we can't do anything
+    if (!mContent)
+        return NS_ERROR_FAILURE;
+
+    // check if we have a |control| attribute
+    // do this check first because few elements have control attributes, and we
+    // can weed out most of the elements quickly.
+
+    // XXXjag a side-effect is that we filter out anonymous <label>s
+    // in e.g. <menu>, <menuitem>, <button>. These <label>s inherit
+    // |accesskey| and would otherwise register themselves, overwriting
+    // the content we really meant to be registered.
+    if (!mContent->HasAttr(kNameSpaceID_None, nsGkAtoms::control))
+        return NS_OK;
+
+    // see if we even have an access key
+    nsAutoString accessKey;
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, accessKey);
+
+    if (accessKey.IsEmpty())
+        return NS_OK;
+
+    // With a valid PresContext we can get the ESM 
+    // and (un)register the access key
+    EventStateManager* esm = PresContext()->EventStateManager();
+
+    uint32_t key = accessKey.First();
+    if (aDoReg)
+        esm->RegisterAccessKey(mContent, key);
+    else
+        esm->UnregisterAccessKey(mContent, key);
+
+    return NS_OK;
+}
diff --git a/layout/xul/nsTextBoxFrame.h b/layout/xul/nsTextBoxFrame.h
new file mode 100644
index 0000000000..ca1b887484
--- /dev/null
+++ b/layout/xul/nsTextBoxFrame.h
@@ -0,0 +1,134 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsTextBoxFrame_h___
+#define nsTextBoxFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsLeafBoxFrame.h"
+
+class nsAccessKeyInfo;
+class nsAsyncAccesskeyUpdate;
+class nsFontMetrics;
+
+class nsTextBoxFrame : public nsLeafBoxFrame
+{
+public:
+  NS_DECL_QUERYFRAME_TARGET(nsTextBoxFrame)
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  virtual nsSize GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nsSize GetXULMinSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual nscoord GetXULBoxAscent(nsBoxLayoutState& aBoxLayoutState) override;
+  NS_IMETHOD DoXULLayout(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual void MarkIntrinsicISizesDirty() override;
+
+  enum CroppingStyle { CropNone, CropLeft, CropRight, CropCenter, CropAuto };
+
+  friend nsIFrame* NS_NewTextBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         asPrevInFlow) override;
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual nsresult AttributeChanged(int32_t         aNameSpaceID,
+                                    nsIAtom*        aAttribute,
+                                    int32_t         aModType) override;
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override;
+#endif
+
+  void UpdateAttributes(nsIAtom*         aAttribute,
+                        bool&          aResize,
+                        bool&          aRedraw);
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+
+  virtual ~nsTextBoxFrame();
+
+  void PaintTitle(nsRenderingContext& aRenderingContext,
+                  const nsRect&        aDirtyRect,
+                  nsPoint              aPt,
+                  const nscolor*       aOverrideColor);
+
+  nsRect GetComponentAlphaBounds();
+
+  virtual bool ComputesOwnOverflowArea() override;
+
+  void GetCroppedTitle(nsString& aTitle) const { aTitle = mCroppedTitle; }
+
+  virtual void DidSetStyleContext(nsStyleContext* aOldStyleContext) override;
+
+protected:
+  friend class nsAsyncAccesskeyUpdate;
+  friend class nsDisplayXULTextBox;
+  // Should be called only by nsAsyncAccesskeyUpdate.
+  // Returns true if accesskey was updated.
+  bool UpdateAccesskey(nsWeakFrame& aWeakThis);
+  void UpdateAccessTitle();
+  void UpdateAccessIndex();
+
+  // Recompute our title, ignoring the access key but taking into
+  // account text-transform.
+  void RecomputeTitle();
+
+  // REVIEW: SORRY! Couldn't resist devirtualizing these
+  void LayoutTitle(nsPresContext*      aPresContext,
+                   nsRenderingContext& aRenderingContext,
+                   const nsRect&        aRect);
+
+  void CalculateUnderline(DrawTarget* aDrawTarget, nsFontMetrics& aFontMetrics);
+
+  void CalcTextSize(nsBoxLayoutState& aBoxLayoutState);
+
+  void CalcDrawRect(nsRenderingContext &aRenderingContext);
+
+  explicit nsTextBoxFrame(nsStyleContext* aContext);
+
+  nscoord CalculateTitleForWidth(nsRenderingContext& aRenderingContext,
+                                 nscoord              aWidth);
+
+  void GetTextSize(nsRenderingContext& aRenderingContext,
+                   const nsString&      aString,
+                   nsSize&              aSize,
+                   nscoord&             aAscent);
+
+  nsresult RegUnregAccessKey(bool aDoReg);
+
+private:
+
+  bool AlwaysAppendAccessKey();
+  bool InsertSeparatorBeforeAccessKey();
+
+  void DrawText(nsRenderingContext& aRenderingContext,
+                const nsRect&       aDirtyRect,
+                const nsRect&       aTextRect,
+                const nscolor*      aOverrideColor);
+
+  nsString mTitle;
+  nsString mCroppedTitle;
+  nsString mAccessKey;
+  nsSize mTextSize;
+  nsRect mTextDrawRect;
+  nsAccessKeyInfo* mAccessKeyInfo;
+
+  CroppingStyle mCropType;
+  nscoord mAscent;
+  bool mNeedsRecalc;
+  bool mNeedsReflowCallback;
+
+  static bool gAlwaysAppendAccessKey;
+  static bool gAccessKeyPrefInitialized;
+  static bool gInsertSeparatorBeforeAccessKey;
+  static bool gInsertSeparatorPrefInitialized;
+
+}; // class nsTextBoxFrame
+
+#endif /* nsTextBoxFrame_h___ */
diff --git a/layout/xul/nsTitleBarFrame.cpp b/layout/xul/nsTitleBarFrame.cpp
new file mode 100644
index 0000000000..2792403dcc
--- /dev/null
+++ b/layout/xul/nsTitleBarFrame.cpp
@@ -0,0 +1,172 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMPtr.h"
+#include "nsTitleBarFrame.h"
+#include "nsIContent.h"
+#include "nsIDocument.h"
+#include "nsIDOMNodeList.h"
+#include "nsGkAtoms.h"
+#include "nsIWidget.h"
+#include "nsMenuPopupFrame.h"
+#include "nsPresContext.h"
+#include "nsIDocShell.h"
+#include "nsPIDOMWindow.h"
+#include "nsDisplayList.h"
+#include "nsContentUtils.h"
+#include "mozilla/MouseEvents.h"
+
+using namespace mozilla;
+
+//
+// NS_NewTitleBarFrame
+//
+// Creates a new TitleBar frame and returns it
+//
+nsIFrame*
+NS_NewTitleBarFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsTitleBarFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsTitleBarFrame)
+
+nsTitleBarFrame::nsTitleBarFrame(nsStyleContext* aContext)
+:nsBoxFrame(aContext, false)
+{
+  mTrackingMouseMove = false;
+  UpdateMouseThrough();
+}
+
+void
+nsTitleBarFrame::BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                             const nsRect&           aDirtyRect,
+                                             const nsDisplayListSet& aLists)
+{
+  // override, since we don't want children to get events
+  if (aBuilder->IsForEventDelivery()) {
+    if (!mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::allowevents,
+                               nsGkAtoms::_true, eCaseMatters))
+      return;
+  }
+  nsBoxFrame::BuildDisplayListForChildren(aBuilder, aDirtyRect, aLists);
+}
+
+nsresult
+nsTitleBarFrame::HandleEvent(nsPresContext* aPresContext,
+                             WidgetGUIEvent* aEvent,
+                             nsEventStatus* aEventStatus)
+{
+  NS_ENSURE_ARG_POINTER(aEventStatus);
+  if (nsEventStatus_eConsumeNoDefault == *aEventStatus) {
+    return NS_OK;
+  }
+
+  bool doDefault = true;
+
+  switch (aEvent->mMessage) {
+
+   case eMouseDown: {
+       if (aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton) {
+         // titlebar has no effect in non-chrome shells
+         nsCOMPtr<nsIDocShellTreeItem> dsti = aPresContext->GetDocShell();
+         if (dsti) {
+           if (dsti->ItemType() == nsIDocShellTreeItem::typeChrome) {
+             // we're tracking.
+             mTrackingMouseMove = true;
+
+             // start capture.
+             nsIPresShell::SetCapturingContent(GetContent(), CAPTURE_IGNOREALLOWED);
+
+             // remember current mouse coordinates.
+             mLastPoint = aEvent->mRefPoint;
+           }
+         }
+
+         *aEventStatus = nsEventStatus_eConsumeNoDefault;
+         doDefault = false;
+       }
+     }
+     break;
+
+
+   case eMouseUp: {
+       if (mTrackingMouseMove &&
+           aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton) {
+         // we're done tracking.
+         mTrackingMouseMove = false;
+
+         // end capture
+         nsIPresShell::SetCapturingContent(nullptr, 0);
+
+         *aEventStatus = nsEventStatus_eConsumeNoDefault;
+         doDefault = false;
+       }
+     }
+     break;
+
+   case eMouseMove: {
+       if(mTrackingMouseMove)
+       {
+         LayoutDeviceIntPoint nsMoveBy = aEvent->mRefPoint - mLastPoint;
+
+         nsIFrame* parent = GetParent();
+         while (parent) {
+           nsMenuPopupFrame* popupFrame = do_QueryFrame(parent);
+           if (popupFrame)
+             break;
+           parent = parent->GetParent();
+         }
+
+         // if the titlebar is in a popup, move the popup frame, otherwise
+         // move the widget associated with the window
+         if (parent) {
+           nsMenuPopupFrame* menuPopupFrame = static_cast<nsMenuPopupFrame*>(parent);
+           nsCOMPtr<nsIWidget> widget = menuPopupFrame->GetWidget();
+           LayoutDeviceIntRect bounds = widget->GetScreenBounds();
+
+           CSSPoint cssPos = (bounds.TopLeft() + nsMoveBy)
+                           / aPresContext->CSSToDevPixelScale();
+           menuPopupFrame->MoveTo(RoundedToInt(cssPos), false);
+         }
+         else {
+           nsIPresShell* presShell = aPresContext->PresShell();
+           nsPIDOMWindowOuter *window = presShell->GetDocument()->GetWindow();
+           if (window) {
+             window->MoveBy(nsMoveBy.x, nsMoveBy.y);
+           }
+         }
+
+         *aEventStatus = nsEventStatus_eConsumeNoDefault;
+
+         doDefault = false;
+       }
+     }
+     break;
+
+    case eMouseClick: {
+      WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+      if (mouseEvent->IsLeftClickEvent()) {
+        MouseClicked(mouseEvent);
+      }
+      break;
+    }
+
+    default:
+      break;
+  }
+
+  if ( doDefault )
+    return nsBoxFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+  else
+    return NS_OK;
+}
+
+void
+nsTitleBarFrame::MouseClicked(WidgetMouseEvent* aEvent)
+{
+  // Execute the oncommand event handler.
+  nsContentUtils::DispatchXULCommand(mContent, aEvent && aEvent->IsTrusted());
+}
diff --git a/layout/xul/nsTitleBarFrame.h b/layout/xul/nsTitleBarFrame.h
new file mode 100644
index 0000000000..17279c578f
--- /dev/null
+++ b/layout/xul/nsTitleBarFrame.h
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef nsTitleBarFrame_h___
+#define nsTitleBarFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "mozilla/EventForwards.h"
+#include "nsBoxFrame.h"
+
+class nsTitleBarFrame : public nsBoxFrame  
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewTitleBarFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);  
+
+  explicit nsTitleBarFrame(nsStyleContext* aContext);
+
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) override;
+
+  virtual nsresult HandleEvent(nsPresContext* aPresContext,
+                               mozilla::WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  virtual void MouseClicked(mozilla::WidgetMouseEvent* aEvent);
+
+  void UpdateMouseThrough() override { AddStateBits(NS_FRAME_MOUSE_THROUGH_NEVER); }
+
+protected:
+  bool mTrackingMouseMove;
+  mozilla::LayoutDeviceIntPoint mLastPoint;
+
+}; // class nsTitleBarFrame
+
+#endif /* nsTitleBarFrame_h___ */
diff --git a/layout/xul/nsXULLabelFrame.cpp b/layout/xul/nsXULLabelFrame.cpp
new file mode 100644
index 0000000000..22b8754617
--- /dev/null
+++ b/layout/xul/nsXULLabelFrame.cpp
@@ -0,0 +1,116 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* derived class of nsBlockFrame used for xul:label elements */
+
+#include "mozilla/EventStateManager.h"
+#include "nsXULLabelFrame.h"
+#include "nsHTMLParts.h"
+#include "nsNameSpaceManager.h"
+
+using namespace mozilla;
+
+nsIFrame*
+NS_NewXULLabelFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  nsXULLabelFrame* it = new (aPresShell) nsXULLabelFrame(aContext);
+
+  it->AddStateBits(NS_BLOCK_FLOAT_MGR | NS_BLOCK_MARGIN_ROOT);
+
+  return it;
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsXULLabelFrame)
+
+// If you make changes to this function, check its counterparts 
+// in nsBoxFrame and nsTextBoxFrame
+nsresult
+nsXULLabelFrame::RegUnregAccessKey(bool aDoReg)
+{
+  // if we have no content, we can't do anything
+  if (!mContent)
+    return NS_ERROR_FAILURE;
+
+  // To filter out <label>s without a control attribute.
+  // XXXjag a side-effect is that we filter out anonymous <label>s
+  // in e.g. <menu>, <menuitem>, <button>. These <label>s inherit
+  // |accesskey| and would otherwise register themselves, overwriting
+  // the content we really meant to be registered.
+  if (!mContent->HasAttr(kNameSpaceID_None, nsGkAtoms::control))
+    return NS_OK;
+
+  nsAutoString accessKey;
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, accessKey);
+
+  if (accessKey.IsEmpty())
+    return NS_OK;
+
+  // With a valid PresContext we can get the ESM 
+  // and register the access key
+  EventStateManager* esm = PresContext()->EventStateManager();
+
+  uint32_t key = accessKey.First();
+  if (aDoReg)
+    esm->RegisterAccessKey(mContent, key);
+  else
+    esm->UnregisterAccessKey(mContent, key);
+
+  return NS_OK;
+}
+
+/////////////////////////////////////////////////////////////////////////////
+// nsIFrame
+
+void
+nsXULLabelFrame::Init(nsIContent*       aContent,
+                      nsContainerFrame* aParent,
+                      nsIFrame*         aPrevInFlow)
+{
+  nsBlockFrame::Init(aContent, aParent, aPrevInFlow);
+
+  // register access key
+  RegUnregAccessKey(true);
+}
+
+void
+nsXULLabelFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  // unregister access key
+  RegUnregAccessKey(false);
+  nsBlockFrame::DestroyFrom(aDestructRoot);
+} 
+
+nsresult
+nsXULLabelFrame::AttributeChanged(int32_t aNameSpaceID,
+                                  nsIAtom* aAttribute,
+                                  int32_t aModType)
+{
+  nsresult rv = nsBlockFrame::AttributeChanged(aNameSpaceID, 
+                                               aAttribute, aModType);
+
+  // If the accesskey changed, register for the new value
+  // The old value has been unregistered in nsXULElement::SetAttr
+  if (aAttribute == nsGkAtoms::accesskey || aAttribute == nsGkAtoms::control)
+    RegUnregAccessKey(true);
+
+  return rv;
+}
+
+nsIAtom*
+nsXULLabelFrame::GetType() const
+{
+  return nsGkAtoms::XULLabelFrame;
+}
+
+/////////////////////////////////////////////////////////////////////////////
+// Diagnostics
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult
+nsXULLabelFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("XULLabel"), aResult);
+}
+#endif
diff --git a/layout/xul/nsXULLabelFrame.h b/layout/xul/nsXULLabelFrame.h
new file mode 100644
index 0000000000..e97fc3fca3
--- /dev/null
+++ b/layout/xul/nsXULLabelFrame.h
@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* derived class of nsBlockFrame used for xul:label elements */
+
+#ifndef nsXULLabelFrame_h_
+#define nsXULLabelFrame_h_
+
+#include "mozilla/Attributes.h"
+#include "nsBlockFrame.h"
+
+#ifndef MOZ_XUL
+#error "This file should not be included"
+#endif
+
+class nsXULLabelFrame : public nsBlockFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewXULLabelFrame(nsIPresShell* aPresShell,
+                                       nsStyleContext *aContext);
+  
+  // nsIFrame
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+  /**
+   * Get the "type" of the frame
+   *
+   * @see nsGkAtoms::XULLabelFrame
+   */
+  virtual nsIAtom* GetType() const override;
+  
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const override;
+#endif
+
+protected:
+  explicit nsXULLabelFrame(nsStyleContext *aContext) : nsBlockFrame(aContext) {}
+
+  nsresult RegUnregAccessKey(bool aDoReg);
+};
+
+nsIFrame*
+NS_NewXULLabelFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+#endif /* !defined(nsXULLabelFrame_h_) */
diff --git a/layout/xul/nsXULPopupManager.cpp b/layout/xul/nsXULPopupManager.cpp
new file mode 100644
index 0000000000..6e8cc3dda1
--- /dev/null
+++ b/layout/xul/nsXULPopupManager.cpp
@@ -0,0 +1,2870 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsGkAtoms.h"
+#include "nsXULPopupManager.h"
+#include "nsMenuFrame.h"
+#include "nsMenuPopupFrame.h"
+#include "nsMenuBarFrame.h"
+#include "nsMenuBarListener.h"
+#include "nsContentUtils.h"
+#include "nsIDOMDocument.h"
+#include "nsIDOMEvent.h"
+#include "nsIDOMXULElement.h"
+#include "nsIDOMXULMenuListElement.h"
+#include "nsIXULDocument.h"
+#include "nsIXULTemplateBuilder.h"
+#include "nsCSSFrameConstructor.h"
+#include "nsGlobalWindow.h"
+#include "nsLayoutUtils.h"
+#include "nsViewManager.h"
+#include "nsIComponentManager.h"
+#include "nsITimer.h"
+#include "nsFocusManager.h"
+#include "nsIDocShell.h"
+#include "nsPIDOMWindow.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIBaseWindow.h"
+#include "nsIDOMKeyEvent.h"
+#include "nsIDOMMouseEvent.h"
+#include "nsCaret.h"
+#include "nsIDocument.h"
+#include "nsPIWindowRoot.h"
+#include "nsFrameManager.h"
+#include "nsIObserverService.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h" // for nsIDOMEvent::InternalDOMEvent()
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/EventStateManager.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/Services.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+static_assert(nsIDOMKeyEvent::DOM_VK_HOME  == nsIDOMKeyEvent::DOM_VK_END + 1 &&
+              nsIDOMKeyEvent::DOM_VK_LEFT  == nsIDOMKeyEvent::DOM_VK_END + 2 &&
+              nsIDOMKeyEvent::DOM_VK_UP    == nsIDOMKeyEvent::DOM_VK_END + 3 &&
+              nsIDOMKeyEvent::DOM_VK_RIGHT == nsIDOMKeyEvent::DOM_VK_END + 4 &&
+              nsIDOMKeyEvent::DOM_VK_DOWN  == nsIDOMKeyEvent::DOM_VK_END + 5,
+              "nsXULPopupManager assumes some keyCode values are consecutive");
+
+const nsNavigationDirection DirectionFromKeyCodeTable[2][6] = {
+  {
+    eNavigationDirection_Last,   // nsIDOMKeyEvent::DOM_VK_END
+    eNavigationDirection_First,  // nsIDOMKeyEvent::DOM_VK_HOME
+    eNavigationDirection_Start,  // nsIDOMKeyEvent::DOM_VK_LEFT
+    eNavigationDirection_Before, // nsIDOMKeyEvent::DOM_VK_UP
+    eNavigationDirection_End,    // nsIDOMKeyEvent::DOM_VK_RIGHT
+    eNavigationDirection_After   // nsIDOMKeyEvent::DOM_VK_DOWN
+  },
+  {
+    eNavigationDirection_Last,   // nsIDOMKeyEvent::DOM_VK_END
+    eNavigationDirection_First,  // nsIDOMKeyEvent::DOM_VK_HOME
+    eNavigationDirection_End,    // nsIDOMKeyEvent::DOM_VK_LEFT
+    eNavigationDirection_Before, // nsIDOMKeyEvent::DOM_VK_UP
+    eNavigationDirection_Start,  // nsIDOMKeyEvent::DOM_VK_RIGHT
+    eNavigationDirection_After   // nsIDOMKeyEvent::DOM_VK_DOWN
+  }
+};
+
+nsXULPopupManager* nsXULPopupManager::sInstance = nullptr;
+
+nsIContent* nsMenuChainItem::Content()
+{
+  return mFrame->GetContent();
+}
+
+void nsMenuChainItem::SetParent(nsMenuChainItem* aParent)
+{
+  if (mParent) {
+    NS_ASSERTION(mParent->mChild == this, "Unexpected - parent's child not set to this");
+    mParent->mChild = nullptr;
+  }
+  mParent = aParent;
+  if (mParent) {
+    if (mParent->mChild)
+      mParent->mChild->mParent = nullptr;
+    mParent->mChild = this;
+  }
+}
+
+void nsMenuChainItem::Detach(nsMenuChainItem** aRoot)
+{
+  // If the item has a child, set the child's parent to this item's parent,
+  // effectively removing the item from the chain. If the item has no child,
+  // just set the parent to null.
+  if (mChild) {
+    NS_ASSERTION(this != *aRoot, "Unexpected - popup with child at end of chain");
+    mChild->SetParent(mParent);
+  }
+  else {
+    // An item without a child should be the first item in the chain, so set
+    // the first item pointer, pointed to by aRoot, to the parent.
+    NS_ASSERTION(this == *aRoot, "Unexpected - popup with no child not at end of chain");
+    *aRoot = mParent;
+    SetParent(nullptr);
+  }
+}
+
+bool nsXULPopupManager::sDevtoolsDisableAutoHide = false;
+
+const char* kPrefDevtoolsDisableAutoHide =
+  "ui.popup.disable_autohide";
+
+NS_IMPL_ISUPPORTS(nsXULPopupManager,
+                  nsIDOMEventListener,
+                  nsITimerCallback,
+                  nsIObserver)
+
+nsXULPopupManager::nsXULPopupManager() :
+  mRangeOffset(0),
+  mCachedMousePoint(0, 0),
+  mCachedModifiers(0),
+  mActiveMenuBar(nullptr),
+  mPopups(nullptr),
+  mNoHidePanels(nullptr),
+  mTimerMenu(nullptr)
+{
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (obs) {
+    obs->AddObserver(this, "xpcom-shutdown", false);
+  }
+  Preferences::AddBoolVarCache(&sDevtoolsDisableAutoHide,
+                               kPrefDevtoolsDisableAutoHide, false);
+}
+
+nsXULPopupManager::~nsXULPopupManager() 
+{
+  NS_ASSERTION(!mPopups && !mNoHidePanels, "XUL popups still open");
+}
+
+nsresult
+nsXULPopupManager::Init()
+{
+  sInstance = new nsXULPopupManager();
+  NS_ENSURE_TRUE(sInstance, NS_ERROR_OUT_OF_MEMORY);
+  NS_ADDREF(sInstance);
+  return NS_OK;
+}
+
+void
+nsXULPopupManager::Shutdown()
+{
+  NS_IF_RELEASE(sInstance);
+}
+
+NS_IMETHODIMP
+nsXULPopupManager::Observe(nsISupports *aSubject,
+                           const char *aTopic,
+                           const char16_t *aData)
+{
+  if (!nsCRT::strcmp(aTopic, "xpcom-shutdown")) {
+    if (mKeyListener) {
+      mKeyListener->RemoveEventListener(NS_LITERAL_STRING("keypress"), this, true);
+      mKeyListener->RemoveEventListener(NS_LITERAL_STRING("keydown"), this, true);
+      mKeyListener->RemoveEventListener(NS_LITERAL_STRING("keyup"), this, true);
+      mKeyListener = nullptr;
+    }
+    mRangeParent = nullptr;
+    // mOpeningPopup is cleared explicitly soon after using it.
+    nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+    if (obs) {
+      obs->RemoveObserver(this, "xpcom-shutdown");
+    }
+  }
+
+  return NS_OK;
+}
+
+nsXULPopupManager*
+nsXULPopupManager::GetInstance()
+{
+  MOZ_ASSERT(sInstance);
+  return sInstance;
+}
+
+bool
+nsXULPopupManager::Rollup(uint32_t aCount, bool aFlush,
+                          const nsIntPoint* pos, nsIContent** aLastRolledUp)
+{
+  // We can disable the autohide behavior via a pref to ease debugging.
+  if (nsXULPopupManager::sDevtoolsDisableAutoHide) {
+    // Required on linux to allow events to work on other targets.
+    if (mWidget) {
+      mWidget->CaptureRollupEvents(nullptr, false);
+    }
+    return false;
+  }
+
+  bool consume = false;
+
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  if (item) {
+    if (aLastRolledUp) {
+      // We need to get the popup that will be closed last, so that widget can
+      // keep track of it so it doesn't reopen if a mousedown event is going to
+      // processed. Keep going up the menu chain to get the first level menu of
+      // the same type. If a different type is encountered it means we have,
+      // for example, a menulist or context menu inside a panel, and we want to
+      // treat these as distinct. It's possible that this menu doesn't end up
+      // closing because the popuphiding event was cancelled, but in that case
+      // we don't need to deal with the menu reopening as it will already still
+      // be open.
+      nsMenuChainItem* first = item;
+      while (first->GetParent()) {
+        nsMenuChainItem* parent = first->GetParent();
+        if (first->Frame()->PopupType() != parent->Frame()->PopupType() ||
+            first->IsContextMenu() != parent->IsContextMenu()) {
+          break;
+        }
+        first = parent;
+      }
+
+
+      *aLastRolledUp = first->Content();
+    }
+
+    ConsumeOutsideClicksResult consumeResult = item->Frame()->ConsumeOutsideClicks();
+    consume = (consumeResult == ConsumeOutsideClicks_True);
+
+    bool rollup = true;
+
+    // If norolluponanchor is true, then don't rollup when clicking the anchor.
+    // This would be used to allow adjusting the caret position in an
+    // autocomplete field without hiding the popup for example.
+    bool noRollupOnAnchor = (!consume && pos &&
+      item->Frame()->GetContent()->AttrValueIs(kNameSpaceID_None,
+        nsGkAtoms::norolluponanchor, nsGkAtoms::_true, eCaseMatters));
+
+    // When ConsumeOutsideClicks_ParentOnly is used, always consume the click
+    // when the click was over the anchor. This way, clicking on a menu doesn't
+    // reopen the menu.
+    if ((consumeResult == ConsumeOutsideClicks_ParentOnly || noRollupOnAnchor) && pos) {
+      nsMenuPopupFrame* popupFrame = item->Frame();
+      nsIntRect anchorRect;
+      if (popupFrame->IsAnchored()) {
+        // Check if the popup has a screen anchor rectangle. If not, get the rectangle
+        // from the anchor element.
+        anchorRect = popupFrame->GetScreenAnchorRect();
+        if (anchorRect.x == -1 || anchorRect.y == -1) {
+          nsCOMPtr<nsIContent> anchor = popupFrame->GetAnchor();
+
+          // Check if the anchor has indicated another node to use for checking
+          // for roll-up. That way, we can anchor a popup on anonymous content or
+          // an individual icon, while clicking elsewhere within a button or other
+          // container doesn't result in us re-opening the popup.
+          if (anchor) {
+            nsAutoString consumeAnchor;
+            anchor->GetAttr(kNameSpaceID_None, nsGkAtoms::consumeanchor,
+                            consumeAnchor);
+            if (!consumeAnchor.IsEmpty()) {
+              nsIDocument* doc = anchor->GetOwnerDocument();
+              nsIContent* newAnchor = doc->GetElementById(consumeAnchor);
+              if (newAnchor) {
+                anchor = newAnchor;
+              }
+            }
+          }
+
+          if (anchor && anchor->GetPrimaryFrame()) {
+            anchorRect = anchor->GetPrimaryFrame()->GetScreenRect();
+          }
+        }
+      }
+
+      // It's possible that some other element is above the anchor at the same
+      // position, but the only thing that would happen is that the mouse
+      // event will get consumed, so here only a quick coordinates check is
+      // done rather than a slower complete check of what is at that location.
+      nsPresContext* presContext = item->Frame()->PresContext();
+      nsIntPoint posCSSPixels(presContext->DevPixelsToIntCSSPixels(pos->x),
+                              presContext->DevPixelsToIntCSSPixels(pos->y));
+      if (anchorRect.Contains(posCSSPixels)) {
+        if (consumeResult == ConsumeOutsideClicks_ParentOnly) {
+          consume = true;
+        }
+
+        if (noRollupOnAnchor) {
+          rollup = false;
+        }
+      }
+    }
+
+    if (rollup) {
+      // if a number of popups to close has been specified, determine the last
+      // popup to close
+      nsIContent* lastPopup = nullptr;
+      if (aCount != UINT32_MAX) {
+        nsMenuChainItem* last = item;
+        while (--aCount && last->GetParent()) {
+          last = last->GetParent();
+        }
+        if (last) {
+          lastPopup = last->Content();
+        }
+      }
+
+      nsPresContext* presContext = item->Frame()->PresContext();
+      RefPtr<nsViewManager> viewManager = presContext->PresShell()->GetViewManager();
+
+      HidePopup(item->Content(), true, true, false, true, lastPopup);
+
+      if (aFlush) {
+        // The popup's visibility doesn't update until the minimize animation has
+        // finished, so call UpdateWidgetGeometry to update it right away.
+        viewManager->UpdateWidgetGeometry();
+      }
+    }
+  }
+
+  return consume;
+}
+
+////////////////////////////////////////////////////////////////////////
+bool nsXULPopupManager::ShouldRollupOnMouseWheelEvent()
+{
+  // should rollup only for autocomplete widgets
+  // XXXndeakin this should really be something the popup has more control over
+
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  if (!item)
+    return false;
+
+  nsIContent* content = item->Frame()->GetContent();
+  if (!content)
+    return false;
+
+  if (content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::rolluponmousewheel,
+                           nsGkAtoms::_true, eCaseMatters))
+    return true;
+
+  if (content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::rolluponmousewheel,
+                           nsGkAtoms::_false, eCaseMatters))
+    return false;
+
+  nsAutoString value;
+  content->GetAttr(kNameSpaceID_None, nsGkAtoms::type, value);
+  return StringBeginsWith(value, NS_LITERAL_STRING("autocomplete"));
+}
+
+bool nsXULPopupManager::ShouldConsumeOnMouseWheelEvent()
+{
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  if (!item)
+    return false;
+
+  nsMenuPopupFrame* frame = item->Frame();
+  if (frame->PopupType() != ePopupTypePanel)
+    return true;
+
+  nsIContent* content = frame->GetContent();
+  return !(content && content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                                           nsGkAtoms::arrow, eCaseMatters));
+}
+
+// a menu should not roll up if activated by a mouse activate message (eg. X-mouse)
+bool nsXULPopupManager::ShouldRollupOnMouseActivate()
+{
+  return false;
+}
+
+uint32_t
+nsXULPopupManager::GetSubmenuWidgetChain(nsTArray<nsIWidget*> *aWidgetChain)
+{
+  // this method is used by the widget code to determine the list of popups
+  // that are open. If a mouse click occurs outside one of these popups, the
+  // panels will roll up. If the click is inside a popup, they will not roll up
+  uint32_t count = 0, sameTypeCount = 0;
+
+  NS_ASSERTION(aWidgetChain, "null parameter");
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  while (item) {
+    nsCOMPtr<nsIWidget> widget = item->Frame()->GetWidget();
+    NS_ASSERTION(widget, "open popup has no widget");
+    aWidgetChain->AppendElement(widget.get());
+    // In the case when a menulist inside a panel is open, clicking in the
+    // panel should still roll up the menu, so if a different type is found,
+    // stop scanning.
+    nsMenuChainItem* parent = item->GetParent();
+    if (!sameTypeCount) {
+      count++;
+      if (!parent || item->Frame()->PopupType() != parent->Frame()->PopupType() ||
+                     item->IsContextMenu() != parent->IsContextMenu()) {
+        sameTypeCount = count;
+      }
+    }
+    item = parent;
+  }
+
+  return sameTypeCount;
+}
+
+nsIWidget*
+nsXULPopupManager::GetRollupWidget()
+{
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  return item ? item->Frame()->GetWidget() : nullptr;
+}
+
+void
+nsXULPopupManager::AdjustPopupsOnWindowChange(nsPIDOMWindowOuter* aWindow)
+{
+  // When the parent window is moved, adjust any child popups. Dismissable
+  // menus and panels are expected to roll up when a window is moved, so there
+  // is no need to check these popups, only the noautohide popups.
+
+  // The items are added to a list so that they can be adjusted bottom to top.
+  nsTArray<nsMenuPopupFrame *> list;
+
+  nsMenuChainItem* item = mNoHidePanels;
+  while (item) {
+    // only move popups that are within the same window and where auto
+    // positioning has not been disabled
+    nsMenuPopupFrame* frame = item->Frame();
+    if (frame->GetAutoPosition()) {
+      nsIContent* popup = frame->GetContent();
+      if (popup) {
+        nsIDocument* document = popup->GetUncomposedDoc();
+        if (document) {
+          if (nsPIDOMWindowOuter* window = document->GetWindow()) {
+            window = window->GetPrivateRoot();
+            if (window == aWindow) {
+              list.AppendElement(frame);
+            }
+          }
+        }
+      }
+    }
+
+    item = item->GetParent();
+  }
+
+  for (int32_t l = list.Length() - 1; l >= 0; l--) {
+    list[l]->SetPopupPosition(nullptr, true, false, true);
+  }
+}
+
+void nsXULPopupManager::AdjustPopupsOnWindowChange(nsIPresShell* aPresShell)
+{
+  if (aPresShell->GetDocument()) {
+    AdjustPopupsOnWindowChange(aPresShell->GetDocument()->GetWindow());
+  }
+}
+
+static
+nsMenuPopupFrame* GetPopupToMoveOrResize(nsIFrame* aFrame)
+{
+  nsMenuPopupFrame* menuPopupFrame = do_QueryFrame(aFrame);
+  if (!menuPopupFrame)
+    return nullptr;
+
+  // no point moving or resizing hidden popups
+  if (!menuPopupFrame->IsVisible())
+    return nullptr;
+
+  nsIWidget* widget = menuPopupFrame->GetWidget();
+  if (widget && !widget->IsVisible())
+    return nullptr;
+
+  return menuPopupFrame;
+}
+
+void
+nsXULPopupManager::PopupMoved(nsIFrame* aFrame, nsIntPoint aPnt)
+{
+  nsMenuPopupFrame* menuPopupFrame = GetPopupToMoveOrResize(aFrame);
+  if (!menuPopupFrame)
+    return;
+
+  nsView* view = menuPopupFrame->GetView();
+  if (!view)
+    return;
+
+  // Don't do anything if the popup is already at the specified location. This
+  // prevents recursive calls when a popup is positioned.
+  LayoutDeviceIntRect curDevSize = view->CalcWidgetBounds(eWindowType_popup);
+  nsIWidget* widget = menuPopupFrame->GetWidget();
+  if (curDevSize.x == aPnt.x && curDevSize.y == aPnt.y &&
+      (!widget || widget->GetClientOffset() ==
+                  menuPopupFrame->GetLastClientOffset())) {
+    return;
+  }
+
+  // Update the popup's position using SetPopupPosition if the popup is
+  // anchored and at the parent level as these maintain their position
+  // relative to the parent window. Otherwise, just update the popup to
+  // the specified screen coordinates.
+  if (menuPopupFrame->IsAnchored() &&
+      menuPopupFrame->PopupLevel() == ePopupLevelParent) {
+    menuPopupFrame->SetPopupPosition(nullptr, true, false, true);
+  }
+  else {
+    CSSPoint cssPos = LayoutDeviceIntPoint::FromUnknownPoint(aPnt)
+                    / menuPopupFrame->PresContext()->CSSToDevPixelScale();
+    menuPopupFrame->MoveTo(RoundedToInt(cssPos), false);
+  }
+}
+
+void
+nsXULPopupManager::PopupResized(nsIFrame* aFrame, LayoutDeviceIntSize aSize)
+{
+  nsMenuPopupFrame* menuPopupFrame = GetPopupToMoveOrResize(aFrame);
+  if (!menuPopupFrame)
+    return;
+
+  nsView* view = menuPopupFrame->GetView();
+  if (!view)
+    return;
+
+  LayoutDeviceIntRect curDevSize = view->CalcWidgetBounds(eWindowType_popup);
+  // If the size is what we think it is, we have nothing to do.
+  if (curDevSize.width == aSize.width && curDevSize.height == aSize.height)
+    return;
+
+  nsIContent* popup = menuPopupFrame->GetContent();
+
+  // Only set the width and height if the popup already has these attributes.
+  if (!popup->HasAttr(kNameSpaceID_None, nsGkAtoms::width) ||
+      !popup->HasAttr(kNameSpaceID_None, nsGkAtoms::height)) {
+    return;
+  }
+
+  // The size is different. Convert the actual size to css pixels and store it
+  // as 'width' and 'height' attributes on the popup.
+  nsPresContext* presContext = menuPopupFrame->PresContext();
+
+  CSSIntSize newCSS(presContext->DevPixelsToIntCSSPixels(aSize.width),
+                    presContext->DevPixelsToIntCSSPixels(aSize.height));
+
+  nsAutoString width, height;
+  width.AppendInt(newCSS.width);
+  height.AppendInt(newCSS.height);
+  popup->SetAttr(kNameSpaceID_None, nsGkAtoms::width, width, false);
+  popup->SetAttr(kNameSpaceID_None, nsGkAtoms::height, height, true);
+}
+
+nsMenuPopupFrame*
+nsXULPopupManager::GetPopupFrameForContent(nsIContent* aContent, bool aShouldFlush)
+{
+  if (aShouldFlush) {
+    nsIDocument *document = aContent->GetUncomposedDoc();
+    if (document) {
+      nsCOMPtr<nsIPresShell> presShell = document->GetShell();
+      if (presShell)
+        presShell->FlushPendingNotifications(Flush_Layout);
+    }
+  }
+
+  return do_QueryFrame(aContent->GetPrimaryFrame());
+}
+
+nsMenuChainItem*
+nsXULPopupManager::GetTopVisibleMenu()
+{
+  nsMenuChainItem* item = mPopups;
+  while (item && item->Frame()->PopupState() == ePopupInvisible)
+    item = item->GetParent();
+  return item;
+}
+
+void
+nsXULPopupManager::GetMouseLocation(nsIDOMNode** aNode, int32_t* aOffset)
+{
+  *aNode = mRangeParent;
+  NS_IF_ADDREF(*aNode);
+  *aOffset = mRangeOffset;
+}
+
+void
+nsXULPopupManager::InitTriggerEvent(nsIDOMEvent* aEvent, nsIContent* aPopup,
+                                    nsIContent** aTriggerContent)
+{
+  mCachedMousePoint = LayoutDeviceIntPoint(0, 0);
+
+  if (aTriggerContent) {
+    *aTriggerContent = nullptr;
+    if (aEvent) {
+      // get the trigger content from the event
+      nsCOMPtr<nsIContent> target = do_QueryInterface(
+        aEvent->InternalDOMEvent()->GetTarget());
+      target.forget(aTriggerContent);
+    }
+  }
+
+  mCachedModifiers = 0;
+
+  nsCOMPtr<nsIDOMUIEvent> uiEvent = do_QueryInterface(aEvent);
+  if (uiEvent) {
+    uiEvent->GetRangeParent(getter_AddRefs(mRangeParent));
+    uiEvent->GetRangeOffset(&mRangeOffset);
+
+    // get the event coordinates relative to the root frame of the document
+    // containing the popup.
+    NS_ASSERTION(aPopup, "Expected a popup node");
+    WidgetEvent* event = aEvent->WidgetEventPtr();
+    if (event) {
+      WidgetInputEvent* inputEvent = event->AsInputEvent();
+      if (inputEvent) {
+        mCachedModifiers = inputEvent->mModifiers;
+      }
+      nsIDocument* doc = aPopup->GetUncomposedDoc();
+      if (doc) {
+        nsIPresShell* presShell = doc->GetShell();
+        nsPresContext* presContext;
+        if (presShell && (presContext = presShell->GetPresContext())) {
+          nsPresContext* rootDocPresContext =
+            presContext->GetRootPresContext();
+          if (!rootDocPresContext)
+            return;
+          nsIFrame* rootDocumentRootFrame = rootDocPresContext->
+              PresShell()->FrameManager()->GetRootFrame();
+          if ((event->mClass == eMouseEventClass || 
+               event->mClass == eMouseScrollEventClass ||
+               event->mClass == eWheelEventClass) &&
+               !event->AsGUIEvent()->mWidget) {
+            // no widget, so just use the client point if available
+            nsCOMPtr<nsIDOMMouseEvent> mouseEvent = do_QueryInterface(aEvent);
+            nsIntPoint clientPt;
+            mouseEvent->GetClientX(&clientPt.x);
+            mouseEvent->GetClientY(&clientPt.y);
+
+            // XXX this doesn't handle IFRAMEs in transforms
+            nsPoint thisDocToRootDocOffset = presShell->FrameManager()->
+              GetRootFrame()->GetOffsetToCrossDoc(rootDocumentRootFrame);
+            // convert to device pixels
+            mCachedMousePoint.x = presContext->AppUnitsToDevPixels(
+                nsPresContext::CSSPixelsToAppUnits(clientPt.x) + thisDocToRootDocOffset.x);
+            mCachedMousePoint.y = presContext->AppUnitsToDevPixels(
+                nsPresContext::CSSPixelsToAppUnits(clientPt.y) + thisDocToRootDocOffset.y);
+          }
+          else if (rootDocumentRootFrame) {
+            nsPoint pnt =
+              nsLayoutUtils::GetEventCoordinatesRelativeTo(event, rootDocumentRootFrame);
+            mCachedMousePoint = LayoutDeviceIntPoint(rootDocPresContext->AppUnitsToDevPixels(pnt.x),
+                                                     rootDocPresContext->AppUnitsToDevPixels(pnt.y));
+          }
+        }
+      }
+    }
+  }
+  else {
+    mRangeParent = nullptr;
+    mRangeOffset = 0;
+  }
+}
+
+void
+nsXULPopupManager::SetActiveMenuBar(nsMenuBarFrame* aMenuBar, bool aActivate)
+{
+  if (aActivate)
+    mActiveMenuBar = aMenuBar;
+  else if (mActiveMenuBar == aMenuBar)
+    mActiveMenuBar = nullptr;
+
+  UpdateKeyboardListeners();
+}
+
+void
+nsXULPopupManager::ShowMenu(nsIContent *aMenu,
+                            bool aSelectFirstItem,
+                            bool aAsynchronous)
+{
+  // generate any template content first. Otherwise, the menupopup may not
+  // have been created yet.
+  if (aMenu) {
+    nsIContent* element = aMenu;
+    do {
+      nsCOMPtr<nsIDOMXULElement> xulelem = do_QueryInterface(element);
+      if (xulelem) {
+        nsCOMPtr<nsIXULTemplateBuilder> builder;
+        xulelem->GetBuilder(getter_AddRefs(builder));
+        if (builder) {
+          builder->CreateContents(aMenu, true);
+          break;
+        }
+      }
+      element = element->GetParent();
+    } while (element);
+  }
+
+  nsMenuFrame* menuFrame = do_QueryFrame(aMenu->GetPrimaryFrame());
+  if (!menuFrame || !menuFrame->IsMenu())
+    return;
+
+  nsMenuPopupFrame* popupFrame =  menuFrame->GetPopup();
+  if (!popupFrame || !MayShowPopup(popupFrame))
+    return;
+
+  // inherit whether or not we're a context menu from the parent
+  bool parentIsContextMenu = false;
+  bool onMenuBar = false;
+  bool onmenu = menuFrame->IsOnMenu();
+
+  nsMenuParent* parent = menuFrame->GetMenuParent();
+  if (parent && onmenu) {
+    parentIsContextMenu = parent->IsContextMenu();
+    onMenuBar = parent->IsMenuBar();
+  }
+
+  nsAutoString position;
+
+#ifdef XP_MACOSX
+  nsCOMPtr<nsIDOMXULMenuListElement> menulist = do_QueryInterface(aMenu);
+  bool isNonEditableMenulist = false;
+  if (menulist) {
+    bool editable;
+    menulist->GetEditable(&editable);
+    isNonEditableMenulist = !editable;
+  }
+
+  if (isNonEditableMenulist) {
+    position.AssignLiteral("selection");
+  }
+  else
+#endif
+
+  if (onMenuBar || !onmenu)
+    position.AssignLiteral("after_start");
+  else
+    position.AssignLiteral("end_before");
+
+  // there is no trigger event for menus
+  InitTriggerEvent(nullptr, nullptr, nullptr);
+  popupFrame->InitializePopup(menuFrame->GetAnchor(), nullptr, position, 0, 0,
+                              MenuPopupAnchorType_Node, true);
+
+  if (aAsynchronous) {
+    nsCOMPtr<nsIRunnable> event =
+      new nsXULPopupShowingEvent(popupFrame->GetContent(),
+                                 parentIsContextMenu, aSelectFirstItem);
+    NS_DispatchToCurrentThread(event);
+  }
+  else {
+    nsCOMPtr<nsIContent> popupContent = popupFrame->GetContent();
+    FirePopupShowingEvent(popupContent, parentIsContextMenu, aSelectFirstItem);
+  }
+}
+
+void
+nsXULPopupManager::ShowPopup(nsIContent* aPopup,
+                             nsIContent* aAnchorContent,
+                             const nsAString& aPosition,
+                             int32_t aXPos, int32_t aYPos,
+                             bool aIsContextMenu,
+                             bool aAttributesOverride,
+                             bool aSelectFirstItem,
+                             nsIDOMEvent* aTriggerEvent)
+{
+  nsMenuPopupFrame* popupFrame = GetPopupFrameForContent(aPopup, true);
+  if (!popupFrame || !MayShowPopup(popupFrame))
+    return;
+
+  nsCOMPtr<nsIContent> triggerContent;
+  InitTriggerEvent(aTriggerEvent, aPopup, getter_AddRefs(triggerContent));
+
+  popupFrame->InitializePopup(aAnchorContent, triggerContent, aPosition,
+                              aXPos, aYPos, MenuPopupAnchorType_Node, aAttributesOverride);
+
+  FirePopupShowingEvent(aPopup, aIsContextMenu, aSelectFirstItem);
+}
+
+void
+nsXULPopupManager::ShowPopupAtScreen(nsIContent* aPopup,
+                                     int32_t aXPos, int32_t aYPos,
+                                     bool aIsContextMenu,
+                                     nsIDOMEvent* aTriggerEvent)
+{
+  nsMenuPopupFrame* popupFrame = GetPopupFrameForContent(aPopup, true);
+  if (!popupFrame || !MayShowPopup(popupFrame))
+    return;
+
+  nsCOMPtr<nsIContent> triggerContent;
+  InitTriggerEvent(aTriggerEvent, aPopup, getter_AddRefs(triggerContent));
+
+  popupFrame->InitializePopupAtScreen(triggerContent, aXPos, aYPos, aIsContextMenu);
+  FirePopupShowingEvent(aPopup, aIsContextMenu, false);
+}
+
+void
+nsXULPopupManager::ShowPopupAtScreenRect(nsIContent* aPopup,
+                                         const nsAString& aPosition,
+                                         const nsIntRect& aRect,
+                                         bool aIsContextMenu,
+                                         bool aAttributesOverride,
+                                         nsIDOMEvent* aTriggerEvent)
+{
+  nsMenuPopupFrame* popupFrame = GetPopupFrameForContent(aPopup, true);
+  if (!popupFrame || !MayShowPopup(popupFrame))
+    return;
+
+  nsCOMPtr<nsIContent> triggerContent;
+  InitTriggerEvent(aTriggerEvent, aPopup, getter_AddRefs(triggerContent));
+
+  popupFrame->InitializePopupAtRect(triggerContent, aPosition,
+                                    aRect, aAttributesOverride);
+
+  FirePopupShowingEvent(aPopup, aIsContextMenu, false);
+}
+
+void
+nsXULPopupManager::ShowTooltipAtScreen(nsIContent* aPopup,
+                                       nsIContent* aTriggerContent,
+                                       int32_t aXPos, int32_t aYPos)
+{
+  nsMenuPopupFrame* popupFrame = GetPopupFrameForContent(aPopup, true);
+  if (!popupFrame || !MayShowPopup(popupFrame))
+    return;
+
+  InitTriggerEvent(nullptr, nullptr, nullptr);
+
+  nsPresContext* pc = popupFrame->PresContext();
+  mCachedMousePoint = LayoutDeviceIntPoint(pc->CSSPixelsToDevPixels(aXPos),
+                                           pc->CSSPixelsToDevPixels(aYPos));
+
+  // coordinates are relative to the root widget
+  nsPresContext* rootPresContext = pc->GetRootPresContext();
+  if (rootPresContext) {
+    nsIWidget *rootWidget = rootPresContext->GetRootWidget();
+    if (rootWidget) {
+      mCachedMousePoint -= rootWidget->WidgetToScreenOffset();
+    }
+  }
+
+  popupFrame->InitializePopupAtScreen(aTriggerContent, aXPos, aYPos, false);
+
+  FirePopupShowingEvent(aPopup, false, false);
+}
+
+void
+nsXULPopupManager::ShowPopupWithAnchorAlign(nsIContent* aPopup,
+                                            nsIContent* aAnchorContent,
+                                            nsAString& aAnchor,
+                                            nsAString& aAlign,
+                                            int32_t aXPos, int32_t aYPos,
+                                            bool aIsContextMenu)
+{
+  nsMenuPopupFrame* popupFrame = GetPopupFrameForContent(aPopup, true);
+  if (!popupFrame || !MayShowPopup(popupFrame))
+    return;
+
+  InitTriggerEvent(nullptr, nullptr, nullptr);
+
+  popupFrame->InitializePopupWithAnchorAlign(aAnchorContent, aAnchor,
+                                             aAlign, aXPos, aYPos);
+  FirePopupShowingEvent(aPopup, aIsContextMenu, false);
+}
+
+static void
+CheckCaretDrawingState()
+{
+  // There is 1 caret per document, we need to find the focused
+  // document and erase its caret.
+  nsIFocusManager* fm = nsFocusManager::GetFocusManager();
+  if (fm) {
+    nsCOMPtr<mozIDOMWindowProxy> window;
+    fm->GetFocusedWindow(getter_AddRefs(window));
+    if (!window)
+      return;
+
+    auto* piWindow = nsPIDOMWindowOuter::From(window);
+    MOZ_ASSERT(piWindow);
+
+    nsCOMPtr<nsIDocument> focusedDoc = piWindow->GetDoc();
+    if (!focusedDoc)
+      return;
+
+    nsIPresShell* presShell = focusedDoc->GetShell();
+    if (!presShell)
+      return;
+
+    RefPtr<nsCaret> caret = presShell->GetCaret();
+    if (!caret)
+      return;
+    caret->SchedulePaint();
+  }
+}
+
+void
+nsXULPopupManager::ShowPopupCallback(nsIContent* aPopup,
+                                     nsMenuPopupFrame* aPopupFrame,
+                                     bool aIsContextMenu,
+                                     bool aSelectFirstItem)
+{
+  nsPopupType popupType = aPopupFrame->PopupType();
+  bool ismenu = (popupType == ePopupTypeMenu);
+
+  nsMenuChainItem* item =
+    new nsMenuChainItem(aPopupFrame, aIsContextMenu, popupType);
+  if (!item)
+    return;
+
+  // install keyboard event listeners for navigating menus. For panels, the
+  // escape key may be used to close the panel. However, the ignorekeys
+  // attribute may be used to disable adding these event listeners for popups
+  // that want to handle their own keyboard events.
+  nsAutoString ignorekeys;
+  aPopup->GetAttr(kNameSpaceID_None, nsGkAtoms::ignorekeys, ignorekeys);
+  if (ignorekeys.EqualsLiteral("true")) {
+    item->SetIgnoreKeys(eIgnoreKeys_True);
+  } else if (ignorekeys.EqualsLiteral("shortcuts")) {
+    item->SetIgnoreKeys(eIgnoreKeys_Shortcuts);
+  }
+
+  if (ismenu) {
+    // if the menu is on a menubar, use the menubar's listener instead
+    nsMenuFrame* menuFrame = do_QueryFrame(aPopupFrame->GetParent());
+    if (menuFrame) {
+      item->SetOnMenuBar(menuFrame->IsOnMenuBar());
+    }
+  }
+
+  // use a weak frame as the popup will set an open attribute if it is a menu
+  nsWeakFrame weakFrame(aPopupFrame);
+  aPopupFrame->ShowPopup(aIsContextMenu);
+  ENSURE_TRUE(weakFrame.IsAlive());
+
+  // popups normally hide when an outside click occurs. Panels may use
+  // the noautohide attribute to disable this behaviour. It is expected
+  // that the application will hide these popups manually. The tooltip
+  // listener will handle closing the tooltip also.
+  if (aPopupFrame->IsNoAutoHide() || popupType == ePopupTypeTooltip) {
+    item->SetParent(mNoHidePanels);
+    mNoHidePanels = item;
+  }
+  else {
+    nsIContent* oldmenu = nullptr;
+    if (mPopups)
+      oldmenu = mPopups->Content();
+    item->SetParent(mPopups);
+    mPopups = item;
+    SetCaptureState(oldmenu);
+  }
+
+  if (aSelectFirstItem) {
+    nsMenuFrame* next = GetNextMenuItem(aPopupFrame, nullptr, true);
+    aPopupFrame->SetCurrentMenuItem(next);
+  }
+
+  if (ismenu)
+    UpdateMenuItems(aPopup);
+
+  // Caret visibility may have been affected, ensure that
+  // the caret isn't now drawn when it shouldn't be.
+  CheckCaretDrawingState();
+}
+
+void
+nsXULPopupManager::HidePopup(nsIContent* aPopup,
+                             bool aHideChain,
+                             bool aDeselectMenu,
+                             bool aAsynchronous,
+                             bool aIsCancel,
+                             nsIContent* aLastPopup)
+{
+  // if the popup is on the nohide panels list, remove it but don't close any
+  // other panels
+  nsMenuPopupFrame* popupFrame = nullptr;
+  bool foundPanel = false;
+  nsMenuChainItem* item = mNoHidePanels;
+  while (item) {
+    if (item->Content() == aPopup) {
+      foundPanel = true;
+      popupFrame = item->Frame();
+      break;
+    }
+    item = item->GetParent();
+  }
+
+  // when removing a menu, all of the child popups must be closed
+  nsMenuChainItem* foundMenu = nullptr;
+  item = mPopups;
+  while (item) {
+    if (item->Content() == aPopup) {
+      foundMenu = item;
+      break;
+    }
+    item = item->GetParent();
+  }
+
+  nsPopupType type = ePopupTypePanel;
+  bool deselectMenu = false;
+  nsCOMPtr<nsIContent> popupToHide, nextPopup, lastPopup;
+  if (foundMenu) {
+    // at this point, foundMenu will be set to the found item in the list. If
+    // foundMenu is the topmost menu, the one to remove, then there are no other
+    // popups to hide. If foundMenu is not the topmost menu, then there may be
+    // open submenus below it. In this case, we need to make sure that those
+    // submenus are closed up first. To do this, we scan up the menu list to
+    // find the topmost popup with only menus between it and foundMenu and
+    // close that menu first. In synchronous mode, the FirePopupHidingEvent
+    // method will be called which in turn calls HidePopupCallback to close up
+    // the next popup in the chain. These two methods will be called in
+    // sequence recursively to close up all the necessary popups. In
+    // asynchronous mode, a similar process occurs except that the
+    // FirePopupHidingEvent method is called asynchronously. In either case,
+    // nextPopup is set to the content node of the next popup to close, and
+    // lastPopup is set to the last popup in the chain to close, which will be
+    // aPopup, or null to close up all menus.
+
+    nsMenuChainItem* topMenu = foundMenu;
+    // Use IsMenu to ensure that foundMenu is a menu and scan down the child
+    // list until a non-menu is found. If foundMenu isn't a menu at all, don't
+    // scan and just close up this menu.
+    if (foundMenu->IsMenu()) {
+      item = topMenu->GetChild();
+      while (item && item->IsMenu()) {
+        topMenu = item;
+        item = item->GetChild();
+      }
+    }
+    
+    deselectMenu = aDeselectMenu;
+    popupToHide = topMenu->Content();
+    popupFrame = topMenu->Frame();
+    type = popupFrame->PopupType();
+
+    nsMenuChainItem* parent = topMenu->GetParent();
+
+    // close up another popup if there is one, and we are either hiding the
+    // entire chain or the item to hide isn't the topmost popup.
+    if (parent && (aHideChain || topMenu != foundMenu))
+      nextPopup = parent->Content();
+
+    lastPopup = aLastPopup ? aLastPopup : (aHideChain ? nullptr : aPopup);
+  }
+  else if (foundPanel) {
+    popupToHide = aPopup;
+  } else {
+    // When the popup is in the popuppositioning state, it will not be in the
+    // mPopups list. We need another way to find it and make sure it does not
+    // continue the popup showing process.
+    popupFrame = do_QueryFrame(aPopup->GetPrimaryFrame());
+    if (popupFrame) {
+      if (popupFrame->PopupState() == ePopupPositioning) {
+        // Do basically the same thing we would have done if we had found the
+        // popup in the mPopups list.
+        deselectMenu = aDeselectMenu;
+        popupToHide = aPopup;
+        type = popupFrame->PopupType();
+      } else {
+        // The popup is not positioning. If we were supposed to have handled
+        // closing it, it should have been in mPopups or mNoHidePanels
+        popupFrame = nullptr;
+      }
+    }
+  }
+
+  if (popupFrame) {
+    nsPopupState state = popupFrame->PopupState();
+    // if the popup is already being hidden, don't attempt to hide it again
+    if (state == ePopupHiding)
+      return;
+    // change the popup state to hiding. Don't set the hiding state if the
+    // popup is invisible, otherwise nsMenuPopupFrame::HidePopup will
+    // run again. In the invisible state, we just want the events to fire.
+    if (state != ePopupInvisible)
+      popupFrame->SetPopupState(ePopupHiding);
+
+    // for menus, popupToHide is always the frontmost item in the list to hide.
+    if (aAsynchronous) {
+      nsCOMPtr<nsIRunnable> event =
+        new nsXULPopupHidingEvent(popupToHide, nextPopup, lastPopup,
+                                  type, deselectMenu, aIsCancel);
+        NS_DispatchToCurrentThread(event);
+    }
+    else {
+      FirePopupHidingEvent(popupToHide, nextPopup, lastPopup,
+                           popupFrame->PresContext(), type, deselectMenu, aIsCancel);
+    }
+  }
+}
+
+// This is used to hide the popup after a transition finishes.
+class TransitionEnder : public nsIDOMEventListener
+{
+protected:
+  virtual ~TransitionEnder() { }
+
+public:
+
+  nsCOMPtr<nsIContent> mContent;
+  bool mDeselectMenu;
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS(TransitionEnder)
+
+  TransitionEnder(nsIContent* aContent, bool aDeselectMenu)
+    : mContent(aContent), mDeselectMenu(aDeselectMenu)
+  {
+  }
+
+  NS_IMETHOD HandleEvent(nsIDOMEvent* aEvent) override
+  {
+    mContent->RemoveSystemEventListener(NS_LITERAL_STRING("transitionend"), this, false);
+
+    nsMenuPopupFrame* popupFrame = do_QueryFrame(mContent->GetPrimaryFrame());
+
+    // Now hide the popup. There could be other properties transitioning, but
+    // we'll assume they all end at the same time and just hide the popup upon
+    // the first one ending.
+    nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+    if (pm && popupFrame) {
+      pm->HidePopupCallback(mContent, popupFrame, nullptr, nullptr,
+                            popupFrame->PopupType(), mDeselectMenu);
+    }
+
+    return NS_OK;
+  }
+};
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TransitionEnder)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TransitionEnder)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TransitionEnder)
+  NS_INTERFACE_MAP_ENTRY(nsIDOMEventListener)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTION(TransitionEnder, mContent);
+
+void
+nsXULPopupManager::HidePopupCallback(nsIContent* aPopup,
+                                     nsMenuPopupFrame* aPopupFrame,
+                                     nsIContent* aNextPopup,
+                                     nsIContent* aLastPopup,
+                                     nsPopupType aPopupType,
+                                     bool aDeselectMenu)
+{
+  if (mCloseTimer && mTimerMenu == aPopupFrame) {
+    mCloseTimer->Cancel();
+    mCloseTimer = nullptr;
+    mTimerMenu = nullptr;
+  }
+
+  // The popup to hide is aPopup. Search the list again to find the item that
+  // corresponds to the popup to hide aPopup. This is done because it's
+  // possible someone added another item (attempted to open another popup)
+  // or removed a popup frame during the event processing so the item isn't at
+  // the front anymore.
+  nsMenuChainItem* item = mNoHidePanels;
+  while (item) {
+    if (item->Content() == aPopup) {
+      item->Detach(&mNoHidePanels);
+      break;
+    }
+    item = item->GetParent();
+  }
+
+  if (!item) {
+    item = mPopups;
+    while (item) {
+      if (item->Content() == aPopup) {
+        item->Detach(&mPopups);
+        SetCaptureState(aPopup);
+        break;
+      }
+      item = item->GetParent();
+    }
+  }
+
+  delete item;
+
+  nsWeakFrame weakFrame(aPopupFrame);
+  aPopupFrame->HidePopup(aDeselectMenu, ePopupClosed);
+  ENSURE_TRUE(weakFrame.IsAlive());
+
+  // send the popuphidden event synchronously. This event has no default
+  // behaviour.
+  nsEventStatus status = nsEventStatus_eIgnore;
+  WidgetMouseEvent event(true, eXULPopupHidden, nullptr,
+                         WidgetMouseEvent::eReal);
+  EventDispatcher::Dispatch(aPopup, aPopupFrame->PresContext(),
+                            &event, nullptr, &status);
+  ENSURE_TRUE(weakFrame.IsAlive());
+
+  // if there are more popups to close, look for the next one
+  if (aNextPopup && aPopup != aLastPopup) {
+    nsMenuChainItem* foundMenu = nullptr;
+    nsMenuChainItem* item = mPopups;
+    while (item) {
+      if (item->Content() == aNextPopup) {
+        foundMenu = item;
+        break;
+      }
+      item = item->GetParent();
+    }
+
+    // continue hiding the chain of popups until the last popup aLastPopup
+    // is reached, or until a popup of a different type is reached. This
+    // last check is needed so that a menulist inside a non-menu panel only
+    // closes the menu and not the panel as well.
+    if (foundMenu &&
+        (aLastPopup || aPopupType == foundMenu->PopupType())) {
+
+      nsCOMPtr<nsIContent> popupToHide = item->Content();
+      nsMenuChainItem* parent = item->GetParent();
+
+      nsCOMPtr<nsIContent> nextPopup;
+      if (parent && popupToHide != aLastPopup)
+        nextPopup = parent->Content();
+
+      nsMenuPopupFrame* popupFrame = item->Frame();
+      nsPopupState state = popupFrame->PopupState();
+      if (state == ePopupHiding)
+        return;
+      if (state != ePopupInvisible)
+        popupFrame->SetPopupState(ePopupHiding);
+
+      FirePopupHidingEvent(popupToHide, nextPopup, aLastPopup,
+                           popupFrame->PresContext(),
+                           foundMenu->PopupType(), aDeselectMenu, false);
+    }
+  }
+}
+
+void
+nsXULPopupManager::HidePopup(nsIFrame* aFrame)
+{
+  nsMenuPopupFrame* popup = do_QueryFrame(aFrame);
+  if (popup)
+    HidePopup(aFrame->GetContent(), false, true, false, false);
+}
+
+void
+nsXULPopupManager::HidePopupAfterDelay(nsMenuPopupFrame* aPopup)
+{
+  // Don't close up immediately.
+  // Kick off a close timer.
+  KillMenuTimer();
+
+  int32_t menuDelay =
+    LookAndFeel::GetInt(LookAndFeel::eIntID_SubmenuDelay, 300); // ms
+
+  // Kick off the timer.
+  mCloseTimer = do_CreateInstance("@mozilla.org/timer;1");
+  mCloseTimer->InitWithCallback(this, menuDelay, nsITimer::TYPE_ONE_SHOT);
+
+  // the popup will call PopupDestroyed if it is destroyed, which checks if it
+  // is set to mTimerMenu, so it should be safe to keep a reference to it
+  mTimerMenu = aPopup;
+}
+
+void
+nsXULPopupManager::HidePopupsInList(const nsTArray<nsMenuPopupFrame *> &aFrames)
+{
+  // Create a weak frame list. This is done in a separate array with the
+  // right capacity predetermined, otherwise the array would get resized and
+  // move the weak frame pointers around.
+  nsTArray<nsWeakFrame> weakPopups(aFrames.Length());
+  uint32_t f;
+  for (f = 0; f < aFrames.Length(); f++) {
+    nsWeakFrame* wframe = weakPopups.AppendElement();
+    if (wframe)
+      *wframe = aFrames[f];
+  }
+
+  for (f = 0; f < weakPopups.Length(); f++) {
+    // check to ensure that the frame is still alive before hiding it.
+    if (weakPopups[f].IsAlive()) {
+      nsMenuPopupFrame* frame =
+        static_cast<nsMenuPopupFrame *>(weakPopups[f].GetFrame());
+      frame->HidePopup(true, ePopupInvisible);
+    }
+  }
+
+  SetCaptureState(nullptr);
+}
+
+void
+nsXULPopupManager::EnableRollup(nsIContent* aPopup, bool aShouldRollup)
+{
+#ifndef MOZ_GTK
+  if (aShouldRollup) {
+    nsMenuChainItem* item = mNoHidePanels;
+    while (item) {
+      if (item->Content() == aPopup) {
+        item->Detach(&mNoHidePanels);
+        nsIContent* oldmenu = nullptr;
+        if (mPopups)
+          oldmenu = mPopups->Content();
+        item->SetParent(mPopups);
+        mPopups = item;
+        SetCaptureState(oldmenu);
+        return;
+      }
+      item = item->GetParent();
+    }
+  } else {
+    nsMenuChainItem* item = mPopups;
+    while (item) {
+      if (item->Content() == aPopup) {
+        item->Detach(&mPopups);
+        item->SetParent(mNoHidePanels);
+        mNoHidePanels = item;
+        SetCaptureState(nullptr);
+        return;
+      }
+      item = item->GetParent();
+    }
+  }
+#endif
+}
+
+bool
+nsXULPopupManager::IsChildOfDocShell(nsIDocument* aDoc, nsIDocShellTreeItem* aExpected)
+{
+  nsCOMPtr<nsIDocShellTreeItem> docShellItem(aDoc->GetDocShell());
+  while(docShellItem) {
+    if (docShellItem == aExpected)
+      return true;
+
+    nsCOMPtr<nsIDocShellTreeItem> parent;
+    docShellItem->GetParent(getter_AddRefs(parent));
+    docShellItem = parent;
+  }
+
+  return false;
+}
+
+void
+nsXULPopupManager::HidePopupsInDocShell(nsIDocShellTreeItem* aDocShellToHide)
+{
+  nsTArray<nsMenuPopupFrame *> popupsToHide;
+
+  // iterate to get the set of popup frames to hide
+  nsMenuChainItem* item = mPopups;
+  while (item) {
+    nsMenuChainItem* parent = item->GetParent();
+    if (item->Frame()->PopupState() != ePopupInvisible &&
+        IsChildOfDocShell(item->Content()->OwnerDoc(), aDocShellToHide)) {
+      nsMenuPopupFrame* frame = item->Frame();
+      item->Detach(&mPopups);
+      delete item;
+      popupsToHide.AppendElement(frame);
+    }
+    item = parent;
+  }
+
+  // now look for panels to hide
+  item = mNoHidePanels;
+  while (item) {
+    nsMenuChainItem* parent = item->GetParent();
+    if (item->Frame()->PopupState() != ePopupInvisible &&
+        IsChildOfDocShell(item->Content()->OwnerDoc(), aDocShellToHide)) {
+      nsMenuPopupFrame* frame = item->Frame();
+      item->Detach(&mNoHidePanels);
+      delete item;
+      popupsToHide.AppendElement(frame);
+    }
+    item = parent;
+  }
+
+  HidePopupsInList(popupsToHide);
+}
+
+void
+nsXULPopupManager::ExecuteMenu(nsIContent* aMenu, nsXULMenuCommandEvent* aEvent)
+{
+  CloseMenuMode cmm = CloseMenuMode_Auto;
+
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::none, &nsGkAtoms::single, nullptr};
+
+  switch (aMenu->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::closemenu,
+                                 strings, eCaseMatters)) {
+    case 0:
+      cmm = CloseMenuMode_None;
+      break;
+    case 1:
+      cmm = CloseMenuMode_Single;
+      break;
+    default:
+      break;
+  }
+
+  // When a menuitem is selected to be executed, first hide all the open
+  // popups, but don't remove them yet. This is needed when a menu command
+  // opens a modal dialog. The views associated with the popups needed to be
+  // hidden and the accesibility events fired before the command executes, but
+  // the popuphiding/popuphidden events are fired afterwards.
+  nsTArray<nsMenuPopupFrame *> popupsToHide;
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  if (cmm != CloseMenuMode_None) {
+    while (item) {
+      // if it isn't a <menupopup>, don't close it automatically
+      if (!item->IsMenu())
+        break;
+      nsMenuChainItem* next = item->GetParent();
+      popupsToHide.AppendElement(item->Frame());
+      if (cmm == CloseMenuMode_Single) // only close one level of menu
+        break;
+      item = next;
+    }
+
+    // Now hide the popups. If the closemenu mode is auto, deselect the menu,
+    // otherwise only one popup is closing, so keep the parent menu selected.
+    HidePopupsInList(popupsToHide);
+  }
+
+  aEvent->SetCloseMenuMode(cmm);
+  nsCOMPtr<nsIRunnable> event = aEvent;
+  NS_DispatchToCurrentThread(event);
+}
+
+void
+nsXULPopupManager::FirePopupShowingEvent(nsIContent* aPopup,
+                                         bool aIsContextMenu,
+                                         bool aSelectFirstItem)
+{
+  nsCOMPtr<nsIContent> popup = aPopup; // keep a strong reference to the popup
+
+  nsMenuPopupFrame* popupFrame = do_QueryFrame(aPopup->GetPrimaryFrame());
+  if (!popupFrame)
+    return;
+
+  nsPresContext *presContext = popupFrame->PresContext();
+  nsCOMPtr<nsIPresShell> presShell = presContext->PresShell();
+  nsPopupType popupType = popupFrame->PopupType();
+
+  // generate the child frames if they have not already been generated
+  if (!popupFrame->HasGeneratedChildren()) {
+    popupFrame->SetGeneratedChildren();
+    presShell->FrameConstructor()->GenerateChildFrames(popupFrame);
+  }
+
+  // get the frame again
+  nsIFrame* frame = aPopup->GetPrimaryFrame();
+  if (!frame)
+    return;
+
+  presShell->FrameNeedsReflow(frame, nsIPresShell::eTreeChange,
+                              NS_FRAME_HAS_DIRTY_CHILDREN);
+
+  // cache the popup so that document.popupNode can retrieve the trigger node
+  // during the popupshowing event. It will be cleared below after the event
+  // has fired.
+  mOpeningPopup = aPopup;
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  WidgetMouseEvent event(true, eXULPopupShowing, nullptr,
+                         WidgetMouseEvent::eReal);
+
+  // coordinates are relative to the root widget
+  nsPresContext* rootPresContext =
+    presShell->GetPresContext()->GetRootPresContext();
+  if (rootPresContext) {
+    rootPresContext->PresShell()->GetViewManager()->
+      GetRootWidget(getter_AddRefs(event.mWidget));
+  }
+  else {
+    event.mWidget = nullptr;
+  }
+
+  event.mRefPoint = mCachedMousePoint;
+  event.mModifiers = mCachedModifiers;
+  EventDispatcher::Dispatch(popup, presContext, &event, nullptr, &status);
+
+  mCachedMousePoint = LayoutDeviceIntPoint(0, 0);
+  mOpeningPopup = nullptr;
+
+  mCachedModifiers = 0;
+
+  // if a panel, blur whatever has focus so that the panel can take the focus.
+  // This is done after the popupshowing event in case that event is cancelled.
+  // Using noautofocus="true" will disable this behaviour, which is needed for
+  // the autocomplete widget as it manages focus itself.
+  if (popupType == ePopupTypePanel &&
+      !popup->AttrValueIs(kNameSpaceID_None, nsGkAtoms::noautofocus,
+                           nsGkAtoms::_true, eCaseMatters)) {
+    nsIFocusManager* fm = nsFocusManager::GetFocusManager();
+    if (fm) {
+      nsIDocument* doc = popup->GetUncomposedDoc();
+
+      // Only remove the focus if the currently focused item is ouside the
+      // popup. It isn't a big deal if the current focus is in a child popup
+      // inside the popup as that shouldn't be visible. This check ensures that
+      // a node inside the popup that is focused during a popupshowing event
+      // remains focused.
+      nsCOMPtr<nsIDOMElement> currentFocusElement;
+      fm->GetFocusedElement(getter_AddRefs(currentFocusElement));
+      nsCOMPtr<nsIContent> currentFocus = do_QueryInterface(currentFocusElement);
+      if (doc && currentFocus &&
+          !nsContentUtils::ContentIsCrossDocDescendantOf(currentFocus, popup)) {
+        fm->ClearFocus(doc->GetWindow());
+      }
+    }
+  }
+
+  // clear these as they are no longer valid
+  mRangeParent = nullptr;
+  mRangeOffset = 0;
+
+  // get the frame again in case it went away
+  popupFrame = do_QueryFrame(aPopup->GetPrimaryFrame());
+  if (popupFrame) {
+    // if the event was cancelled, don't open the popup, reset its state back
+    // to closed and clear its trigger content.
+    if (status == nsEventStatus_eConsumeNoDefault) {
+      popupFrame->SetPopupState(ePopupClosed);
+      popupFrame->ClearTriggerContent();
+    }
+    else {
+      // Now check if we need to fire the popuppositioned event. If not, call
+      // ShowPopupCallback directly.
+
+      // The popuppositioned event only fires on arrow panels for now.
+      if (popup->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                          nsGkAtoms::arrow, eCaseMatters)) {
+        popupFrame->ShowWithPositionedEvent();
+        presShell->FrameNeedsReflow(popupFrame, nsIPresShell::eTreeChange,
+                                    NS_FRAME_HAS_DIRTY_CHILDREN);
+      }
+      else {
+        ShowPopupCallback(popup, popupFrame, aIsContextMenu, aSelectFirstItem);
+      }
+    }
+  }
+}
+
+void
+nsXULPopupManager::FirePopupHidingEvent(nsIContent* aPopup,
+                                        nsIContent* aNextPopup,
+                                        nsIContent* aLastPopup,
+                                        nsPresContext *aPresContext,
+                                        nsPopupType aPopupType,
+                                        bool aDeselectMenu,
+                                        bool aIsCancel)
+{
+  nsCOMPtr<nsIPresShell> presShell = aPresContext->PresShell();
+  mozilla::Unused << presShell; // This presShell may be keeping things alive on non GTK platforms
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  WidgetMouseEvent event(true, eXULPopupHiding, nullptr,
+                         WidgetMouseEvent::eReal);
+  EventDispatcher::Dispatch(aPopup, aPresContext, &event, nullptr, &status);
+
+  // when a panel is closed, blur whatever has focus inside the popup
+  if (aPopupType == ePopupTypePanel &&
+      !aPopup->AttrValueIs(kNameSpaceID_None, nsGkAtoms::noautofocus,
+                           nsGkAtoms::_true, eCaseMatters)) {
+    nsIFocusManager* fm = nsFocusManager::GetFocusManager();
+    if (fm) {
+      nsIDocument* doc = aPopup->GetUncomposedDoc();
+
+      // Remove the focus from the focused node only if it is inside the popup.
+      nsCOMPtr<nsIDOMElement> currentFocusElement;
+      fm->GetFocusedElement(getter_AddRefs(currentFocusElement));
+      nsCOMPtr<nsIContent> currentFocus = do_QueryInterface(currentFocusElement);
+      if (doc && currentFocus &&
+          nsContentUtils::ContentIsCrossDocDescendantOf(currentFocus, aPopup)) {
+        fm->ClearFocus(doc->GetWindow());
+      }
+    }
+  }
+
+  // get frame again in case it went away
+  nsMenuPopupFrame* popupFrame = do_QueryFrame(aPopup->GetPrimaryFrame());
+  if (popupFrame) {
+    // if the event was cancelled, don't hide the popup, and reset its
+    // state back to open. Only popups in chrome shells can prevent a popup
+    // from hiding.
+    if (status == nsEventStatus_eConsumeNoDefault &&
+        !popupFrame->IsInContentShell()) {
+      // XXXndeakin
+      // If an attempt was made to hide this popup before the popupshown event
+      // fired, then ePopupShown is set here even though it should be
+      // ePopupVisible. This probably isn't worth the hassle of handling.
+      popupFrame->SetPopupState(ePopupShown);
+    }
+    else {
+      // If the popup has an animate attribute and it is not set to false, check
+      // if it has a closing transition and wait for it to finish. The transition
+      // may still occur either way, but the view will be hidden and you won't be
+      // able to see it. If there is a next popup, indicating that mutliple popups
+      // are rolling up, don't wait and hide the popup right away since the effect
+      // would likely be undesirable. Transitions are currently disabled on Linux
+      // due to rendering issues on certain configurations.
+#ifndef MOZ_WIDGET_GTK
+      if (!aNextPopup && aPopup->HasAttr(kNameSpaceID_None, nsGkAtoms::animate)) {
+        // If animate="false" then don't transition at all. If animate="cancel",
+        // only show the transition if cancelling the popup or rolling up.
+        // Otherwise, always show the transition.
+        nsAutoString animate;
+        aPopup->GetAttr(kNameSpaceID_None, nsGkAtoms::animate, animate);
+
+        if (!animate.EqualsLiteral("false") &&
+            (!animate.EqualsLiteral("cancel") || aIsCancel)) {
+          presShell->FlushPendingNotifications(Flush_Layout);
+
+          // Get the frame again in case the flush caused it to go away
+          popupFrame = do_QueryFrame(aPopup->GetPrimaryFrame());
+          if (!popupFrame)
+            return;
+
+          if (nsLayoutUtils::HasCurrentTransitions(popupFrame)) {
+            RefPtr<TransitionEnder> ender = new TransitionEnder(aPopup, aDeselectMenu);
+            aPopup->AddSystemEventListener(NS_LITERAL_STRING("transitionend"),
+                                           ender, false, false);
+            return;
+          }
+        }
+      }
+#endif
+
+      HidePopupCallback(aPopup, popupFrame, aNextPopup, aLastPopup,
+                        aPopupType, aDeselectMenu);
+    }
+  }
+}
+
+bool
+nsXULPopupManager::IsPopupOpen(nsIContent* aPopup)
+{
+  // a popup is open if it is in the open list. The assertions ensure that the
+  // frame is in the correct state. If the popup is in the hiding or invisible
+  // state, it will still be in the open popup list until it is closed.
+  nsMenuChainItem* item = mPopups;
+  while (item) {
+    if (item->Content() == aPopup) {
+      NS_ASSERTION(item->Frame()->IsOpen() ||
+                   item->Frame()->PopupState() == ePopupHiding ||
+                   item->Frame()->PopupState() == ePopupInvisible,
+                   "popup in open list not actually open");
+      return true;
+    }
+    item = item->GetParent();
+  }
+
+  item = mNoHidePanels;
+  while (item) {
+    if (item->Content() == aPopup) {
+      NS_ASSERTION(item->Frame()->IsOpen() ||
+                   item->Frame()->PopupState() == ePopupHiding ||
+                   item->Frame()->PopupState() == ePopupInvisible,
+                   "popup in open list not actually open");
+      return true;
+    }
+    item = item->GetParent();
+  }
+
+  return false;
+}
+
+bool
+nsXULPopupManager::IsPopupOpenForMenuParent(nsMenuParent* aMenuParent)
+{
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  while (item) {
+    nsMenuPopupFrame* popup = item->Frame();
+    if (popup && popup->IsOpen()) {
+      nsMenuFrame* menuFrame = do_QueryFrame(popup->GetParent());
+      if (menuFrame && menuFrame->GetMenuParent() == aMenuParent) {
+        return true;
+      }
+    }
+    item = item->GetParent();
+  }
+
+  return false;
+}
+
+nsIFrame*
+nsXULPopupManager::GetTopPopup(nsPopupType aType)
+{
+  if ((aType == ePopupTypePanel || aType == ePopupTypeTooltip) && mNoHidePanels)
+    return mNoHidePanels->Frame();
+
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  while (item) {
+    if (item->PopupType() == aType || aType == ePopupTypeAny)
+      return item->Frame();
+    item = item->GetParent();
+  }
+
+  return nullptr;
+}
+
+void
+nsXULPopupManager::GetVisiblePopups(nsTArray<nsIFrame *>& aPopups)
+{
+  aPopups.Clear();
+
+  // Iterate over both lists of popups
+  nsMenuChainItem* item = mPopups;
+  for (int32_t list = 0; list < 2; list++) {
+    while (item) {
+      // Skip panels which are not visible as well as popups that
+      // are transparent to mouse events.
+      if (item->Frame()->IsVisible() && !item->Frame()->IsMouseTransparent()) {
+        aPopups.AppendElement(item->Frame());
+      }
+
+      item = item->GetParent();
+    }
+
+    item = mNoHidePanels;
+  }
+}
+
+already_AddRefed<nsIDOMNode>
+nsXULPopupManager::GetLastTriggerNode(nsIDocument* aDocument, bool aIsTooltip)
+{
+  if (!aDocument)
+    return nullptr;
+
+  nsCOMPtr<nsIDOMNode> node;
+
+  // if mOpeningPopup is set, it means that a popupshowing event is being
+  // fired. In this case, just use the cached node, as the popup is not yet in
+  // the list of open popups.
+  if (mOpeningPopup && mOpeningPopup->GetUncomposedDoc() == aDocument &&
+      aIsTooltip == mOpeningPopup->IsXULElement(nsGkAtoms::tooltip)) {
+    node = do_QueryInterface(nsMenuPopupFrame::GetTriggerContent(GetPopupFrameForContent(mOpeningPopup, false)));
+  }
+  else {
+    nsMenuChainItem* item = aIsTooltip ? mNoHidePanels : mPopups;
+    while (item) {
+      // look for a popup of the same type and document.
+      if ((item->PopupType() == ePopupTypeTooltip) == aIsTooltip &&
+          item->Content()->GetUncomposedDoc() == aDocument) {
+        node = do_QueryInterface(nsMenuPopupFrame::GetTriggerContent(item->Frame()));
+        if (node)
+          break;
+      }
+      item = item->GetParent();
+    }
+  }
+
+  return node.forget();
+}
+
+bool
+nsXULPopupManager::MayShowPopup(nsMenuPopupFrame* aPopup)
+{
+  // if a popup's IsOpen method returns true, then the popup must always be in
+  // the popup chain scanned in IsPopupOpen.
+  NS_ASSERTION(!aPopup->IsOpen() || IsPopupOpen(aPopup->GetContent()),
+               "popup frame state doesn't match XULPopupManager open state");
+
+  nsPopupState state = aPopup->PopupState();
+
+  // if the popup is not in the open popup chain, then it must have a state that
+  // is either closed, in the process of being shown, or invisible.
+  NS_ASSERTION(IsPopupOpen(aPopup->GetContent()) || state == ePopupClosed ||
+               state == ePopupShowing || state == ePopupPositioning ||
+               state == ePopupInvisible,
+               "popup not in XULPopupManager open list is open");
+
+  // don't show popups unless they are closed or invisible
+  if (state != ePopupClosed && state != ePopupInvisible)
+    return false;
+
+  // Don't show popups that we already have in our popup chain
+  if (IsPopupOpen(aPopup->GetContent())) {
+    NS_WARNING("Refusing to show duplicate popup");
+    return false;
+  }
+
+  // if the popup was just rolled up, don't reopen it
+  nsCOMPtr<nsIWidget> widget = aPopup->GetWidget();
+  if (widget && widget->GetLastRollup() == aPopup->GetContent())
+      return false;
+
+  nsCOMPtr<nsIDocShellTreeItem> dsti = aPopup->PresContext()->GetDocShell();
+  nsCOMPtr<nsIBaseWindow> baseWin = do_QueryInterface(dsti);
+  if (!baseWin)
+    return false;
+
+  nsCOMPtr<nsIDocShellTreeItem> root;
+  dsti->GetRootTreeItem(getter_AddRefs(root));
+  if (!root) {
+    return false;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> rootWin = root->GetWindow();
+
+  // chrome shells can always open popups, but other types of shells can only
+  // open popups when they are focused and visible
+  if (dsti->ItemType() != nsIDocShellTreeItem::typeChrome) {
+    // only allow popups in active windows
+    nsIFocusManager* fm = nsFocusManager::GetFocusManager();
+    if (!fm || !rootWin)
+      return false;
+
+    nsCOMPtr<mozIDOMWindowProxy> activeWindow;
+    fm->GetActiveWindow(getter_AddRefs(activeWindow));
+    if (activeWindow != rootWin)
+      return false;
+
+    // only allow popups in visible frames
+    bool visible;
+    baseWin->GetVisibility(&visible);
+    if (!visible)
+      return false;
+  }
+
+  // platforms respond differently when an popup is opened in a minimized
+  // window, so this is always disabled.
+  nsCOMPtr<nsIWidget> mainWidget;
+  baseWin->GetMainWidget(getter_AddRefs(mainWidget));
+  if (mainWidget && mainWidget->SizeMode() == nsSizeMode_Minimized) {
+    return false;
+  }
+
+#ifdef XP_MACOSX
+  if (rootWin) {
+    auto globalWin = nsGlobalWindow::Cast(rootWin.get());
+    if (globalWin->IsInModalState()) {
+      return false;
+    }
+  }
+#endif
+
+  // cannot open a popup that is a submenu of a menupopup that isn't open.
+  nsMenuFrame* menuFrame = do_QueryFrame(aPopup->GetParent());
+  if (menuFrame) {
+    nsMenuParent* parentPopup = menuFrame->GetMenuParent();
+    if (parentPopup && !parentPopup->IsOpen())
+      return false;
+  }
+
+  return true;
+}
+
+void
+nsXULPopupManager::PopupDestroyed(nsMenuPopupFrame* aPopup)
+{
+  // when a popup frame is destroyed, just unhook it from the list of popups
+  if (mTimerMenu == aPopup) {
+    if (mCloseTimer) {
+      mCloseTimer->Cancel();
+      mCloseTimer = nullptr;
+    }
+    mTimerMenu = nullptr;
+  }
+
+  nsMenuChainItem* item = mNoHidePanels;
+  while (item) {
+    if (item->Frame() == aPopup) {
+      item->Detach(&mNoHidePanels);
+      delete item;
+      break;
+    }
+    item = item->GetParent();
+  }
+
+  nsTArray<nsMenuPopupFrame *> popupsToHide;
+
+  item = mPopups;
+  while (item) {
+    nsMenuPopupFrame* frame = item->Frame();
+    if (frame == aPopup) {
+      if (frame->PopupState() != ePopupInvisible) {
+        // Iterate through any child menus and hide them as well, since the
+        // parent is going away. We won't remove them from the list yet, just
+        // hide them, as they will be removed from the list when this function
+        // gets called for that child frame.
+        nsMenuChainItem* child = item->GetChild();
+        while (child) {
+          // if the popup is a child frame of the menu that was destroyed, add
+          // it to the list of popups to hide. Don't bother with the events
+          // since the frames are going away. If the child menu is not a child
+          // frame, for example, a context menu, use HidePopup instead, but call
+          // it asynchronously since we are in the middle of frame destruction.
+          nsMenuPopupFrame* childframe = child->Frame();
+          if (nsLayoutUtils::IsProperAncestorFrame(frame, childframe)) {
+            popupsToHide.AppendElement(childframe);
+          }
+          else {
+            // HidePopup will take care of hiding any of its children, so
+            // break out afterwards
+            HidePopup(child->Content(), false, false, true, false);
+            break;
+          }
+
+          child = child->GetChild();
+        }
+      }
+
+      item->Detach(&mPopups);
+      delete item;
+      break;
+    }
+
+    item = item->GetParent();
+  }
+
+  HidePopupsInList(popupsToHide);
+}
+
+bool
+nsXULPopupManager::HasContextMenu(nsMenuPopupFrame* aPopup)
+{
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  while (item && item->Frame() != aPopup) {
+    if (item->IsContextMenu())
+      return true;
+    item = item->GetParent();
+  }
+
+  return false;
+}
+
+void
+nsXULPopupManager::SetCaptureState(nsIContent* aOldPopup)
+{
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  if (item && aOldPopup == item->Content())
+    return;
+
+  if (mWidget) {
+    mWidget->CaptureRollupEvents(nullptr, false);
+    mWidget = nullptr;
+  }
+
+  if (item) {
+    nsMenuPopupFrame* popup = item->Frame();
+    mWidget = popup->GetWidget();
+    if (mWidget) {
+      mWidget->CaptureRollupEvents(nullptr, true);
+      popup->AttachedDismissalListener();
+    }
+  }
+
+  UpdateKeyboardListeners();
+}
+
+void
+nsXULPopupManager::UpdateKeyboardListeners()
+{
+  nsCOMPtr<EventTarget> newTarget;
+  bool isForMenu = false;
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  if (item) {
+    if (item->IgnoreKeys() != eIgnoreKeys_True) {
+      newTarget = item->Content()->GetComposedDoc();
+    }
+    isForMenu = item->PopupType() == ePopupTypeMenu;
+  }
+  else if (mActiveMenuBar) {
+    newTarget = mActiveMenuBar->GetContent()->GetComposedDoc();
+    isForMenu = true;
+  }
+
+  if (mKeyListener != newTarget) {
+    if (mKeyListener) {
+      mKeyListener->RemoveEventListener(NS_LITERAL_STRING("keypress"), this, true);
+      mKeyListener->RemoveEventListener(NS_LITERAL_STRING("keydown"), this, true);
+      mKeyListener->RemoveEventListener(NS_LITERAL_STRING("keyup"), this, true);
+      mKeyListener = nullptr;
+      nsContentUtils::NotifyInstalledMenuKeyboardListener(false);
+    }
+
+    if (newTarget) {
+      newTarget->AddEventListener(NS_LITERAL_STRING("keypress"), this, true);
+      newTarget->AddEventListener(NS_LITERAL_STRING("keydown"), this, true);
+      newTarget->AddEventListener(NS_LITERAL_STRING("keyup"), this, true);
+      nsContentUtils::NotifyInstalledMenuKeyboardListener(isForMenu);
+      mKeyListener = newTarget;
+    }
+  }
+}
+
+void
+nsXULPopupManager::UpdateMenuItems(nsIContent* aPopup)
+{
+  // Walk all of the menu's children, checking to see if any of them has a
+  // command attribute. If so, then several attributes must potentially be updated.
+
+  nsCOMPtr<nsIDocument> document = aPopup->GetUncomposedDoc();
+  if (!document) {
+    return;
+  }
+
+  for (nsCOMPtr<nsIContent> grandChild = aPopup->GetFirstChild();
+       grandChild;
+       grandChild = grandChild->GetNextSibling()) {
+    if (grandChild->IsXULElement(nsGkAtoms::menugroup)) {
+      if (grandChild->GetChildCount() == 0) {
+        continue;
+      }
+      grandChild = grandChild->GetFirstChild();
+    }
+    if (grandChild->IsXULElement(nsGkAtoms::menuitem)) {
+      // See if we have a command attribute.
+      nsAutoString command;
+      grandChild->GetAttr(kNameSpaceID_None, nsGkAtoms::command, command);
+      if (!command.IsEmpty()) {
+        // We do! Look it up in our document
+        RefPtr<dom::Element> commandElement =
+          document->GetElementById(command);
+        if (commandElement) {
+          nsAutoString commandValue;
+          // The menu's disabled state needs to be updated to match the command.
+          if (commandElement->GetAttr(kNameSpaceID_None, nsGkAtoms::disabled, commandValue))
+            grandChild->SetAttr(kNameSpaceID_None, nsGkAtoms::disabled, commandValue, true);
+          else
+            grandChild->UnsetAttr(kNameSpaceID_None, nsGkAtoms::disabled, true);
+
+          // The menu's label, accesskey checked and hidden states need to be updated
+          // to match the command. Note that unlike the disabled state if the
+          // command has *no* value, we assume the menu is supplying its own.
+          if (commandElement->GetAttr(kNameSpaceID_None, nsGkAtoms::label, commandValue))
+            grandChild->SetAttr(kNameSpaceID_None, nsGkAtoms::label, commandValue, true);
+
+          if (commandElement->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, commandValue))
+            grandChild->SetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, commandValue, true);
+
+          if (commandElement->GetAttr(kNameSpaceID_None, nsGkAtoms::checked, commandValue))
+            grandChild->SetAttr(kNameSpaceID_None, nsGkAtoms::checked, commandValue, true);
+
+          if (commandElement->GetAttr(kNameSpaceID_None, nsGkAtoms::hidden, commandValue))
+            grandChild->SetAttr(kNameSpaceID_None, nsGkAtoms::hidden, commandValue, true);
+        }
+      }
+    }
+    if (!grandChild->GetNextSibling() &&
+        grandChild->GetParent()->IsXULElement(nsGkAtoms::menugroup)) {
+      grandChild = grandChild->GetParent();
+    }
+  }
+}
+
+// Notify
+//
+// The item selection timer has fired, we might have to readjust the 
+// selected item. There are two cases here that we are trying to deal with:
+//   (1) diagonal movement from a parent menu to a submenu passing briefly over
+//       other items, and
+//   (2) moving out from a submenu to a parent or grandparent menu.
+// In both cases, |mTimerMenu| is the menu item that might have an open submenu and
+// the first item in |mPopups| is the item the mouse is currently over, which could be
+// none of them.
+//
+// case (1):
+//  As the mouse moves from the parent item of a submenu (we'll call 'A') diagonally into the
+//  submenu, it probably passes through one or more sibilings (B). As the mouse passes
+//  through B, it becomes the current menu item and the timer is set and mTimerMenu is 
+//  set to A. Before the timer fires, the mouse leaves the menu containing A and B and
+//  enters the submenus. Now when the timer fires, |mPopups| is null (!= |mTimerMenu|)
+//  so we have to see if anything in A's children is selected (recall that even disabled
+//  items are selected, the style just doesn't show it). If that is the case, we need to
+//  set the selected item back to A.
+//
+// case (2);
+//  Item A has an open submenu, and in it there is an item (B) which also has an open
+//  submenu (so there are 3 menus displayed right now). The mouse then leaves B's child
+//  submenu and selects an item that is a sibling of A, call it C. When the mouse enters C,
+//  the timer is set and |mTimerMenu| is A and |mPopups| is C. As the timer fires,
+//  the mouse is still within C. The correct behavior is to set the current item to C
+//  and close up the chain parented at A.
+//
+//  This brings up the question of is the logic of case (1) enough? The answer is no,
+//  and is discussed in bugzilla bug 29400. Case (1) asks if A's submenu has a selected
+//  child, and if it does, set the selected item to A. Because B has a submenu open, it
+//  is selected and as a result, A is set to be the selected item even though the mouse
+//  rests in C -- very wrong. 
+//
+//  The solution is to use the same idea, but instead of only checking one level, 
+//  drill all the way down to the deepest open submenu and check if it has something 
+//  selected. Since the mouse is in a grandparent, it won't, and we know that we can
+//  safely close up A and all its children.
+//
+// The code below melds the two cases together.
+//
+nsresult
+nsXULPopupManager::Notify(nsITimer* aTimer)
+{
+  if (aTimer == mCloseTimer)
+    KillMenuTimer();
+
+  return NS_OK;
+}
+
+void
+nsXULPopupManager::KillMenuTimer()
+{
+  if (mCloseTimer && mTimerMenu) {
+    mCloseTimer->Cancel();
+    mCloseTimer = nullptr;
+
+    if (mTimerMenu->IsOpen())
+      HidePopup(mTimerMenu->GetContent(), false, false, true, false);
+  }
+
+  mTimerMenu = nullptr;
+}
+
+void
+nsXULPopupManager::CancelMenuTimer(nsMenuParent* aMenuParent)
+{
+  if (mCloseTimer && mTimerMenu == aMenuParent) {
+    mCloseTimer->Cancel();
+    mCloseTimer = nullptr;
+    mTimerMenu = nullptr;
+  }
+}
+
+bool
+nsXULPopupManager::HandleShortcutNavigation(nsIDOMKeyEvent* aKeyEvent,
+                                            nsMenuPopupFrame* aFrame)
+{
+  // On Windows, don't check shortcuts when the accelerator key is down.
+#ifdef XP_WIN
+  WidgetInputEvent* evt = aKeyEvent->AsEvent()->WidgetEventPtr()->AsInputEvent();
+  if (evt && evt->IsAccel()) {
+    return false;
+  }
+#endif
+
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  if (!aFrame && item)
+    aFrame = item->Frame();
+
+  if (aFrame) {
+    bool action;
+    nsMenuFrame* result = aFrame->FindMenuWithShortcut(aKeyEvent, action);
+    if (result) {
+      aFrame->ChangeMenuItem(result, false, true);
+      if (action) {
+        WidgetGUIEvent* evt = aKeyEvent->AsEvent()->WidgetEventPtr()->AsGUIEvent();
+        nsMenuFrame* menuToOpen = result->Enter(evt);
+        if (menuToOpen) {
+          nsCOMPtr<nsIContent> content = menuToOpen->GetContent();
+          ShowMenu(content, true, false);
+        }
+      }
+      return true;
+    }
+
+    return false;
+  }
+
+  if (mActiveMenuBar) {
+    nsMenuFrame* result = mActiveMenuBar->FindMenuWithShortcut(aKeyEvent);
+    if (result) {
+      mActiveMenuBar->SetActive(true);
+      result->OpenMenu(true);
+      return true;
+    }
+  }
+
+  return false;
+}
+
+
+bool
+nsXULPopupManager::HandleKeyboardNavigation(uint32_t aKeyCode)
+{
+  // navigate up through the open menus, looking for the topmost one
+  // in the same hierarchy
+  nsMenuChainItem* item = nullptr;
+  nsMenuChainItem* nextitem = GetTopVisibleMenu();
+
+  while (nextitem) {
+    item = nextitem;
+    nextitem = item->GetParent();
+
+    if (nextitem) {
+      // stop if the parent isn't a menu
+      if (!nextitem->IsMenu())
+        break;
+
+      // check to make sure that the parent is actually the parent menu. It won't
+      // be if the parent is in a different frame hierarchy, for example, for a
+      // context menu opened on another menu.
+      nsMenuParent* expectedParent = static_cast<nsMenuParent *>(nextitem->Frame());
+      nsMenuFrame* menuFrame = do_QueryFrame(item->Frame()->GetParent());
+      if (!menuFrame || menuFrame->GetMenuParent() != expectedParent) {
+        break;
+      }
+    }
+  }
+
+  nsIFrame* itemFrame;
+  if (item)
+    itemFrame = item->Frame();
+  else if (mActiveMenuBar)
+    itemFrame = mActiveMenuBar;
+  else
+    return false;
+
+  nsNavigationDirection theDirection;
+  NS_ASSERTION(aKeyCode >= nsIDOMKeyEvent::DOM_VK_END &&
+                 aKeyCode <= nsIDOMKeyEvent::DOM_VK_DOWN, "Illegal key code");
+  theDirection = NS_DIRECTION_FROM_KEY_CODE(itemFrame, aKeyCode);
+
+  // if a popup is open, first check for navigation within the popup
+  if (item && HandleKeyboardNavigationInPopup(item, theDirection))
+    return true;
+
+  // no popup handled the key, so check the active menubar, if any
+  if (mActiveMenuBar) {
+    nsMenuFrame* currentMenu = mActiveMenuBar->GetCurrentMenuItem();
+  
+    if (NS_DIRECTION_IS_INLINE(theDirection)) {
+      nsMenuFrame* nextItem = (theDirection == eNavigationDirection_End) ?
+                              GetNextMenuItem(mActiveMenuBar, currentMenu, false) : 
+                              GetPreviousMenuItem(mActiveMenuBar, currentMenu, false);
+      mActiveMenuBar->ChangeMenuItem(nextItem, true, true);
+      return true;
+    }
+    else if (NS_DIRECTION_IS_BLOCK(theDirection)) {
+      // Open the menu and select its first item.
+      if (currentMenu) {
+        nsCOMPtr<nsIContent> content = currentMenu->GetContent();
+        ShowMenu(content, true, false);
+      }
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+nsXULPopupManager::HandleKeyboardNavigationInPopup(nsMenuChainItem* item,
+                                                   nsMenuPopupFrame* aFrame,
+                                                   nsNavigationDirection aDir)
+{
+  NS_ASSERTION(aFrame, "aFrame is null");
+  NS_ASSERTION(!item || item->Frame() == aFrame,
+               "aFrame is expected to be equal to item->Frame()");
+
+  nsMenuFrame* currentMenu = aFrame->GetCurrentMenuItem();
+
+  aFrame->ClearIncrementalString();
+
+  // This method only gets called if we're open.
+  if (!currentMenu && NS_DIRECTION_IS_INLINE(aDir)) {
+    // We've been opened, but we haven't had anything selected.
+    // We can handle End, but our parent handles Start.
+    if (aDir == eNavigationDirection_End) {
+      nsMenuFrame* nextItem = GetNextMenuItem(aFrame, nullptr, true);
+      if (nextItem) {
+        aFrame->ChangeMenuItem(nextItem, false, true);
+        return true;
+      }
+    }
+    return false;
+  }
+
+  bool isContainer = false;
+  bool isOpen = false;
+  if (currentMenu) {
+    isOpen = currentMenu->IsOpen();
+    isContainer = currentMenu->IsMenu();
+    if (isOpen) {
+      // for an open popup, have the child process the event
+      nsMenuChainItem* child = item ? item->GetChild() : nullptr;
+      if (child && HandleKeyboardNavigationInPopup(child, aDir))
+        return true;
+    }
+    else if (aDir == eNavigationDirection_End &&
+             isContainer && !currentMenu->IsDisabled()) {
+      // The menu is not yet open. Open it and select the first item.
+      nsCOMPtr<nsIContent> content = currentMenu->GetContent();
+      ShowMenu(content, true, false);
+      return true;
+    }
+  }
+
+  // For block progression, we can move in either direction
+  if (NS_DIRECTION_IS_BLOCK(aDir) ||
+      NS_DIRECTION_IS_BLOCK_TO_EDGE(aDir)) {
+    nsMenuFrame* nextItem;
+
+    if (aDir == eNavigationDirection_Before)
+      nextItem = GetPreviousMenuItem(aFrame, currentMenu, true);
+    else if (aDir == eNavigationDirection_After)
+      nextItem = GetNextMenuItem(aFrame, currentMenu, true);
+    else if (aDir == eNavigationDirection_First)
+      nextItem = GetNextMenuItem(aFrame, nullptr, true);
+    else
+      nextItem = GetPreviousMenuItem(aFrame, nullptr, true);
+
+    if (nextItem) {
+      aFrame->ChangeMenuItem(nextItem, false, true);
+      return true;
+    }
+  }
+  else if (currentMenu && isContainer && isOpen) {
+    if (aDir == eNavigationDirection_Start) {
+      // close a submenu when Left is pressed
+      nsMenuPopupFrame* popupFrame = currentMenu->GetPopup();
+      if (popupFrame)
+        HidePopup(popupFrame->GetContent(), false, false, false, false);
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+nsXULPopupManager::HandleKeyboardEventWithKeyCode(
+                        nsIDOMKeyEvent* aKeyEvent,
+                        nsMenuChainItem* aTopVisibleMenuItem)
+{
+  uint32_t keyCode;
+  aKeyEvent->GetKeyCode(&keyCode);
+
+  // Escape should close panels, but the other keys should have no effect.
+  if (aTopVisibleMenuItem &&
+      aTopVisibleMenuItem->PopupType() != ePopupTypeMenu) {
+    if (keyCode == nsIDOMKeyEvent::DOM_VK_ESCAPE) {
+      HidePopup(aTopVisibleMenuItem->Content(), false, false, false, true);
+      aKeyEvent->AsEvent()->StopPropagation();
+      aKeyEvent->AsEvent()->StopCrossProcessForwarding();
+      aKeyEvent->AsEvent()->PreventDefault();
+    }
+    return true;
+  }
+
+  bool consume = (mPopups || mActiveMenuBar);
+  switch (keyCode) {
+    case nsIDOMKeyEvent::DOM_VK_UP:
+    case nsIDOMKeyEvent::DOM_VK_DOWN:
+#ifndef XP_MACOSX
+      // roll up the popup when alt+up/down are pressed within a menulist.
+      bool alt;
+      aKeyEvent->GetAltKey(&alt);
+      if (alt && aTopVisibleMenuItem && aTopVisibleMenuItem->Frame()->IsMenuList()) {
+        Rollup(0, false, nullptr, nullptr);
+        break;
+      }
+      MOZ_FALLTHROUGH;
+#endif
+
+    case nsIDOMKeyEvent::DOM_VK_LEFT:
+    case nsIDOMKeyEvent::DOM_VK_RIGHT:
+    case nsIDOMKeyEvent::DOM_VK_HOME:
+    case nsIDOMKeyEvent::DOM_VK_END:
+      HandleKeyboardNavigation(keyCode);
+      break;
+
+    case nsIDOMKeyEvent::DOM_VK_PAGE_DOWN:
+    case nsIDOMKeyEvent::DOM_VK_PAGE_UP:
+      if (aTopVisibleMenuItem) {
+        aTopVisibleMenuItem->Frame()->ChangeByPage(keyCode == nsIDOMKeyEvent::DOM_VK_PAGE_UP);
+      }
+      break;
+
+    case nsIDOMKeyEvent::DOM_VK_ESCAPE:
+      // Pressing Escape hides one level of menus only. If no menu is open,
+      // check if a menubar is active and inform it that a menu closed. Even
+      // though in this latter case, a menu didn't actually close, the effect
+      // ends up being the same. Similar for the tab key below.
+      if (aTopVisibleMenuItem) {
+        HidePopup(aTopVisibleMenuItem->Content(), false, false, false, true);
+      } else if (mActiveMenuBar) {
+        mActiveMenuBar->MenuClosed();
+      }
+      break;
+
+    case nsIDOMKeyEvent::DOM_VK_TAB:
+#ifndef XP_MACOSX
+    case nsIDOMKeyEvent::DOM_VK_F10:
+#endif
+      if (aTopVisibleMenuItem &&
+          !aTopVisibleMenuItem->Frame()->GetContent()->AttrValueIs(kNameSpaceID_None,
+           nsGkAtoms::activateontab, nsGkAtoms::_true, eCaseMatters)) {
+        // close popups or deactivate menubar when Tab or F10 are pressed
+        Rollup(0, false, nullptr, nullptr);
+        break;
+      } else if (mActiveMenuBar) {
+        mActiveMenuBar->MenuClosed();
+        break;
+      }
+      // Intentional fall-through to RETURN case
+      MOZ_FALLTHROUGH;
+
+    case nsIDOMKeyEvent::DOM_VK_RETURN: {
+      // If there is a popup open, check if the current item needs to be opened.
+      // Otherwise, tell the active menubar, if any, to activate the menu. The
+      // Enter method will return a menu if one needs to be opened as a result.
+      nsMenuFrame* menuToOpen = nullptr;
+      WidgetGUIEvent* GUIEvent = aKeyEvent->AsEvent()->
+        WidgetEventPtr()->AsGUIEvent();
+
+      if (aTopVisibleMenuItem) {
+        menuToOpen = aTopVisibleMenuItem->Frame()->Enter(GUIEvent);
+      } else if (mActiveMenuBar) {
+        menuToOpen = mActiveMenuBar->Enter(GUIEvent);
+      }
+      if (menuToOpen) {
+        nsCOMPtr<nsIContent> content = menuToOpen->GetContent();
+        ShowMenu(content, true, false);
+      }
+      break;
+    }
+
+    default:
+      return false;
+  }
+
+  if (consume) {
+    aKeyEvent->AsEvent()->StopPropagation();
+    aKeyEvent->AsEvent()->StopCrossProcessForwarding();
+    aKeyEvent->AsEvent()->PreventDefault();
+  }
+  return true;
+}
+
+nsMenuFrame*
+nsXULPopupManager::GetNextMenuItem(nsContainerFrame* aParent,
+                                   nsMenuFrame* aStart,
+                                   bool aIsPopup)
+{
+  nsPresContext* presContext = aParent->PresContext();
+  auto insertion = presContext->PresShell()->
+    FrameConstructor()->GetInsertionPoint(aParent->GetContent(), nullptr);
+  nsContainerFrame* immediateParent = insertion.mParentFrame;
+  if (!immediateParent)
+    immediateParent = aParent;
+
+  nsIFrame* currFrame = nullptr;
+  if (aStart) {
+    if (aStart->GetNextSibling())
+      currFrame = aStart->GetNextSibling();
+    else if (aStart->GetParent()->GetContent()->IsXULElement(nsGkAtoms::menugroup))
+      currFrame = aStart->GetParent()->GetNextSibling();
+  }
+  else
+    currFrame = immediateParent->PrincipalChildList().FirstChild();
+
+  while (currFrame) {
+    // See if it's a menu item.
+    nsIContent* currFrameContent = currFrame->GetContent();
+    if (IsValidMenuItem(currFrameContent, aIsPopup)) {
+      return do_QueryFrame(currFrame);
+    }
+    if (currFrameContent->IsXULElement(nsGkAtoms::menugroup) &&
+        currFrameContent->GetChildCount() > 0)
+      currFrame = currFrame->PrincipalChildList().FirstChild();
+    else if (!currFrame->GetNextSibling() &&
+             currFrame->GetParent()->GetContent()->IsXULElement(nsGkAtoms::menugroup))
+      currFrame = currFrame->GetParent()->GetNextSibling();
+    else
+      currFrame = currFrame->GetNextSibling();
+  }
+
+  currFrame = immediateParent->PrincipalChildList().FirstChild();
+
+  // Still don't have anything. Try cycling from the beginning.
+  while (currFrame && currFrame != aStart) {
+    // See if it's a menu item.
+    nsIContent* currFrameContent = currFrame->GetContent();
+    if (IsValidMenuItem(currFrameContent, aIsPopup)) {
+      return do_QueryFrame(currFrame);
+    }
+    if (currFrameContent->IsXULElement(nsGkAtoms::menugroup) &&
+        currFrameContent->GetChildCount() > 0)
+      currFrame = currFrame->PrincipalChildList().FirstChild();
+    else if (!currFrame->GetNextSibling() &&
+             currFrame->GetParent()->GetContent()->IsXULElement(nsGkAtoms::menugroup))
+      currFrame = currFrame->GetParent()->GetNextSibling();
+    else
+      currFrame = currFrame->GetNextSibling();
+  }
+
+  // No luck. Just return our start value.
+  return aStart;
+}
+
+nsMenuFrame*
+nsXULPopupManager::GetPreviousMenuItem(nsContainerFrame* aParent,
+                                       nsMenuFrame* aStart,
+                                       bool aIsPopup)
+{
+  nsPresContext* presContext = aParent->PresContext();
+  auto insertion = presContext->PresShell()->
+    FrameConstructor()->GetInsertionPoint(aParent->GetContent(), nullptr);
+  nsContainerFrame* immediateParent = insertion.mParentFrame;
+  if (!immediateParent)
+    immediateParent = aParent;
+
+  const nsFrameList& frames(immediateParent->PrincipalChildList());
+
+  nsIFrame* currFrame = nullptr;
+  if (aStart) {
+    if (aStart->GetPrevSibling())
+      currFrame = aStart->GetPrevSibling();
+    else if (aStart->GetParent()->GetContent()->IsXULElement(nsGkAtoms::menugroup))
+      currFrame = aStart->GetParent()->GetPrevSibling();
+  }
+  else
+    currFrame = frames.LastChild();
+
+  while (currFrame) {
+    // See if it's a menu item.
+    nsIContent* currFrameContent = currFrame->GetContent();
+    if (IsValidMenuItem(currFrameContent, aIsPopup)) {
+      return do_QueryFrame(currFrame);
+    }
+    if (currFrameContent->IsXULElement(nsGkAtoms::menugroup) &&
+        currFrameContent->GetChildCount() > 0) {
+      const nsFrameList& menugroupFrames(currFrame->PrincipalChildList());
+      currFrame = menugroupFrames.LastChild();
+    }
+    else if (!currFrame->GetPrevSibling() &&
+             currFrame->GetParent()->GetContent()->IsXULElement(nsGkAtoms::menugroup))
+      currFrame = currFrame->GetParent()->GetPrevSibling();
+    else
+      currFrame = currFrame->GetPrevSibling();
+  }
+
+  currFrame = frames.LastChild();
+
+  // Still don't have anything. Try cycling from the end.
+  while (currFrame && currFrame != aStart) {
+    // See if it's a menu item.
+    nsIContent* currFrameContent = currFrame->GetContent();
+    if (IsValidMenuItem(currFrameContent, aIsPopup)) {
+      return do_QueryFrame(currFrame);
+    }
+    if (currFrameContent->IsXULElement(nsGkAtoms::menugroup) &&
+        currFrameContent->GetChildCount() > 0) {
+      const nsFrameList& menugroupFrames(currFrame->PrincipalChildList());
+      currFrame = menugroupFrames.LastChild();
+    }
+    else if (!currFrame->GetPrevSibling() &&
+             currFrame->GetParent()->GetContent()->IsXULElement(nsGkAtoms::menugroup))
+      currFrame = currFrame->GetParent()->GetPrevSibling();
+    else
+      currFrame = currFrame->GetPrevSibling();
+  }
+
+  // No luck. Just return our start value.
+  return aStart;
+}
+
+bool
+nsXULPopupManager::IsValidMenuItem(nsIContent* aContent, bool aOnPopup)
+{
+  if (aContent->IsXULElement()) {
+    if (!aContent->IsAnyOfXULElements(nsGkAtoms::menu, nsGkAtoms::menuitem)) {
+      return false;
+    }
+  }
+  else if (!aOnPopup || !aContent->IsHTMLElement(nsGkAtoms::option)) {
+    return false;
+  }
+
+  nsMenuFrame* menuFrame = do_QueryFrame(aContent->GetPrimaryFrame());
+
+  bool skipNavigatingDisabledMenuItem = true;
+  if (aOnPopup && (!menuFrame || menuFrame->GetParentMenuListType() == eNotMenuList)) {
+    skipNavigatingDisabledMenuItem =
+      LookAndFeel::GetInt(LookAndFeel::eIntID_SkipNavigatingDisabledMenuItem,
+                          0) != 0;
+  }
+
+  return !(skipNavigatingDisabledMenuItem &&
+           aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                                 nsGkAtoms::_true, eCaseMatters));
+}
+
+nsresult
+nsXULPopupManager::HandleEvent(nsIDOMEvent* aEvent)
+{
+  nsCOMPtr<nsIDOMKeyEvent> keyEvent = do_QueryInterface(aEvent);
+  NS_ENSURE_TRUE(keyEvent, NS_ERROR_UNEXPECTED);
+
+  //handlers shouldn't be triggered by non-trusted events.
+  bool trustedEvent = false;
+  aEvent->GetIsTrusted(&trustedEvent);
+  if (!trustedEvent) {
+    return NS_OK;
+  }
+
+  nsAutoString eventType;
+  aEvent->GetType(eventType);
+  if (eventType.EqualsLiteral("keyup")) {
+    return KeyUp(keyEvent);
+  }
+  if (eventType.EqualsLiteral("keydown")) {
+    return KeyDown(keyEvent);
+  }
+  if (eventType.EqualsLiteral("keypress")) {
+    return KeyPress(keyEvent);
+  }
+
+  NS_ABORT();
+
+  return NS_OK;
+}
+
+nsresult
+nsXULPopupManager::KeyUp(nsIDOMKeyEvent* aKeyEvent)
+{
+  // don't do anything if a menu isn't open or a menubar isn't active
+  if (!mActiveMenuBar) {
+    nsMenuChainItem* item = GetTopVisibleMenu();
+    if (!item || item->PopupType() != ePopupTypeMenu)
+      return NS_OK;
+
+    if (item->IgnoreKeys() == eIgnoreKeys_Shortcuts) {
+      aKeyEvent->AsEvent()->StopCrossProcessForwarding();
+      return NS_OK;
+    }
+  }
+
+  aKeyEvent->AsEvent()->StopPropagation();
+  aKeyEvent->AsEvent()->StopCrossProcessForwarding();
+  aKeyEvent->AsEvent()->PreventDefault();
+
+  return NS_OK; // I am consuming event
+}
+
+nsresult
+nsXULPopupManager::KeyDown(nsIDOMKeyEvent* aKeyEvent)
+{
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  if (item && item->Frame()->IsMenuLocked())
+    return NS_OK;
+
+  if (HandleKeyboardEventWithKeyCode(aKeyEvent, item)) {
+    return NS_OK;
+  }
+
+  // don't do anything if a menu isn't open or a menubar isn't active
+  if (!mActiveMenuBar && (!item || item->PopupType() != ePopupTypeMenu))
+    return NS_OK;
+
+  // Since a menu was open, stop propagation of the event to keep other event
+  // listeners from becoming confused.
+  if (!item || item->IgnoreKeys() != eIgnoreKeys_Shortcuts) {
+    aKeyEvent->AsEvent()->StopPropagation();
+  }
+
+  int32_t menuAccessKey = -1;
+
+  // If the key just pressed is the access key (usually Alt),
+  // dismiss and unfocus the menu.
+
+  nsMenuBarListener::GetMenuAccessKey(&menuAccessKey);
+  if (menuAccessKey) {
+    uint32_t theChar;
+    aKeyEvent->GetKeyCode(&theChar);
+
+    if (theChar == (uint32_t)menuAccessKey) {
+      bool ctrl = false;
+      if (menuAccessKey != nsIDOMKeyEvent::DOM_VK_CONTROL)
+        aKeyEvent->GetCtrlKey(&ctrl);
+      bool alt=false;
+      if (menuAccessKey != nsIDOMKeyEvent::DOM_VK_ALT)
+        aKeyEvent->GetAltKey(&alt);
+      bool shift=false;
+      if (menuAccessKey != nsIDOMKeyEvent::DOM_VK_SHIFT)
+        aKeyEvent->GetShiftKey(&shift);
+      bool meta=false;
+      if (menuAccessKey != nsIDOMKeyEvent::DOM_VK_META)
+        aKeyEvent->GetMetaKey(&meta);
+      if (!(ctrl || alt || shift || meta)) {
+        // The access key just went down and no other
+        // modifiers are already down.
+        nsMenuChainItem* item = GetTopVisibleMenu();
+        if (mPopups && item && !item->Frame()->IsMenuList()) {
+          Rollup(0, false, nullptr, nullptr);
+        } else if (mActiveMenuBar) {
+          mActiveMenuBar->MenuClosed();
+        }
+
+        // Clear the item to avoid bugs as it may have been deleted during rollup.
+        item = nullptr; 
+      }
+      aKeyEvent->AsEvent()->StopPropagation();
+      aKeyEvent->AsEvent()->PreventDefault();
+    }
+  }
+
+  aKeyEvent->AsEvent()->StopCrossProcessForwarding();
+  return NS_OK;
+}
+
+nsresult
+nsXULPopupManager::KeyPress(nsIDOMKeyEvent* aKeyEvent)
+{
+  // Don't check prevent default flag -- menus always get first shot at key events.
+
+  nsMenuChainItem* item = GetTopVisibleMenu();
+  if (item &&
+      (item->Frame()->IsMenuLocked() || item->PopupType() != ePopupTypeMenu)) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIDOMKeyEvent> keyEvent = do_QueryInterface(aKeyEvent);
+  NS_ENSURE_TRUE(keyEvent, NS_ERROR_UNEXPECTED);
+  // if a menu is open or a menubar is active, it consumes the key event
+  bool consume = (mPopups || mActiveMenuBar);
+
+  WidgetInputEvent* evt = aKeyEvent->AsEvent()->WidgetEventPtr()->AsInputEvent();
+  bool isAccel = evt && evt->IsAccel();
+
+  // When ignorekeys="shortcuts" is used, we don't call preventDefault on the
+  // key event when the accelerator key is pressed. This allows another
+  // listener to handle keys. For instance, this allows global shortcuts to
+  // still apply while a menu is open.
+  if (item && item->IgnoreKeys() == eIgnoreKeys_Shortcuts && isAccel) {
+    consume = false;
+  }
+
+  HandleShortcutNavigation(keyEvent, nullptr);
+
+  aKeyEvent->AsEvent()->StopCrossProcessForwarding();
+  if (consume) {
+    aKeyEvent->AsEvent()->StopPropagation();
+    aKeyEvent->AsEvent()->PreventDefault();
+  }
+
+  return NS_OK; // I am consuming event
+}
+
+NS_IMETHODIMP
+nsXULPopupShowingEvent::Run()
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm) {
+    pm->FirePopupShowingEvent(mPopup, mIsContextMenu, mSelectFirstItem);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULPopupHidingEvent::Run()
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+
+  nsIDocument *document = mPopup->GetUncomposedDoc();
+  if (pm && document) {
+    nsIPresShell* presShell = document->GetShell();
+    if (presShell) {
+      nsPresContext* context = presShell->GetPresContext();
+      if (context) {
+        pm->FirePopupHidingEvent(mPopup, mNextPopup, mLastPopup,
+                                 context, mPopupType, mDeselectMenu, mIsRollup);
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+bool
+nsXULPopupPositionedEvent::DispatchIfNeeded(nsIContent *aPopup,
+                                            bool aIsContextMenu,
+                                            bool aSelectFirstItem)
+{
+  // The popuppositioned event only fires on arrow panels for now.
+  if (aPopup->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                          nsGkAtoms::arrow, eCaseMatters)) {
+    nsCOMPtr<nsIRunnable> event =
+      new nsXULPopupPositionedEvent(aPopup, aIsContextMenu, aSelectFirstItem);
+    NS_DispatchToCurrentThread(event);
+
+    return true;
+  }
+
+  return false;
+}
+
+NS_IMETHODIMP
+nsXULPopupPositionedEvent::Run()
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm) {
+    nsMenuPopupFrame* popupFrame = do_QueryFrame(mPopup->GetPrimaryFrame());
+    if (popupFrame) {
+      // At this point, hidePopup may have been called but it currently has no
+      // way to stop this event. However, if hidePopup was called, the popup
+      // will now be in the hiding or closed state. If we are in the shown or
+      // positioning state instead, we can assume that we are still clear to
+      // open/move the popup
+      nsPopupState state = popupFrame->PopupState();
+      if (state != ePopupPositioning && state != ePopupShown) {
+        return NS_OK;
+      }
+      nsEventStatus status = nsEventStatus_eIgnore;
+      WidgetMouseEvent event(true, eXULPopupPositioned, nullptr,
+                             WidgetMouseEvent::eReal);
+      EventDispatcher::Dispatch(mPopup, popupFrame->PresContext(),
+                                &event, nullptr, &status);
+
+      // Get the popup frame and make sure it is still in the positioning
+      // state. If it isn't, someone may have tried to reshow or hide it
+      // during the popuppositioned event.
+      // Alternately, this event may have been fired in reponse to moving the
+      // popup rather than opening it. In that case, we are done.
+      nsMenuPopupFrame* popupFrame = do_QueryFrame(mPopup->GetPrimaryFrame());
+      if (popupFrame && popupFrame->PopupState() == ePopupPositioning) {
+        pm->ShowPopupCallback(mPopup, popupFrame, mIsContextMenu, mSelectFirstItem);
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULMenuCommandEvent::Run()
+{
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (!pm)
+    return NS_OK;
+
+  // The order of the nsViewManager and nsIPresShell COM pointers is
+  // important below.  We want the pres shell to get released before the
+  // associated view manager on exit from this function.
+  // See bug 54233.
+  // XXXndeakin is this still needed?
+
+  nsCOMPtr<nsIContent> popup;
+  nsMenuFrame* menuFrame = do_QueryFrame(mMenu->GetPrimaryFrame());
+  nsWeakFrame weakFrame(menuFrame);
+  if (menuFrame && mFlipChecked) {
+    if (menuFrame->IsChecked()) {
+      mMenu->UnsetAttr(kNameSpaceID_None, nsGkAtoms::checked, true);
+    } else {
+      mMenu->SetAttr(kNameSpaceID_None, nsGkAtoms::checked,
+                     NS_LITERAL_STRING("true"), true);
+    }
+  }
+
+  if (menuFrame && weakFrame.IsAlive()) {
+    // Find the popup that the menu is inside. Below, this popup will
+    // need to be hidden.
+    nsIFrame* frame = menuFrame->GetParent();
+    while (frame) {
+      nsMenuPopupFrame* popupFrame = do_QueryFrame(frame);
+      if (popupFrame) {
+        popup = popupFrame->GetContent();
+        break;
+      }
+      frame = frame->GetParent();
+    }
+
+    nsPresContext* presContext = menuFrame->PresContext();
+    nsCOMPtr<nsIPresShell> shell = presContext->PresShell();
+    RefPtr<nsViewManager> kungFuDeathGrip = shell->GetViewManager();
+    mozilla::Unused << kungFuDeathGrip; // Not referred to directly within this function
+
+    // Deselect ourselves.
+    if (mCloseMenuMode != CloseMenuMode_None)
+      menuFrame->SelectMenu(false);
+
+    AutoHandlingUserInputStatePusher userInpStatePusher(mUserInput, nullptr,
+                                                        shell->GetDocument());
+    nsContentUtils::DispatchXULCommand(mMenu, mIsTrusted, nullptr, shell,
+                                       mControl, mAlt, mShift, mMeta);
+  }
+
+  if (popup && mCloseMenuMode != CloseMenuMode_None)
+    pm->HidePopup(popup, mCloseMenuMode == CloseMenuMode_Auto, true, false, false);
+
+  return NS_OK;
+}
diff --git a/layout/xul/nsXULPopupManager.h b/layout/xul/nsXULPopupManager.h
new file mode 100644
index 0000000000..41644d7e95
--- /dev/null
+++ b/layout/xul/nsXULPopupManager.h
@@ -0,0 +1,823 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * The XUL Popup Manager keeps track of all open popups.
+ */
+
+#ifndef nsXULPopupManager_h__
+#define nsXULPopupManager_h__
+
+#include "mozilla/Logging.h"
+#include "nsIContent.h"
+#include "nsIRollupListener.h"
+#include "nsIDOMEventListener.h"
+#include "nsPoint.h"
+#include "nsCOMPtr.h"
+#include "nsTArray.h"
+#include "nsIObserver.h"
+#include "nsITimer.h"
+#include "nsIReflowCallback.h"
+#include "nsThreadUtils.h"
+#include "nsStyleConsts.h"
+#include "nsWidgetInitData.h"
+#include "mozilla/Attributes.h"
+#include "Units.h"
+
+// X.h defines KeyPress
+#ifdef KeyPress
+#undef KeyPress
+#endif
+
+/**
+ * There are two types that are used:
+ *   - dismissable popups such as menus, which should close up when there is a
+ *     click outside the popup. In this situation, the entire chain of menus
+ *     above should also be closed.
+ *   - panels, which stay open until a request is made to close them. This
+ *     type is used by tooltips.
+ *
+ * When a new popup is opened, it is appended to the popup chain, stored in a
+ * linked list in mPopups for dismissable menus and panels or mNoHidePanels
+ * for tooltips and panels with noautohide="true".
+ * Popups are stored in this list linked from newest to oldest. When a click
+ * occurs outside one of the open dismissable popups, the chain is closed by
+ * calling Rollup.
+ */
+
+class nsContainerFrame;
+class nsMenuFrame;
+class nsMenuPopupFrame;
+class nsMenuBarFrame;
+class nsMenuParent;
+class nsIDOMKeyEvent;
+class nsIDocShellTreeItem;
+class nsPIDOMWindowOuter;
+
+// when a menu command is executed, the closemenu attribute may be used
+// to define how the menu should be closed up
+enum CloseMenuMode {
+  CloseMenuMode_Auto, // close up the chain of menus, default value
+  CloseMenuMode_None, // don't close up any menus
+  CloseMenuMode_Single // close up only the menu the command is inside
+};
+
+/**
+ * nsNavigationDirection: an enum expressing navigation through the menus in
+ * terms which are independent of the directionality of the chrome. The
+ * terminology, derived from XSL-FO and CSS3 (e.g. 
+ * http://www.w3.org/TR/css3-text/#TextLayout), is BASE (Before, After, Start,
+ * End), with the addition of First and Last (mapped to Home and End
+ * respectively).
+ *
+ * In languages such as English where the inline progression is left-to-right
+ * and the block progression is top-to-bottom (lr-tb), these terms will map out
+ * as in the following diagram
+ *
+ *  --- inline progression --->
+ *
+ *           First              |
+ *           ...                |
+ *           Before             |
+ *         +--------+         block
+ *   Start |        | End  progression
+ *         +--------+           |
+ *           After              |
+ *           ...                |
+ *           Last               V
+ * 
+ */
+
+enum nsNavigationDirection {
+  eNavigationDirection_Last,
+  eNavigationDirection_First,
+  eNavigationDirection_Start,
+  eNavigationDirection_Before,
+  eNavigationDirection_End,
+  eNavigationDirection_After
+};
+
+enum nsIgnoreKeys {
+  eIgnoreKeys_False,
+  eIgnoreKeys_True,
+  eIgnoreKeys_Shortcuts,
+};
+
+#define NS_DIRECTION_IS_INLINE(dir) (dir == eNavigationDirection_Start ||     \
+                                     dir == eNavigationDirection_End)
+#define NS_DIRECTION_IS_BLOCK(dir) (dir == eNavigationDirection_Before || \
+                                    dir == eNavigationDirection_After)
+#define NS_DIRECTION_IS_BLOCK_TO_EDGE(dir) (dir == eNavigationDirection_First ||    \
+                                            dir == eNavigationDirection_Last)
+
+static_assert(NS_STYLE_DIRECTION_LTR == 0 && NS_STYLE_DIRECTION_RTL == 1,
+              "Left to Right should be 0 and Right to Left should be 1");
+
+/**
+ * DirectionFromKeyCodeTable: two arrays, the first for left-to-right and the
+ * other for right-to-left, that map keycodes to values of
+ * nsNavigationDirection.
+ */
+extern const nsNavigationDirection DirectionFromKeyCodeTable[2][6];
+
+#define NS_DIRECTION_FROM_KEY_CODE(frame, keycode)                     \
+  (DirectionFromKeyCodeTable[frame->StyleVisibility()->mDirection]  \
+                            [keycode - nsIDOMKeyEvent::DOM_VK_END])
+
+// nsMenuChainItem holds info about an open popup. Items are stored in a
+// doubly linked list. Note that the linked list is stored beginning from
+// the lowest child in a chain of menus, as this is the active submenu.
+class nsMenuChainItem
+{
+private:
+  nsMenuPopupFrame* mFrame; // the popup frame
+  nsPopupType mPopupType; // the popup type of the frame
+  bool mIsContext; // true for context menus
+  bool mOnMenuBar; // true if the menu is on a menu bar
+  nsIgnoreKeys mIgnoreKeys; // indicates how keyboard listeners should be used
+
+  nsMenuChainItem* mParent;
+  nsMenuChainItem* mChild;
+
+public:
+  nsMenuChainItem(nsMenuPopupFrame* aFrame, bool aIsContext, nsPopupType aPopupType)
+    : mFrame(aFrame),
+      mPopupType(aPopupType),
+      mIsContext(aIsContext),
+      mOnMenuBar(false),
+      mIgnoreKeys(eIgnoreKeys_False),
+      mParent(nullptr),
+      mChild(nullptr)
+  {
+    NS_ASSERTION(aFrame, "null frame passed to nsMenuChainItem constructor");
+    MOZ_COUNT_CTOR(nsMenuChainItem);
+  }
+
+  ~nsMenuChainItem()
+  {
+    MOZ_COUNT_DTOR(nsMenuChainItem);
+  }
+
+  nsIContent* Content();
+  nsMenuPopupFrame* Frame() { return mFrame; }
+  nsPopupType PopupType() { return mPopupType; }
+  bool IsMenu() { return mPopupType == ePopupTypeMenu; }
+  bool IsContextMenu() { return mIsContext; }
+  nsIgnoreKeys IgnoreKeys() { return mIgnoreKeys; }
+  void SetIgnoreKeys(nsIgnoreKeys aIgnoreKeys) { mIgnoreKeys = aIgnoreKeys; }
+  bool IsOnMenuBar() { return mOnMenuBar; }
+  void SetOnMenuBar(bool aOnMenuBar) { mOnMenuBar = aOnMenuBar; }
+  nsMenuChainItem* GetParent() { return mParent; }
+  nsMenuChainItem* GetChild() { return mChild; }
+
+  // set the parent of this item to aParent, also changing the parent
+  // to have this as a child.
+  void SetParent(nsMenuChainItem* aParent);
+
+  // removes an item from the chain. The root pointer must be supplied in case
+  // the item is the first item in the chain in which case the pointer will be
+  // set to the next item, or null if there isn't another item. After detaching,
+  // this item will not have a parent or a child.
+  void Detach(nsMenuChainItem** aRoot);
+};
+
+// this class is used for dispatching popupshowing events asynchronously.
+class nsXULPopupShowingEvent : public mozilla::Runnable
+{
+public:
+  nsXULPopupShowingEvent(nsIContent *aPopup,
+                         bool aIsContextMenu,
+                         bool aSelectFirstItem)
+    : mPopup(aPopup),
+      mIsContextMenu(aIsContextMenu),
+      mSelectFirstItem(aSelectFirstItem)
+  {
+    NS_ASSERTION(aPopup, "null popup supplied to nsXULPopupShowingEvent constructor");
+  }
+
+  NS_IMETHOD Run() override;
+
+private:
+  nsCOMPtr<nsIContent> mPopup;
+  bool mIsContextMenu;
+  bool mSelectFirstItem;
+};
+
+// this class is used for dispatching popuphiding events asynchronously.
+class nsXULPopupHidingEvent : public mozilla::Runnable
+{
+public:
+  nsXULPopupHidingEvent(nsIContent *aPopup,
+                        nsIContent* aNextPopup,
+                        nsIContent* aLastPopup,
+                        nsPopupType aPopupType,
+                        bool aDeselectMenu,
+                        bool aIsCancel)
+    : mPopup(aPopup),
+      mNextPopup(aNextPopup),
+      mLastPopup(aLastPopup),
+      mPopupType(aPopupType),
+      mDeselectMenu(aDeselectMenu),
+      mIsRollup(aIsCancel)
+  {
+    NS_ASSERTION(aPopup, "null popup supplied to nsXULPopupHidingEvent constructor");
+    // aNextPopup and aLastPopup may be null
+  }
+
+  NS_IMETHOD Run() override;
+
+private:
+  nsCOMPtr<nsIContent> mPopup;
+  nsCOMPtr<nsIContent> mNextPopup;
+  nsCOMPtr<nsIContent> mLastPopup;
+  nsPopupType mPopupType;
+  bool mDeselectMenu;
+  bool mIsRollup;
+};
+
+// this class is used for dispatching popuppositioned events asynchronously.
+class nsXULPopupPositionedEvent : public mozilla::Runnable
+{
+public:
+  explicit nsXULPopupPositionedEvent(nsIContent *aPopup,
+                                     bool aIsContextMenu,
+                                     bool aSelectFirstItem)
+    : mPopup(aPopup)
+    , mIsContextMenu(aIsContextMenu)
+    , mSelectFirstItem(aSelectFirstItem)
+  {
+    NS_ASSERTION(aPopup, "null popup supplied to nsXULPopupShowingEvent constructor");
+  }
+
+  NS_IMETHOD Run() override;
+
+  // Asynchronously dispatch a popuppositioned event at aPopup if this is a
+  // panel that should receieve such events. Return true if the event was sent.
+  static bool DispatchIfNeeded(nsIContent *aPopup,
+                               bool aIsContextMenu,
+                               bool aSelectFirstItem);
+
+private:
+  nsCOMPtr<nsIContent> mPopup;
+  bool mIsContextMenu;
+  bool mSelectFirstItem;
+};
+
+// this class is used for dispatching menu command events asynchronously.
+class nsXULMenuCommandEvent : public mozilla::Runnable
+{
+public:
+  nsXULMenuCommandEvent(nsIContent *aMenu,
+                        bool aIsTrusted,
+                        bool aShift,
+                        bool aControl,
+                        bool aAlt,
+                        bool aMeta,
+                        bool aUserInput,
+                        bool aFlipChecked)
+    : mMenu(aMenu),
+      mIsTrusted(aIsTrusted),
+      mShift(aShift),
+      mControl(aControl),
+      mAlt(aAlt),
+      mMeta(aMeta),
+      mUserInput(aUserInput),
+      mFlipChecked(aFlipChecked),
+      mCloseMenuMode(CloseMenuMode_Auto)
+  {
+    NS_ASSERTION(aMenu, "null menu supplied to nsXULMenuCommandEvent constructor");
+  }
+
+  NS_IMETHOD Run() override;
+
+  void SetCloseMenuMode(CloseMenuMode aCloseMenuMode) { mCloseMenuMode = aCloseMenuMode; }
+
+private:
+  nsCOMPtr<nsIContent> mMenu;
+  bool mIsTrusted;
+  bool mShift;
+  bool mControl;
+  bool mAlt;
+  bool mMeta;
+  bool mUserInput;
+  bool mFlipChecked;
+  CloseMenuMode mCloseMenuMode;
+};
+
+class nsXULPopupManager final : public nsIDOMEventListener,
+                                public nsIRollupListener,
+                                public nsITimerCallback,
+                                public nsIObserver
+{
+
+public:
+  friend class nsXULPopupShowingEvent;
+  friend class nsXULPopupHidingEvent;
+  friend class nsXULPopupPositionedEvent;
+  friend class nsXULMenuCommandEvent;
+  friend class TransitionEnder;
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+  NS_DECL_NSITIMERCALLBACK
+  NS_DECL_NSIDOMEVENTLISTENER
+
+  // nsIRollupListener
+  virtual bool Rollup(uint32_t aCount, bool aFlush,
+                      const nsIntPoint* pos, nsIContent** aLastRolledUp) override;
+  virtual bool ShouldRollupOnMouseWheelEvent() override;
+  virtual bool ShouldConsumeOnMouseWheelEvent() override;
+  virtual bool ShouldRollupOnMouseActivate() override;
+  virtual uint32_t GetSubmenuWidgetChain(nsTArray<nsIWidget*> *aWidgetChain) override;
+  virtual void NotifyGeometryChange() override {}
+  virtual nsIWidget* GetRollupWidget() override;
+
+  static nsXULPopupManager* sInstance;
+
+  // initialize and shutdown methods called by nsLayoutStatics
+  static nsresult Init();
+  static void Shutdown();
+
+  // returns a weak reference to the popup manager instance, could return null
+  // if a popup manager could not be allocated
+  static nsXULPopupManager* GetInstance();
+
+  // This should be called when a window is moved or resized to adjust the
+  // popups accordingly.
+  void AdjustPopupsOnWindowChange(nsPIDOMWindowOuter* aWindow);
+  void AdjustPopupsOnWindowChange(nsIPresShell* aPresShell);
+
+  // given a menu frame, find the prevous or next menu frame. If aPopup is
+  // true then navigate a menupopup, from one item on the menu to the previous
+  // or next one. This is used for cursor navigation between items in a popup
+  // menu. If aIsPopup is false, the navigation is on a menubar, so navigate
+  // between menus on the menubar. This is used for left/right cursor navigation.
+  //
+  // Items that are not valid, such as non-menu or non-menuitem elements are
+  // skipped, and the next or previous item after that is checked.
+  //
+  // If aStart is null, the first valid item is retrieved by GetNextMenuItem
+  // and the last valid item is retrieved by GetPreviousMenuItem.
+  //
+  // Both methods will loop around the beginning or end if needed.
+  //
+  // aParent - the parent menubar or menupopup
+  // aStart - the menu/menuitem to start navigation from. GetPreviousMenuItem
+  //          returns the item before it, while GetNextMenuItem returns the
+  //          item after it.
+  // aIsPopup - true for menupopups, false for menubars
+  static nsMenuFrame* GetPreviousMenuItem(nsContainerFrame* aParent,
+                                          nsMenuFrame* aStart,
+                                          bool aIsPopup);
+  static nsMenuFrame* GetNextMenuItem(nsContainerFrame* aParent,
+                                      nsMenuFrame* aStart,
+                                      bool aIsPopup);
+
+  // returns true if the menu item aContent is a valid menuitem which may
+  // be navigated to. aIsPopup should be true for items on a popup, or false
+  // for items on a menubar.
+  static bool IsValidMenuItem(nsIContent* aContent, bool aOnPopup);
+
+  // inform the popup manager that a menu bar has been activated or deactivated,
+  // either because one of its menus has opened or closed, or that the menubar
+  // has been focused such that its menus may be navigated with the keyboard.
+  // aActivate should be true when the menubar should be focused, and false
+  // when the active menu bar should be defocused. In the latter case, if
+  // aMenuBar isn't currently active, yet another menu bar is, that menu bar
+  // will remain active.
+  void SetActiveMenuBar(nsMenuBarFrame* aMenuBar, bool aActivate);
+
+  // retrieve the node and offset of the last mouse event used to open a
+  // context menu. This information is determined from the rangeParent and
+  // the rangeOffset of the event supplied to ShowPopup or ShowPopupAtScreen.
+  // This is used by the implementation of nsIDOMXULDocument::GetPopupRangeParent
+  // and nsIDOMXULDocument::GetPopupRangeOffset.
+  void GetMouseLocation(nsIDOMNode** aNode, int32_t* aOffset);
+
+  /**
+   * Open a <menu> given its content node. If aSelectFirstItem is
+   * set to true, the first item on the menu will automatically be
+   * selected. If aAsynchronous is true, the event will be dispatched
+   * asynchronously. This should be true when called from frame code.
+   */
+  void ShowMenu(nsIContent *aMenu, bool aSelectFirstItem, bool aAsynchronous);
+
+  /**
+   * Open a popup, either anchored or unanchored. If aSelectFirstItem is
+   * true, then the first item in the menu is selected. The arguments are
+   * similar to those for nsIPopupBoxObject::OpenPopup.
+   *
+   * aTriggerEvent should be the event that triggered the event. This is used
+   * to determine the coordinates and trigger node for the popup. This may be
+   * null if the popup was not triggered by an event.
+   *
+   * This fires the popupshowing event synchronously.
+   */
+  void ShowPopup(nsIContent* aPopup,
+                 nsIContent* aAnchorContent,
+                 const nsAString& aPosition,
+                 int32_t aXPos, int32_t aYPos,
+                 bool aIsContextMenu,
+                 bool aAttributesOverride,
+                 bool aSelectFirstItem,
+                 nsIDOMEvent* aTriggerEvent);
+
+  /**
+   * Open a popup at a specific screen position specified by aXPos and aYPos,
+   * measured in CSS pixels.
+   *
+   * This fires the popupshowing event synchronously.
+   * 
+   * If aIsContextMenu is true, the popup is positioned at a slight
+   * offset from aXPos/aYPos to ensure that it is not under the mouse
+   * cursor.
+   */
+  void ShowPopupAtScreen(nsIContent* aPopup,
+                         int32_t aXPos, int32_t aYPos,
+                         bool aIsContextMenu,
+                         nsIDOMEvent* aTriggerEvent);
+
+  /* Open a popup anchored at a screen rectangle specified by aRect.
+   * The remaining arguments are similar to ShowPopup.
+   */
+  void ShowPopupAtScreenRect(nsIContent* aPopup,
+                             const nsAString& aPosition,
+                             const nsIntRect& aRect,
+                             bool aIsContextMenu,
+                             bool aAttributesOverride,
+                             nsIDOMEvent* aTriggerEvent);
+
+  /**
+   * Open a tooltip at a specific screen position specified by aXPos and aYPos,
+   * measured in CSS pixels.
+   *
+   * This fires the popupshowing event synchronously.
+   */
+  void ShowTooltipAtScreen(nsIContent* aPopup,
+                           nsIContent* aTriggerContent,
+                           int32_t aXPos, int32_t aYPos);
+
+  /**
+   * This method is provided only for compatibility with an older popup API.
+   * New code should not call this function and should call ShowPopup instead.
+   *
+   * This fires the popupshowing event synchronously.
+   */
+  void ShowPopupWithAnchorAlign(nsIContent* aPopup,
+                                nsIContent* aAnchorContent,
+                                nsAString& aAnchor,
+                                nsAString& aAlign,
+                                int32_t aXPos, int32_t aYPos,
+                                bool aIsContextMenu);
+
+  /*
+   * Hide a popup aPopup. If the popup is in a <menu>, then also inform the
+   * menu that the popup is being hidden.
+   *
+   * aHideChain - true if the entire chain of menus should be closed. If false,
+   *              only this popup is closed.
+   * aDeselectMenu - true if the parent <menu> of the popup should be deselected.
+   *                 This will be false when the menu is closed by pressing the
+   *                 Escape key.
+   * aAsynchronous - true if the first popuphiding event should be sent
+   *                 asynchrously. This should be true if HidePopup is called
+   *                 from a frame.
+   * aIsCancel - true if this popup is hiding due to being cancelled.
+   * aLastPopup - optional popup to close last when hiding a chain of menus.
+   *              If null, then all popups will be closed.
+   */
+  void HidePopup(nsIContent* aPopup,
+                 bool aHideChain,
+                 bool aDeselectMenu,
+                 bool aAsynchronous,
+                 bool aIsCancel,
+                 nsIContent* aLastPopup = nullptr);
+
+  /**
+   * Hide the popup aFrame. This method is called by the view manager when the
+   * close button is pressed.
+   */
+  void HidePopup(nsIFrame* aFrame);
+
+  /**
+   * Hide a popup after a short delay. This is used when rolling over menu items.
+   * This timer is stored in mCloseTimer. The timer may be cancelled and the popup
+   * closed by calling KillMenuTimer.
+   */
+  void HidePopupAfterDelay(nsMenuPopupFrame* aPopup);
+
+  /**
+   * Hide all of the popups from a given docshell. This should be called when the
+   * document is hidden.
+   */
+  void HidePopupsInDocShell(nsIDocShellTreeItem* aDocShellToHide);
+
+  /**
+   * Enable or disable the dynamic noautohide state of a panel.
+   *
+   * aPanel - the panel whose state is to change
+   * aShouldRollup - whether the panel is no longer noautohide
+   */
+  void EnableRollup(nsIContent* aPopup, bool aShouldRollup);
+
+  /**
+   * Execute a menu command from the triggering event aEvent.
+   *
+   * aMenu - a menuitem to execute
+   * aEvent - an nsXULMenuCommandEvent that contains all the info from the mouse
+   *          event which triggered the menu to be executed, may not be null
+   */
+  void ExecuteMenu(nsIContent* aMenu, nsXULMenuCommandEvent* aEvent);
+
+  /**
+   * Return true if the popup for the supplied content node is open.
+   */
+  bool IsPopupOpen(nsIContent* aPopup);
+
+  /**
+   * Return true if the popup for the supplied menu parent is open.
+   */
+  bool IsPopupOpenForMenuParent(nsMenuParent* aMenuParent);
+
+  /**
+   * Return the frame for the topmost open popup of a given type, or null if
+   * no popup of that type is open. If aType is ePopupTypeAny, a menu of any
+   * type is returned, except for popups in the mNoHidePanels list.
+   */
+  nsIFrame* GetTopPopup(nsPopupType aType);
+
+  /**
+   * Return an array of all the open and visible popup frames for
+   * menus, in order from top to bottom.
+   */
+  void GetVisiblePopups(nsTArray<nsIFrame *>& aPopups);
+
+  /**
+   * Get the node that last triggered a popup or tooltip in the document
+   * aDocument. aDocument must be non-null and be a document contained within
+   * the same window hierarchy as the popup to retrieve.
+   */
+  already_AddRefed<nsIDOMNode> GetLastTriggerPopupNode(nsIDocument* aDocument)
+  {
+    return GetLastTriggerNode(aDocument, false);
+  }
+
+  already_AddRefed<nsIDOMNode> GetLastTriggerTooltipNode(nsIDocument* aDocument)
+  {
+    return GetLastTriggerNode(aDocument, true);
+  }
+
+  /**
+   * Return false if a popup may not be opened. This will return false if the
+   * popup is already open, if the popup is in a content shell that is not
+   * focused, or if it is a submenu of another menu that isn't open.
+   */
+  bool MayShowPopup(nsMenuPopupFrame* aFrame);
+
+  /**
+   * Indicate that the popup associated with aView has been moved to the
+   * specified screen coordiates.
+   */
+  void PopupMoved(nsIFrame* aFrame, nsIntPoint aPoint);
+
+  /**
+   * Indicate that the popup associated with aView has been resized to the
+   * given device pixel size aSize.
+   */
+  void PopupResized(nsIFrame* aFrame, mozilla::LayoutDeviceIntSize aSize);
+
+  /**
+   * Called when a popup frame is destroyed. In this case, just remove the
+   * item and later popups from the list. No point going through HidePopup as
+   * the frames have gone away.
+   */
+  void PopupDestroyed(nsMenuPopupFrame* aFrame);
+
+  /**
+   * Returns true if there is a context menu open. If aPopup is specified,
+   * then the context menu must be later in the chain than aPopup. If aPopup
+   * is null, returns true if any context menu at all is open.
+   */
+  bool HasContextMenu(nsMenuPopupFrame* aPopup);
+
+  /**
+   * Update the commands for the menus within the menu popup for a given
+   * content node. aPopup should be a XUL menupopup element. This method
+   * changes attributes on the children of aPopup, and deals only with the
+   * content of the popup, not the frames.
+   */
+  void UpdateMenuItems(nsIContent* aPopup);
+
+  /**
+   * Stop the timer which hides a popup after a delay, started by a previous
+   * call to HidePopupAfterDelay. In addition, the popup awaiting to be hidden
+   * is closed asynchronously.
+   */
+  void KillMenuTimer();
+
+  /**
+   * Cancel the timer which closes menus after delay, but only if the menu to
+   * close is aMenuParent. When a submenu is opened, the user might move the
+   * mouse over a sibling menuitem which would normally close the menu. This
+   * menu is closed via a timer. However, if the user moves the mouse over the
+   * submenu before the timer fires, we should instead cancel the timer. This
+   * ensures that the user can move the mouse diagonally over a menu.
+   */
+  void CancelMenuTimer(nsMenuParent* aMenuParent);
+
+  /**
+   * Handles navigation for menu accelkeys. If aFrame is specified, then the
+   * key is handled by that popup, otherwise if aFrame is null, the key is
+   * handled by the active popup or menubar.
+   */
+  bool HandleShortcutNavigation(nsIDOMKeyEvent* aKeyEvent,
+                                nsMenuPopupFrame* aFrame);
+
+  /**
+   * Handles cursor navigation within a menu. Returns true if the key has
+   * been handled.
+   */
+  bool HandleKeyboardNavigation(uint32_t aKeyCode);
+
+  /**
+   * Handle keyboard navigation within a menu popup specified by aFrame.
+   * Returns true if the key was handled and other default handling
+   * should not occur.
+   */
+  bool HandleKeyboardNavigationInPopup(nsMenuPopupFrame* aFrame,
+                                         nsNavigationDirection aDir)
+  {
+    return HandleKeyboardNavigationInPopup(nullptr, aFrame, aDir);
+  }
+
+  /**
+   * Handles the keyboard event with keyCode value. Returns true if the event
+   * has been handled.
+   */
+  bool HandleKeyboardEventWithKeyCode(nsIDOMKeyEvent* aKeyEvent,
+                                      nsMenuChainItem* aTopVisibleMenuItem);
+
+  nsresult KeyUp(nsIDOMKeyEvent* aKeyEvent);
+  nsresult KeyDown(nsIDOMKeyEvent* aKeyEvent);
+  nsresult KeyPress(nsIDOMKeyEvent* aKeyEvent);
+
+protected:
+  nsXULPopupManager();
+  ~nsXULPopupManager();
+
+  // get the nsMenuPopupFrame, if any, for the given content node
+  nsMenuPopupFrame* GetPopupFrameForContent(nsIContent* aContent, bool aShouldFlush);
+
+  // return the topmost menu, skipping over invisible popups
+  nsMenuChainItem* GetTopVisibleMenu();
+
+  // Hide all of the visible popups from the given list. This function can
+  // cause style changes and frame destruction.
+  void HidePopupsInList(const nsTArray<nsMenuPopupFrame *> &aFrames);
+
+  // set the event that was used to trigger the popup, or null to clear the
+  // event details. aTriggerContent will be set to the target of the event.
+  void InitTriggerEvent(nsIDOMEvent* aEvent, nsIContent* aPopup, nsIContent** aTriggerContent);
+
+  // callbacks for ShowPopup and HidePopup as events may be done asynchronously
+  void ShowPopupCallback(nsIContent* aPopup,
+                         nsMenuPopupFrame* aPopupFrame,
+                         bool aIsContextMenu,
+                         bool aSelectFirstItem);
+  void HidePopupCallback(nsIContent* aPopup,
+                         nsMenuPopupFrame* aPopupFrame,
+                         nsIContent* aNextPopup,
+                         nsIContent* aLastPopup,
+                         nsPopupType aPopupType,
+                         bool aDeselectMenu);
+
+  /**
+   * Fire a popupshowing event on the popup and then open the popup.
+   *
+   * aPopup - the popup to open
+   * aIsContextMenu - true for context menus
+   * aSelectFirstItem - true to select the first item in the menu
+   */
+  void FirePopupShowingEvent(nsIContent* aPopup,
+                             bool aIsContextMenu,
+                             bool aSelectFirstItem);
+
+  /**
+   * Fire a popuphiding event and then hide the popup. This will be called
+   * recursively if aNextPopup and aLastPopup are set in order to hide a chain
+   * of open menus. If these are not set, only one popup is closed. However,
+   * if the popup type indicates a menu, yet the next popup is not a menu,
+   * then this ends the closing of popups. This allows a menulist inside a
+   * non-menu to close up the menu but not close up the panel it is contained
+   * within.
+   *
+   * The caller must keep a strong reference to aPopup, aNextPopup and aLastPopup.
+   *
+   * aPopup - the popup to hide
+   * aNextPopup - the next popup to hide
+   * aLastPopup - the last popup in the chain to hide
+   * aPresContext - nsPresContext for the popup's frame
+   * aPopupType - the PopupType of the frame. 
+   * aDeselectMenu - true to unhighlight the menu when hiding it
+   * aIsCancel - true if this popup is hiding due to being cancelled.
+   */
+  void FirePopupHidingEvent(nsIContent* aPopup,
+                            nsIContent* aNextPopup,
+                            nsIContent* aLastPopup,
+                            nsPresContext *aPresContext,
+                            nsPopupType aPopupType,
+                            bool aDeselectMenu,
+                            bool aIsCancel);
+
+  /**
+   * Handle keyboard navigation within a menu popup specified by aItem.
+   */
+  bool HandleKeyboardNavigationInPopup(nsMenuChainItem* aItem,
+                                         nsNavigationDirection aDir)
+  {
+    return HandleKeyboardNavigationInPopup(aItem, aItem->Frame(), aDir);
+  }
+
+private:
+  /**
+   * Handle keyboard navigation within a menu popup aFrame. If aItem is
+   * supplied, then it is expected to have a frame equal to aFrame.
+   * If aItem is non-null, then the navigation may be redirected to
+   * an open submenu if one exists. Returns true if the key was
+   * handled and other default handling should not occur.
+   */
+  bool HandleKeyboardNavigationInPopup(nsMenuChainItem* aItem,
+                                         nsMenuPopupFrame* aFrame,
+                                         nsNavigationDirection aDir);
+
+protected:
+
+  already_AddRefed<nsIDOMNode> GetLastTriggerNode(nsIDocument* aDocument, bool aIsTooltip);
+
+  /**
+   * Set mouse capturing for the current popup. This traps mouse clicks that
+   * occur outside the popup so that it can be closed up. aOldPopup should be
+   * set to the popup that was previously the current popup.
+   */
+  void SetCaptureState(nsIContent *aOldPopup);
+
+  /**
+   * Key event listeners are attached to the document containing the current
+   * menu for menu and shortcut navigation. Only one listener is needed at a
+   * time, stored in mKeyListener, so switch it only if the document changes.
+   * Having menus in different documents is very rare, so the listeners will
+   * usually only be attached when the first menu opens and removed when all
+   * menus have closed.
+   *
+   * This is also used when only a menubar is active without any open menus,
+   * so that keyboard navigation between menus on the menubar may be done.
+   */
+  void UpdateKeyboardListeners();
+
+  /*
+   * Returns true if the docshell for aDoc is aExpected or a child of aExpected.
+   */
+  bool IsChildOfDocShell(nsIDocument* aDoc, nsIDocShellTreeItem* aExpected);
+
+  // the document the key event listener is attached to
+  nsCOMPtr<mozilla::dom::EventTarget> mKeyListener;
+
+  // widget that is currently listening to rollup events
+  nsCOMPtr<nsIWidget> mWidget;
+
+  // range parent and offset set in SetTriggerEvent
+  nsCOMPtr<nsIDOMNode> mRangeParent;
+  int32_t mRangeOffset;
+  // Device pixels relative to the showing popup's presshell's
+  // root prescontext's root frame.
+  mozilla::LayoutDeviceIntPoint mCachedMousePoint;
+
+  // cached modifiers
+  mozilla::Modifiers mCachedModifiers;
+
+  // set to the currently active menu bar, if any
+  nsMenuBarFrame* mActiveMenuBar;
+
+  // linked list of normal menus and panels.
+  nsMenuChainItem* mPopups;
+
+  // linked list of noautohide panels and tooltips.
+  nsMenuChainItem* mNoHidePanels;
+
+  // timer used for HidePopupAfterDelay
+  nsCOMPtr<nsITimer> mCloseTimer;
+
+  // a popup that is waiting on the timer
+  nsMenuPopupFrame* mTimerMenu;
+
+  // the popup that is currently being opened, stored only during the
+  // popupshowing event
+  nsCOMPtr<nsIContent> mOpeningPopup;
+
+  // If true, all popups won't hide automatically on blur
+  static bool sDevtoolsDisableAutoHide;
+};
+
+#endif
diff --git a/layout/xul/nsXULTooltipListener.cpp b/layout/xul/nsXULTooltipListener.cpp
new file mode 100644
index 0000000000..110f8c0e09
--- /dev/null
+++ b/layout/xul/nsXULTooltipListener.cpp
@@ -0,0 +1,729 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsXULTooltipListener.h"
+
+#include "nsIDOMMouseEvent.h"
+#include "nsIDOMXULDocument.h"
+#include "nsIDOMXULElement.h"
+#include "nsIDocument.h"
+#include "nsGkAtoms.h"
+#include "nsMenuPopupFrame.h"
+#include "nsIServiceManager.h"
+#include "nsIDragService.h"
+#include "nsIDragSession.h"
+#ifdef MOZ_XUL
+#include "nsITreeView.h"
+#endif
+#include "nsIScriptContext.h"
+#include "nsPIDOMWindow.h"
+#ifdef MOZ_XUL
+#include "nsXULPopupManager.h"
+#endif
+#include "nsIRootBox.h"
+#include "nsIBoxObject.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h" // for nsIDOMEvent::InternalDOMEvent()
+#include "mozilla/dom/BoxObject.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+nsXULTooltipListener* nsXULTooltipListener::mInstance = nullptr;
+
+//////////////////////////////////////////////////////////////////////////
+//// nsISupports
+
+nsXULTooltipListener::nsXULTooltipListener()
+  : mMouseScreenX(0)
+  , mMouseScreenY(0)
+  , mTooltipShownOnce(false)
+#ifdef MOZ_XUL
+  , mIsSourceTree(false)
+  , mNeedTitletip(false)
+  , mLastTreeRow(-1)
+#endif
+{
+  if (sTooltipListenerCount++ == 0) {
+    // register the callback so we get notified of updates
+    Preferences::RegisterCallback(ToolbarTipsPrefChanged,
+                                  "browser.chrome.toolbar_tips");
+
+    // Call the pref callback to initialize our state.
+    ToolbarTipsPrefChanged("browser.chrome.toolbar_tips", nullptr);
+  }
+}
+
+nsXULTooltipListener::~nsXULTooltipListener()
+{
+  if (nsXULTooltipListener::mInstance == this) {
+    ClearTooltipCache();
+  }
+  HideTooltip();
+
+  if (--sTooltipListenerCount == 0) {
+    // Unregister our pref observer
+    Preferences::UnregisterCallback(ToolbarTipsPrefChanged,
+                                    "browser.chrome.toolbar_tips");
+  }
+}
+
+NS_IMPL_ISUPPORTS(nsXULTooltipListener, nsIDOMEventListener)
+
+void
+nsXULTooltipListener::MouseOut(nsIDOMEvent* aEvent)
+{
+  // reset flag so that tooltip will display on the next MouseMove
+  mTooltipShownOnce = false;
+
+  // if the timer is running and no tooltip is shown, we
+  // have to cancel the timer here so that it doesn't 
+  // show the tooltip if we move the mouse out of the window
+  nsCOMPtr<nsIContent> currentTooltip = do_QueryReferent(mCurrentTooltip);
+  if (mTooltipTimer && !currentTooltip) {
+    mTooltipTimer->Cancel();
+    mTooltipTimer = nullptr;
+    return;
+  }
+
+#ifdef DEBUG_crap
+  if (mNeedTitletip)
+    return;
+#endif
+
+#ifdef MOZ_XUL
+  // check to see if the mouse left the targetNode, and if so,
+  // hide the tooltip
+  if (currentTooltip) {
+    // which node did the mouse leave?
+    nsCOMPtr<nsIDOMNode> targetNode = do_QueryInterface(
+      aEvent->InternalDOMEvent()->GetTarget());
+
+    nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+    if (pm) {
+      nsCOMPtr<nsIDOMNode> tooltipNode =
+        pm->GetLastTriggerTooltipNode(currentTooltip->GetUncomposedDoc());
+      if (tooltipNode == targetNode) {
+        // if the target node is the current tooltip target node, the mouse
+        // left the node the tooltip appeared on, so close the tooltip.
+        HideTooltip();
+        // reset special tree tracking
+        if (mIsSourceTree) {
+          mLastTreeRow = -1;
+          mLastTreeCol = nullptr;
+        }
+      }
+    }
+  }
+#endif
+}
+
+void
+nsXULTooltipListener::MouseMove(nsIDOMEvent* aEvent)
+{
+  if (!sShowTooltips)
+    return;
+
+  // stash the coordinates of the event so that we can still get back to it from within the 
+  // timer callback. On win32, we'll get a MouseMove event even when a popup goes away --
+  // even when the mouse doesn't change position! To get around this, we make sure the
+  // mouse has really moved before proceeding.
+  nsCOMPtr<nsIDOMMouseEvent> mouseEvent(do_QueryInterface(aEvent));
+  if (!mouseEvent)
+    return;
+  int32_t newMouseX, newMouseY;
+  mouseEvent->GetScreenX(&newMouseX);
+  mouseEvent->GetScreenY(&newMouseY);
+
+  // filter out false win32 MouseMove event
+  if (mMouseScreenX == newMouseX && mMouseScreenY == newMouseY)
+    return;
+
+  // filter out minor movements due to crappy optical mice and shaky hands
+  // to prevent tooltips from hiding prematurely.
+  nsCOMPtr<nsIContent> currentTooltip = do_QueryReferent(mCurrentTooltip);
+
+  if ((currentTooltip) &&
+      (abs(mMouseScreenX - newMouseX) <= kTooltipMouseMoveTolerance) &&
+      (abs(mMouseScreenY - newMouseY) <= kTooltipMouseMoveTolerance))
+    return;
+  mMouseScreenX = newMouseX;
+  mMouseScreenY = newMouseY;
+
+  nsCOMPtr<nsIContent> sourceContent = do_QueryInterface(
+    aEvent->InternalDOMEvent()->GetCurrentTarget());
+  mSourceNode = do_GetWeakReference(sourceContent);
+#ifdef MOZ_XUL
+  mIsSourceTree = sourceContent->IsXULElement(nsGkAtoms::treechildren);
+  if (mIsSourceTree)
+    CheckTreeBodyMove(mouseEvent);
+#endif
+
+  // as the mouse moves, we want to make sure we reset the timer to show it, 
+  // so that the delay is from when the mouse stops moving, not when it enters
+  // the node.
+  KillTooltipTimer();
+
+  // If the mouse moves while the tooltip is up, hide it. If nothing is
+  // showing and the tooltip hasn't been displayed since the mouse entered
+  // the node, then start the timer to show the tooltip.
+  if (!currentTooltip && !mTooltipShownOnce) {
+    nsCOMPtr<EventTarget> eventTarget = aEvent->InternalDOMEvent()->GetTarget();
+
+    // don't show tooltips attached to elements outside of a menu popup
+    // when hovering over an element inside it. The popupsinherittooltip
+    // attribute may be used to disable this behaviour, which is useful for
+    // large menu hierarchies such as bookmarks.
+    if (!sourceContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::popupsinherittooltip,
+                                    nsGkAtoms::_true, eCaseMatters)) {
+      nsCOMPtr<nsIContent> targetContent = do_QueryInterface(eventTarget);
+      while (targetContent && targetContent != sourceContent) {
+        if (targetContent->IsAnyOfXULElements(nsGkAtoms::menupopup,
+                                              nsGkAtoms::panel,
+                                              nsGkAtoms::tooltip)) {
+          mSourceNode = nullptr;
+          return;
+        }
+
+        targetContent = targetContent->GetParent();
+      }
+    }
+
+    mTooltipTimer = do_CreateInstance("@mozilla.org/timer;1");
+    if (mTooltipTimer) {
+      mTargetNode = do_GetWeakReference(eventTarget);
+      if (mTargetNode) {
+        nsresult rv =
+          mTooltipTimer->InitWithFuncCallback(sTooltipCallback, this,
+            LookAndFeel::GetInt(LookAndFeel::eIntID_TooltipDelay, 500),
+            nsITimer::TYPE_ONE_SHOT);
+        if (NS_FAILED(rv)) {
+          mTargetNode = nullptr;
+          mSourceNode = nullptr;
+        }
+      }
+    }
+    return;
+  }
+
+#ifdef MOZ_XUL
+  if (mIsSourceTree)
+    return;
+#endif
+
+  HideTooltip();
+  // set a flag so that the tooltip is only displayed once until the mouse
+  // leaves the node
+  mTooltipShownOnce = true;
+}
+
+NS_IMETHODIMP
+nsXULTooltipListener::HandleEvent(nsIDOMEvent* aEvent)
+{
+  nsAutoString type;
+  aEvent->GetType(type);
+  if (type.EqualsLiteral("DOMMouseScroll") ||
+      type.EqualsLiteral("keydown") ||
+      type.EqualsLiteral("mousedown") ||
+      type.EqualsLiteral("mouseup") ||
+      type.EqualsLiteral("dragstart")) {
+    HideTooltip();
+    return NS_OK;
+  }
+
+  if (type.EqualsLiteral("popuphiding")) {
+    DestroyTooltip();
+    return NS_OK;
+  }
+
+  // Note that mousemove, mouseover and mouseout might be
+  // fired even during dragging due to widget's bug.
+  nsCOMPtr<nsIDragService> dragService =
+    do_GetService("@mozilla.org/widget/dragservice;1");
+  NS_ENSURE_TRUE(dragService, NS_OK);
+  nsCOMPtr<nsIDragSession> dragSession;
+  dragService->GetCurrentSession(getter_AddRefs(dragSession));
+  if (dragSession) {
+    return NS_OK;
+  }
+
+  // Not dragging.
+
+  if (type.EqualsLiteral("mousemove")) {
+    MouseMove(aEvent);
+    return NS_OK;
+  }
+
+  if (type.EqualsLiteral("mouseout")) {
+    MouseOut(aEvent);
+    return NS_OK;
+  }
+
+  return NS_OK;
+}
+
+//////////////////////////////////////////////////////////////////////////
+//// nsXULTooltipListener
+
+// static
+void
+nsXULTooltipListener::ToolbarTipsPrefChanged(const char *aPref,
+                                             void *aClosure)
+{
+  sShowTooltips =
+    Preferences::GetBool("browser.chrome.toolbar_tips", sShowTooltips);
+}
+
+//////////////////////////////////////////////////////////////////////////
+//// nsXULTooltipListener
+
+bool nsXULTooltipListener::sShowTooltips = false;
+uint32_t nsXULTooltipListener::sTooltipListenerCount = 0;
+
+nsresult
+nsXULTooltipListener::AddTooltipSupport(nsIContent* aNode)
+{
+  if (!aNode)
+    return NS_ERROR_NULL_POINTER;
+
+  aNode->AddSystemEventListener(NS_LITERAL_STRING("mouseout"), this,
+                                false, false);
+  aNode->AddSystemEventListener(NS_LITERAL_STRING("mousemove"), this,
+                                false, false);
+  aNode->AddSystemEventListener(NS_LITERAL_STRING("mousedown"), this,
+                                false, false);
+  aNode->AddSystemEventListener(NS_LITERAL_STRING("mouseup"), this,
+                                false, false);
+  aNode->AddSystemEventListener(NS_LITERAL_STRING("dragstart"), this,
+                                true, false);
+
+  return NS_OK;
+}
+
+nsresult
+nsXULTooltipListener::RemoveTooltipSupport(nsIContent* aNode)
+{
+  if (!aNode)
+    return NS_ERROR_NULL_POINTER;
+
+  aNode->RemoveSystemEventListener(NS_LITERAL_STRING("mouseout"), this, false);
+  aNode->RemoveSystemEventListener(NS_LITERAL_STRING("mousemove"), this, false);
+  aNode->RemoveSystemEventListener(NS_LITERAL_STRING("mousedown"), this, false);
+  aNode->RemoveSystemEventListener(NS_LITERAL_STRING("mouseup"), this, false);
+  aNode->RemoveSystemEventListener(NS_LITERAL_STRING("dragstart"), this, true);
+
+  return NS_OK;
+}
+
+#ifdef MOZ_XUL
+void
+nsXULTooltipListener::CheckTreeBodyMove(nsIDOMMouseEvent* aMouseEvent)
+{
+  nsCOMPtr<nsIContent> sourceNode = do_QueryReferent(mSourceNode);
+  if (!sourceNode)
+    return;
+
+  // get the boxObject of the documentElement of the document the tree is in
+  nsCOMPtr<nsIBoxObject> bx;
+  nsIDocument* doc = sourceNode->GetComposedDoc();
+  if (doc) {
+    ErrorResult ignored;
+    bx = doc->GetBoxObjectFor(doc->GetRootElement(), ignored);
+  }
+
+  nsCOMPtr<nsITreeBoxObject> obx;
+  GetSourceTreeBoxObject(getter_AddRefs(obx));
+  if (bx && obx) {
+    int32_t x, y;
+    aMouseEvent->GetScreenX(&x);
+    aMouseEvent->GetScreenY(&y);
+
+    int32_t row;
+    nsCOMPtr<nsITreeColumn> col;
+    nsAutoString obj;
+
+    // subtract off the documentElement's boxObject
+    int32_t boxX, boxY;
+    bx->GetScreenX(&boxX);
+    bx->GetScreenY(&boxY);
+    x -= boxX;
+    y -= boxY;
+
+    obx->GetCellAt(x, y, &row, getter_AddRefs(col), obj);
+
+    // determine if we are going to need a titletip
+    // XXX check the disabletitletips attribute on the tree content
+    mNeedTitletip = false;
+    int16_t colType = -1;
+    if (col) {
+      col->GetType(&colType);
+    }
+    if (row >= 0 && obj.EqualsLiteral("text") &&
+        colType != nsITreeColumn::TYPE_PASSWORD) {
+      obx->IsCellCropped(row, col, &mNeedTitletip);
+    }
+
+    nsCOMPtr<nsIContent> currentTooltip = do_QueryReferent(mCurrentTooltip);
+    if (currentTooltip && (row != mLastTreeRow || col != mLastTreeCol)) {
+      HideTooltip();
+    } 
+
+    mLastTreeRow = row;
+    mLastTreeCol = col;
+  }
+}
+#endif
+
+nsresult
+nsXULTooltipListener::ShowTooltip()
+{
+  nsCOMPtr<nsIContent> sourceNode = do_QueryReferent(mSourceNode);
+
+  // get the tooltip content designated for the target node
+  nsCOMPtr<nsIContent> tooltipNode;
+  GetTooltipFor(sourceNode, getter_AddRefs(tooltipNode));
+  if (!tooltipNode || sourceNode == tooltipNode)
+    return NS_ERROR_FAILURE; // the target node doesn't need a tooltip
+
+  // set the node in the document that triggered the tooltip and show it
+  nsCOMPtr<nsIDOMXULDocument> xulDoc =
+    do_QueryInterface(tooltipNode->GetComposedDoc());
+  if (xulDoc) {
+    // Make sure the target node is still attached to some document. 
+    // It might have been deleted.
+    if (sourceNode->IsInComposedDoc()) {
+#ifdef MOZ_XUL
+      if (!mIsSourceTree) {
+        mLastTreeRow = -1;
+        mLastTreeCol = nullptr;
+      }
+#endif
+
+      mCurrentTooltip = do_GetWeakReference(tooltipNode);
+      LaunchTooltip();
+      mTargetNode = nullptr;
+
+      nsCOMPtr<nsIContent> currentTooltip = do_QueryReferent(mCurrentTooltip);
+      if (!currentTooltip)
+        return NS_OK;
+
+      // listen for popuphidden on the tooltip node, so that we can
+      // be sure DestroyPopup is called even if someone else closes the tooltip
+      currentTooltip->AddSystemEventListener(NS_LITERAL_STRING("popuphiding"), 
+                                             this, false, false);
+
+      // listen for mousedown, mouseup, keydown, and DOMMouseScroll events at document level
+      nsIDocument* doc = sourceNode->GetComposedDoc();
+      if (doc) {
+        // Probably, we should listen to untrusted events for hiding tooltips
+        // on content since tooltips might disturb something of web
+        // applications.  If we don't specify the aWantsUntrusted of
+        // AddSystemEventListener(), the event target sets it to TRUE if the
+        // target is in content.
+        doc->AddSystemEventListener(NS_LITERAL_STRING("DOMMouseScroll"),
+                                    this, true);
+        doc->AddSystemEventListener(NS_LITERAL_STRING("mousedown"),
+                                    this, true);
+        doc->AddSystemEventListener(NS_LITERAL_STRING("mouseup"),
+                                    this, true);
+        doc->AddSystemEventListener(NS_LITERAL_STRING("keydown"),
+                                    this, true);
+      }
+      mSourceNode = nullptr;
+    }
+  }
+
+  return NS_OK;
+}
+
+#ifdef MOZ_XUL
+// XXX: "This stuff inside DEBUG_crap could be used to make tree tooltips work
+//       in the future."
+#ifdef DEBUG_crap
+static void
+GetTreeCellCoords(nsITreeBoxObject* aTreeBox, nsIContent* aSourceNode, 
+                  int32_t aRow, nsITreeColumn* aCol, int32_t* aX, int32_t* aY)
+{
+  int32_t junk;
+  aTreeBox->GetCoordsForCellItem(aRow, aCol, EmptyCString(), aX, aY, &junk, &junk);
+  nsCOMPtr<nsIDOMXULElement> xulEl(do_QueryInterface(aSourceNode));
+  nsCOMPtr<nsIBoxObject> bx;
+  xulEl->GetBoxObject(getter_AddRefs(bx));
+  int32_t myX, myY;
+  bx->GetX(&myX);
+  bx->GetY(&myY);
+  *aX += myX;
+  *aY += myY;
+}
+#endif
+
+static void
+SetTitletipLabel(nsITreeBoxObject* aTreeBox, nsIContent* aTooltip,
+                 int32_t aRow, nsITreeColumn* aCol)
+{
+  nsCOMPtr<nsITreeView> view;
+  aTreeBox->GetView(getter_AddRefs(view));
+  if (view) {
+    nsAutoString label;
+#ifdef DEBUG
+    nsresult rv = 
+#endif
+      view->GetCellText(aRow, aCol, label);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Couldn't get the cell text!");
+    aTooltip->SetAttr(kNameSpaceID_None, nsGkAtoms::label, label, true);
+  }
+}
+#endif
+
+void
+nsXULTooltipListener::LaunchTooltip()
+{
+  nsCOMPtr<nsIContent> currentTooltip = do_QueryReferent(mCurrentTooltip);
+  if (!currentTooltip)
+    return;
+
+#ifdef MOZ_XUL
+  if (mIsSourceTree && mNeedTitletip) {
+    nsCOMPtr<nsITreeBoxObject> obx;
+    GetSourceTreeBoxObject(getter_AddRefs(obx));
+
+    SetTitletipLabel(obx, currentTooltip, mLastTreeRow, mLastTreeCol);
+    if (!(currentTooltip = do_QueryReferent(mCurrentTooltip))) {
+      // Because of mutation events, currentTooltip can be null.
+      return;
+    }
+    currentTooltip->SetAttr(kNameSpaceID_None, nsGkAtoms::titletip, NS_LITERAL_STRING("true"), true);
+  } else {
+    currentTooltip->UnsetAttr(kNameSpaceID_None, nsGkAtoms::titletip, true);
+  }
+  if (!(currentTooltip = do_QueryReferent(mCurrentTooltip))) {
+    // Because of mutation events, currentTooltip can be null.
+    return;
+  }
+
+  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+  if (pm) {
+    nsCOMPtr<nsIContent> target = do_QueryReferent(mTargetNode);
+    pm->ShowTooltipAtScreen(currentTooltip, target, mMouseScreenX, mMouseScreenY);
+
+    // Clear the current tooltip if the popup was not opened successfully.
+    if (!pm->IsPopupOpen(currentTooltip))
+      mCurrentTooltip = nullptr;
+  }
+#endif
+
+}
+
+nsresult
+nsXULTooltipListener::HideTooltip()
+{
+#ifdef MOZ_XUL
+  nsCOMPtr<nsIContent> currentTooltip = do_QueryReferent(mCurrentTooltip);
+  if (currentTooltip) {
+    nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
+    if (pm)
+      pm->HidePopup(currentTooltip, false, false, false, false);
+  }
+#endif
+
+  DestroyTooltip();
+  return NS_OK;
+}
+
+static void
+GetImmediateChild(nsIContent* aContent, nsIAtom *aTag, nsIContent** aResult) 
+{
+  *aResult = nullptr;
+  uint32_t childCount = aContent->GetChildCount();
+  for (uint32_t i = 0; i < childCount; i++) {
+    nsIContent *child = aContent->GetChildAt(i);
+
+    if (child->IsXULElement(aTag)) {
+      *aResult = child;
+      NS_ADDREF(*aResult);
+      return;
+    }
+  }
+
+  return;
+}
+
+nsresult
+nsXULTooltipListener::FindTooltip(nsIContent* aTarget, nsIContent** aTooltip)
+{
+  if (!aTarget)
+    return NS_ERROR_NULL_POINTER;
+
+  // before we go on, make sure that target node still has a window
+  nsIDocument *document = aTarget->GetComposedDoc();
+  if (!document) {
+    NS_WARNING("Unable to retrieve the tooltip node document.");
+    return NS_ERROR_FAILURE;
+  }
+  nsPIDOMWindowOuter *window = document->GetWindow();
+  if (!window) {
+    return NS_OK;
+  }
+
+  if (window->Closed()) {
+    return NS_OK;
+  }
+
+  nsAutoString tooltipText;
+  aTarget->GetAttr(kNameSpaceID_None, nsGkAtoms::tooltiptext, tooltipText);
+  if (!tooltipText.IsEmpty()) {
+    // specifying tooltiptext means we will always use the default tooltip
+    nsIRootBox* rootBox = nsIRootBox::GetRootBox(document->GetShell());
+    NS_ENSURE_STATE(rootBox);
+    *aTooltip = rootBox->GetDefaultTooltip();
+    if (*aTooltip) {
+      NS_ADDREF(*aTooltip);
+      (*aTooltip)->SetAttr(kNameSpaceID_None, nsGkAtoms::label, tooltipText, true);
+    }
+    return NS_OK;
+  }
+
+  nsAutoString tooltipId;
+  aTarget->GetAttr(kNameSpaceID_None, nsGkAtoms::tooltip, tooltipId);
+
+  // if tooltip == _child, look for first <tooltip> child
+  if (tooltipId.EqualsLiteral("_child")) {
+    GetImmediateChild(aTarget, nsGkAtoms::tooltip, aTooltip);
+    return NS_OK;
+  }
+
+  if (!tooltipId.IsEmpty() && aTarget->IsInUncomposedDoc()) {
+    // tooltip must be an id, use getElementById to find it
+    //XXXsmaug If aTarget is in shadow dom, should we use
+    //         ShadowRoot::GetElementById()?
+    nsCOMPtr<nsIContent> tooltipEl = document->GetElementById(tooltipId);
+
+    if (tooltipEl) {
+#ifdef MOZ_XUL
+      mNeedTitletip = false;
+#endif
+      tooltipEl.forget(aTooltip);
+      return NS_OK;
+    }
+  }
+
+#ifdef MOZ_XUL
+  // titletips should just use the default tooltip
+  if (mIsSourceTree && mNeedTitletip) {
+    nsIRootBox* rootBox = nsIRootBox::GetRootBox(document->GetShell());
+    NS_ENSURE_STATE(rootBox);
+    NS_IF_ADDREF(*aTooltip = rootBox->GetDefaultTooltip());
+  }
+#endif
+
+  return NS_OK;
+}
+
+
+nsresult
+nsXULTooltipListener::GetTooltipFor(nsIContent* aTarget, nsIContent** aTooltip)
+{
+  *aTooltip = nullptr;
+  nsCOMPtr<nsIContent> tooltip;
+  nsresult rv = FindTooltip(aTarget, getter_AddRefs(tooltip));
+  if (NS_FAILED(rv) || !tooltip) {
+    return rv;
+  }
+
+#ifdef MOZ_XUL
+  // Submenus can't be used as tooltips, see bug 288763.
+  nsIContent* parent = tooltip->GetParent();
+  if (parent) {
+    nsMenuFrame* menu = do_QueryFrame(parent->GetPrimaryFrame());
+    if (menu) {
+      NS_WARNING("Menu cannot be used as a tooltip");
+      return NS_ERROR_FAILURE;
+    }
+  }
+#endif
+
+  tooltip.swap(*aTooltip);
+  return rv;
+}
+
+nsresult
+nsXULTooltipListener::DestroyTooltip()
+{
+  nsCOMPtr<nsIDOMEventListener> kungFuDeathGrip(this);
+  nsCOMPtr<nsIContent> currentTooltip = do_QueryReferent(mCurrentTooltip);
+  if (currentTooltip) {
+    // release tooltip before removing listener to prevent our destructor from
+    // being called recursively (bug 120863)
+    mCurrentTooltip = nullptr;
+
+    // clear out the tooltip node on the document
+    nsCOMPtr<nsIDocument> doc = currentTooltip->GetComposedDoc();
+    if (doc) {
+      // remove the mousedown and keydown listener from document
+      doc->RemoveSystemEventListener(NS_LITERAL_STRING("DOMMouseScroll"), this,
+                                     true);
+      doc->RemoveSystemEventListener(NS_LITERAL_STRING("mousedown"), this,
+                                     true);
+      doc->RemoveSystemEventListener(NS_LITERAL_STRING("mouseup"), this, true);
+      doc->RemoveSystemEventListener(NS_LITERAL_STRING("keydown"), this, true);
+    }
+
+    // remove the popuphidden listener from tooltip
+    currentTooltip->RemoveSystemEventListener(NS_LITERAL_STRING("popuphiding"), this, false);
+  }
+
+  // kill any ongoing timers
+  KillTooltipTimer();
+  mSourceNode = nullptr;
+#ifdef MOZ_XUL
+  mLastTreeCol = nullptr;
+#endif
+
+  return NS_OK;
+}
+
+void
+nsXULTooltipListener::KillTooltipTimer()
+{
+  if (mTooltipTimer) {
+    mTooltipTimer->Cancel();
+    mTooltipTimer = nullptr;
+    mTargetNode = nullptr;
+  }
+}
+
+void
+nsXULTooltipListener::sTooltipCallback(nsITimer *aTimer, void *aListener)
+{
+  RefPtr<nsXULTooltipListener> instance = mInstance;
+  if (instance)
+    instance->ShowTooltip();
+}
+
+#ifdef MOZ_XUL
+nsresult
+nsXULTooltipListener::GetSourceTreeBoxObject(nsITreeBoxObject** aBoxObject)
+{
+  *aBoxObject = nullptr;
+
+  nsCOMPtr<nsIContent> sourceNode = do_QueryReferent(mSourceNode);
+  if (mIsSourceTree && sourceNode) {
+    nsCOMPtr<nsIDOMXULElement> xulEl(do_QueryInterface(sourceNode->GetParent()));
+    if (xulEl) {
+      nsCOMPtr<nsIBoxObject> bx;
+      xulEl->GetBoxObject(getter_AddRefs(bx));
+      nsCOMPtr<nsITreeBoxObject> obx(do_QueryInterface(bx));
+      if (obx) {
+        *aBoxObject = obx;
+        NS_ADDREF(*aBoxObject);
+        return NS_OK;
+      }
+    }
+  }
+  return NS_ERROR_FAILURE;
+}
+#endif
diff --git a/layout/xul/nsXULTooltipListener.h b/layout/xul/nsXULTooltipListener.h
new file mode 100644
index 0000000000..51e0a2c3f6
--- /dev/null
+++ b/layout/xul/nsXULTooltipListener.h
@@ -0,0 +1,102 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsXULTooltipListener_h__
+#define nsXULTooltipListener_h__
+
+#include "nsIDOMEventListener.h"
+#include "nsIDOMMouseEvent.h"
+#include "nsIDOMElement.h"
+#include "nsITimer.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+#ifdef MOZ_XUL
+#include "nsITreeBoxObject.h"
+#include "nsITreeColumns.h"
+#endif
+#include "nsWeakPtr.h"
+#include "mozilla/Attributes.h"
+
+class nsIContent;
+
+class nsXULTooltipListener final : public nsIDOMEventListener
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIDOMEVENTLISTENER
+
+  void MouseOut(nsIDOMEvent* aEvent);
+  void MouseMove(nsIDOMEvent* aEvent);
+
+  nsresult AddTooltipSupport(nsIContent* aNode);
+  nsresult RemoveTooltipSupport(nsIContent* aNode);
+  static nsXULTooltipListener* GetInstance() {
+    if (!mInstance)
+      mInstance = new nsXULTooltipListener();
+    return mInstance;
+  }
+  static void ClearTooltipCache() { mInstance = nullptr; }
+
+protected:
+
+  nsXULTooltipListener();
+  ~nsXULTooltipListener();
+
+  // pref callback for when the "show tooltips" pref changes
+  static bool sShowTooltips;
+  static uint32_t sTooltipListenerCount;
+
+  void KillTooltipTimer();
+
+#ifdef MOZ_XUL
+  void CheckTreeBodyMove(nsIDOMMouseEvent* aMouseEvent);
+  nsresult GetSourceTreeBoxObject(nsITreeBoxObject** aBoxObject);
+#endif
+
+  nsresult ShowTooltip();
+  void LaunchTooltip();
+  nsresult HideTooltip();
+  nsresult DestroyTooltip();
+  // This method tries to find a tooltip for aTarget.
+  nsresult FindTooltip(nsIContent* aTarget, nsIContent** aTooltip);
+  // This method calls FindTooltip and checks that the tooltip
+  // can be really used (i.e. tooltip is not a menu).
+  nsresult GetTooltipFor(nsIContent* aTarget, nsIContent** aTooltip);
+
+  static nsXULTooltipListener* mInstance;
+  static void ToolbarTipsPrefChanged(const char *aPref, void *aClosure);
+
+  nsWeakPtr mSourceNode;
+  nsWeakPtr mTargetNode;
+  nsWeakPtr mCurrentTooltip;
+
+  // a timer for showing the tooltip
+  nsCOMPtr<nsITimer> mTooltipTimer;
+  static void sTooltipCallback (nsITimer* aTimer, void* aListener);
+
+  // screen coordinates of the last mousemove event, stored so that the
+  // tooltip can be opened at this location.
+  int32_t mMouseScreenX, mMouseScreenY;
+
+  // various constants for tooltips
+  enum {
+    kTooltipMouseMoveTolerance = 7     // 7 pixel tolerance for mousemove event
+  };
+
+  // flag specifying if the tooltip has already been displayed by a MouseMove
+  // event. The flag is reset on MouseOut so that the tooltip will display
+  // the next time the mouse enters the node (bug #395668).
+  bool mTooltipShownOnce;
+
+#ifdef MOZ_XUL
+  // special members for handling trees
+  bool mIsSourceTree;
+  bool mNeedTitletip;
+  int32_t mLastTreeRow;
+  nsCOMPtr<nsITreeColumn> mLastTreeCol;
+#endif
+};
+
+#endif // nsXULTooltipListener
diff --git a/layout/xul/reftest/image-scaling-min-height-1-ref.xul b/layout/xul/reftest/image-scaling-min-height-1-ref.xul
new file mode 100644
index 0000000000..595450fe47
--- /dev/null
+++ b/layout/xul/reftest/image-scaling-min-height-1-ref.xul
@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml">
+<html:style><![CDATA[
+
+window { -moz-box-align: start; -moz-box-pack: start }
+hbox { background: yellow }
+vbox { background: blue; width: 15px; height: 15px }
+
+]]></html:style>
+
+<hbox><vbox /><label value="a b c d e f" /></hbox>
+
+</window>
diff --git a/layout/xul/reftest/image-scaling-min-height-1.xul b/layout/xul/reftest/image-scaling-min-height-1.xul
new file mode 100644
index 0000000000..5c45d6b0c9
--- /dev/null
+++ b/layout/xul/reftest/image-scaling-min-height-1.xul
@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml">
+<html:style><![CDATA[
+
+window { -moz-box-align: start; -moz-box-pack: start }
+hbox { background: yellow }
+image { background: blue; min-width: 15px; min-height: 15px }
+
+]]></html:style>
+
+<hbox><image /><label value="a b c d e f" /></hbox>
+
+</window>
diff --git a/layout/xul/reftest/image-size-ref.xul b/layout/xul/reftest/image-size-ref.xul
new file mode 100644
index 0000000000..c67364686b
--- /dev/null
+++ b/layout/xul/reftest/image-size-ref.xul
@@ -0,0 +1,115 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml">
+
+<html:style>
+div { margin: 0px; line-height: 0px; }
+div div { background: blue; display: inline; float: left; } 
+</html:style>
+
+<html:div><html:img
+      src="image4x3.png" style="width: 40px; height: 30px;"/><html:img
+      src="image4x3.png" style="width: 80px; height: 20px;"/><html:img
+      src="image4x3.png" style="width: 10px; height: 70px;"/><html:img
+      src="image4x3.png" style="width: 80px; height: 60px;"/><html:img
+      src="image4x3.png" style="width: 80px; height: 60px;"/><html:img
+      src="image4x3.png" style="width: 20px; height: 15px;"/><html:img
+      src="image4x3.png" style="width: 20px; height: 15px;"/><html:img
+      src="image4x3.png" style="width: 40px; height: 30px; border: 8px solid green;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 80px; height: 64px; border: 8px solid yellow;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 72px; height: 58px; border: 8px solid green;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 24px; height: 22px; border: 8px solid yellow;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 24px; height: 22px; border: 8px solid green;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 74px; height: 53px; border: solid yellow; border-top-width: 1px; border-right-width: 2px; border-bottom-width: 4px; border-left-width: 8px;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 18px; height: 11px; border: solid green; border-top-width: 1px; border-right-width: 2px; border-bottom-width: 4px; border-left-width: 8px;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="width: 40px; height: 30px;"/><html:img
+      src="image4x3.png" style="width: 80px; height: 20px;"/><html:img
+      src="image4x3.png" style="width: 10px; height: 70px;"/><html:img
+      src="image4x3.png" style="width: 80px; height: 60px;"/><html:img
+      src="image4x3.png" style="height: 80px; height: 60px;"/><html:img
+      src="image4x3.png" style="width: 20px; height: 15px;"/><html:img
+      src="image4x3.png" style="width: 20px; height: 15px;"/><html:img
+      src="image4x3.png" style="width: 60px; height: 25px;"/><html:img
+      src="image4x3.png" style="width: 20px; height: 75px;"/><html:img
+      src="image4x3.png" style="width: 80px; height: 64px; padding: 8px; box-sizing: border-box;"/><html:img
+      src="image4x3.png" style="width: 72px; height: 58px; padding: 8px; box-sizing: border-box;"/><html:img
+      src="image4x3.png" style="width: 24px; height: 22px; padding: 8px; box-sizing: border-box;"/><html:img
+      src="image4x3.png" style="width: 24px; height: 22px; padding: 8px; box-sizing: border-box;"/><html:img
+      src="image4x3.png" style="width: 67px; height: 60px; padding: 4px 2px 8px 1px; box-sizing: border-box;"/><html:img
+      src="image4x3.png" style="width: 11px; height: 18px; padding: 4px 2px 8px 1px; box-sizing: border-box;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="width: 20px; height: 15px;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="width: 20px; height: 15px;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="width: 30px; height: 22.5px"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="width: 20px; height: 15px;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="width: 20px; height: 15px;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="width 30px; height: 22.5px;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 24px; height: 22px; border: 8px solid green;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 24px; height: 22px; border: 8px solid green;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="width: 40px; height: 30px;"/><html:img
+      src="image4x3.png" style="width: 40px; height: 30px;"/><html:img
+      src="image4x3.png" style="width: 40px; height: 30px;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 60px; height: 49px; border: 8px solid green;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 112px; height: 88px; border: 8px solid yellow;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 96px; height: 76px; border: 8px solid green;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 112px; height: 88px; border: 8px solid yellow;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 106px; height: 77px; border: solid yellow; border-top-width: 1px; border-right-width: 2px; border-bottom-width: 4px; border-left-width: 8px;"/>
+</html:div>
+
+<html:div><html:img
+      src="image4x3.png" style="width: 60px; height: 45px;"/><html:img
+      src="image4x3.png" style="width: 120px; height: 90px;"/><html:img
+      src="image4x3.png" style="width 60px; height: 45px;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 60px; height: 49px; padding: 8px;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 112px; height: 88px; padding: 8px;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 96px; height: 76px; padding: 8px;"/><html:img
+      src="image4x3.png" style="box-sizing: border-box; width: 112px; height: 88px; padding: 8px;"/>
+</html:div>
+
+<html:div><html:div
+      style="width: 20px; height: 15px;"/><html:div
+      style="width: 80px; height: 60px;"/><html:div
+      style="width: 40px; height: 30px;"/><html:div
+      style="width: 10px; height: 8px;"/><html:div
+      style="width: 10px; height: 8px;"/>
+</html:div>
+    
+<html:div><html:div style="width: 20px; height: 15px;"/></html:div>
+
+<html:div><html:div style="width: 20px; height: 15px;"/></html:div>
+
+<html:div><html:div style="box-sizing: border-box; width: 24px; height: 22px; border: 8px solid green;"/></html:div>
+
+<html:div><html:div style="box-sizing: border-box; width: 24px; height: 22px; border: 8px solid green;"/></html:div>
+
+</window>
diff --git a/layout/xul/reftest/image-size.xul b/layout/xul/reftest/image-size.xul
new file mode 100644
index 0000000000..732dc51f3d
--- /dev/null
+++ b/layout/xul/reftest/image-size.xul
@@ -0,0 +1,123 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<hbox align="end">
+  <image src="image4x3.png"/>
+  <image src="image4x3.png" width="80" height="20"/>
+  <image src="image4x3.png" width="10" height="70"/>
+  <image src="image4x3.png" width="80"/>
+  <image src="image4x3.png" height="60"/>
+  <image src="image4x3.png" width="20"/>
+  <image src="image4x3.png" height="15"/>
+  <image src="image4x3.png" style="border: 8px solid green;"/>
+  <image src="image4x3.png" width="80" style="border: 8px solid yellow;"/>
+  <image src="image4x3.png" height="58" style="border: 8px solid green;"/>
+  <image src="image4x3.png" width="24" style="border: 8px solid yellow;"/>
+  <image src="image4x3.png" height="22" style="border: 8px solid green;"/>
+  <image src="image4x3.png" width="74"
+         style="border: 1px solid yellow; border-top-width: 1px; border-right-width: 2px; border-bottom-width: 4px; border-left-width: 8px;"/>
+  <image src="image4x3.png" height="11"
+         style="border: 1px solid green; border-top-width: 1px; border-right-width: 2px; border-bottom-width: 4px; border-left-width: 8px;"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" style="width: auto; height: auto;"/>
+  <image src="image4x3.png" style="width: 80px; height: 20px;"/>
+  <image src="image4x3.png" style="width: 10px; height: 70px;"/>
+  <image src="image4x3.png" style="width: 80px;"/>
+  <image src="image4x3.png" style="height: 60px;"/>
+  <image src="image4x3.png" style="width: 20px;"/>
+  <image src="image4x3.png" style="height: 15px;"/>
+  <image src="image4x3.png" style="width: 80px; height: 20px;" width="60" height="25"/>
+  <image src="image4x3.png" style="width: 10px; height: 70px;" width="20" height="75"/>
+  <image src="image4x3.png" style="width: 80px; padding: 8px;"/>
+  <image src="image4x3.png" style="height: 58px; padding: 8px;"/>
+  <image src="image4x3.png" style="width: 24px; padding: 8px;"/>
+  <image src="image4x3.png" style="height: 22px; padding: 8px;"/>
+  <image src="image4x3.png" style="width: 67px; padding: 4px 2px 8px 1px"/>
+  <image src="image4x3.png" style="height: 18px; padding: 4px 2px 8px 1px"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" maxwidth="20"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" maxheight="15"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" maxwidth="30" maxheight="25"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" style="max-width: 20px;"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" style="max-height: 15px;"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" style="max-width: 30px; max-height: 25px;"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" maxwidth="24" style="border: 8px solid green;"/>
+</hbox>
+<hbox align="end">
+  <image src="image4x3.png" maxheight="22" style="border: 8px solid green;"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" minwidth="20"/>
+  <image src="image4x3.png" minheight="20"/>
+  <image src="image4x3.png" minwidth="20" minheight="25"/>
+  <image src="image4x3.png" minwidth="60" style="border: 8px solid green;"/>
+  <image src="image4x3.png" minheight="88" style="border: 8px solid yellow;"/>
+  <image src="image4x3.png" minwidth="90" minheight="76" style="border: 8px solid green;"/>
+  <image src="image4x3.png" minwidth="112" minheight="76" style="border: 8px solid yellow;"/>
+  <image src="image4x3.png" minwidth="106"
+         style="border: 1px solid yellow; border-top-width: 1px; border-right-width: 2px; border-bottom-width: 4px; border-left-width: 8px;"/>
+</hbox>
+
+<hbox align="end">
+  <image src="image4x3.png" style="min-width: 60px;"/>
+  <image src="image4x3.png" style="min-height: 90px;"/>
+  <image src="image4x3.png" style="min-width 41px; min-height: 45px;"/>
+  <image src="image4x3.png" style="min-width: 60px; padding: 8px;"/>
+  <image src="image4x3.png" style="min-height: 88px; padding: 8px;"/>
+  <image src="image4x3.png" style="min-width: 90px; min-height: 76px; padding: 8px;"/>
+  <image src="image4x3.png" style="min-width: 112px; min-height: 76px; padding: 8px;"/>
+</hbox>
+
+<hbox align="start">
+  <image style="width: auto; height: auto; list-style-image: url(image4x3.png); -moz-image-region: rect(5px, 25px, 20px, 5px);"/>
+  <image width="80" style="list-style-image: url(image4x3.png); -moz-image-region: rect(5px, 25px, 20px, 5px);"/>
+  <image height="30" style="list-style-image: url(image4x3.png); -moz-image-region: rect(5px, 25px, 20px, 5px);"/>
+  <image style="width: 10px; list-style-image: url(image4x3.png); -moz-image-region: rect(5px, 25px, 21px, 5px);"/>
+  <image style="height: 8px; list-style-image: url(image4x3.png); -moz-image-region: rect(5px, 25px, 21px, 5px);"/>
+</hbox>
+
+<hbox align="end">
+  <image maxwidth="20"
+         style="list-style-image: url(image4x3.png); -moz-image-region: rect(5px, 25px, 20px, 5px);"/>
+</hbox>
+
+<hbox align="end">
+  <image maxheight="15"
+         style="list-style-image: url(image4x3.png); -moz-image-region: rect(5px, 25px, 20px, 5px);"/>
+</hbox>
+
+<hbox align="end">
+  <image maxwidth="24"
+         style="list-style-image: url(image4x3.png); -moz-image-region: rect(5px, 25px, 20px, 5px); border: 8px solid green;"/>
+</hbox>
+
+<hbox align="end">
+  <image maxheight="22"
+         style="list-style-image: url(image4x3.png); -moz-image-region: rect(5px, 25px, 20px, 5px); border: 8px solid green;"/>
+</hbox>
+
+</window>
diff --git a/layout/xul/reftest/image4x3.png b/layout/xul/reftest/image4x3.png
new file mode 100644
index 0000000000..6719bf5cec
--- /dev/null
+++ b/layout/xul/reftest/image4x3.png
diff --git a/layout/xul/reftest/popup-explicit-size-ref.xul b/layout/xul/reftest/popup-explicit-size-ref.xul
new file mode 100644
index 0000000000..4c864f1031
--- /dev/null
+++ b/layout/xul/reftest/popup-explicit-size-ref.xul
@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window align="start" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <label value="One"/>
+  <label value="Two"/>
+</window>
diff --git a/layout/xul/reftest/popup-explicit-size.xul b/layout/xul/reftest/popup-explicit-size.xul
new file mode 100644
index 0000000000..6f1bf85828
--- /dev/null
+++ b/layout/xul/reftest/popup-explicit-size.xul
@@ -0,0 +1,7 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window align="start" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <label value="One"/>
+  <popup height="40"/>
+  <label value="Two"/>
+</window>
diff --git a/layout/xul/reftest/reftest-stylo.list b/layout/xul/reftest/reftest-stylo.list
new file mode 100644
index 0000000000..5a96bfb117
--- /dev/null
+++ b/layout/xul/reftest/reftest-stylo.list
@@ -0,0 +1,14 @@
+# DO NOT EDIT! This is a auto-generated temporary list for Stylo testing
+fails-if(Android||B2G) skip-if((B2G&&browserIsRemote)||Mulet) == textbox-multiline-noresize.xul textbox-multiline-noresize.xul
+# reference is blank on Android (due to no native theme support?)
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == textbox-multiline-resize.xul textbox-multiline-resize.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == popup-explicit-size.xul popup-explicit-size.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+random-if(Android) skip-if((B2G&&browserIsRemote)||Mulet) == image-size.xul image-size.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == image-scaling-min-height-1.xul image-scaling-min-height-1.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
+skip-if((B2G&&browserIsRemote)||Mulet) == textbox-text-transform.xul textbox-text-transform.xul
+# Initial mulet triage: parity with B2G/B2G Desktop
diff --git a/layout/xul/reftest/reftest.list b/layout/xul/reftest/reftest.list
new file mode 100644
index 0000000000..39f3535774
--- /dev/null
+++ b/layout/xul/reftest/reftest.list
@@ -0,0 +1,6 @@
+fails-if(Android) == textbox-multiline-noresize.xul textbox-multiline-ref.xul # reference is blank on Android (due to no native theme support?)
+!= textbox-multiline-resize.xul textbox-multiline-ref.xul
+== popup-explicit-size.xul popup-explicit-size-ref.xul
+random-if(Android) == image-size.xul image-size-ref.xul
+== image-scaling-min-height-1.xul image-scaling-min-height-1-ref.xul
+== textbox-text-transform.xul textbox-text-transform-ref.xul
diff --git a/layout/xul/reftest/textbox-multiline-noresize.xul b/layout/xul/reftest/textbox-multiline-noresize.xul
new file mode 100644
index 0000000000..27945ae9a5
--- /dev/null
+++ b/layout/xul/reftest/textbox-multiline-noresize.xul
@@ -0,0 +1,5 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window align="start" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<textbox style="margin: 0;" multiline="true" width="100" height="100"/>
+</window>
diff --git a/layout/xul/reftest/textbox-multiline-ref.xul b/layout/xul/reftest/textbox-multiline-ref.xul
new file mode 100644
index 0000000000..23d279a75b
--- /dev/null
+++ b/layout/xul/reftest/textbox-multiline-ref.xul
@@ -0,0 +1,5 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window align="start" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<vbox style="-moz-appearance: textfield;" width="100" height="100"/>
+</window>
diff --git a/layout/xul/reftest/textbox-multiline-resize.xul b/layout/xul/reftest/textbox-multiline-resize.xul
new file mode 100644
index 0000000000..d7a25a6699
--- /dev/null
+++ b/layout/xul/reftest/textbox-multiline-resize.xul
@@ -0,0 +1,5 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window align="start" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<textbox style="margin: 0;" resizable="true" multiline="true" width="100" height="100"/>
+</window>
diff --git a/layout/xul/reftest/textbox-text-transform-ref.xul b/layout/xul/reftest/textbox-text-transform-ref.xul
new file mode 100644
index 0000000000..cbe95e0797
--- /dev/null
+++ b/layout/xul/reftest/textbox-text-transform-ref.xul
@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<label value="UPPERCASE"/>
+<label value="lowercase"/>
+</window>
diff --git a/layout/xul/reftest/textbox-text-transform.xul b/layout/xul/reftest/textbox-text-transform.xul
new file mode 100644
index 0000000000..5de1c6af2b
--- /dev/null
+++ b/layout/xul/reftest/textbox-text-transform.xul
@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<label style="text-transform: uppercase" value="uppercase"/>
+<label style="text-transform: lowercase" value="LOWERCASE"/>
+</window>
diff --git a/layout/xul/test/browser.ini b/layout/xul/test/browser.ini
new file mode 100644
index 0000000000..3fa28b1536
--- /dev/null
+++ b/layout/xul/test/browser.ini
@@ -0,0 +1,8 @@
+[DEFAULT]
+
+[browser_bug685470.js]
+[browser_bug703210.js]
+[browser_bug706743.js]
+skip-if = (os == 'linux') # Bug 1157576
+[browser_bug1163304.js]
+skip-if = os != 'linux' && os != 'win' // Due to testing menubar behavior with keyboard
diff --git a/layout/xul/test/browser_bug1163304.js b/layout/xul/test/browser_bug1163304.js
new file mode 100644
index 0000000000..b8e9409ddf
--- /dev/null
+++ b/layout/xul/test/browser_bug1163304.js
@@ -0,0 +1,35 @@
+function test() {
+  waitForExplicitFinish();
+
+  let searchBar = BrowserSearch.searchBar;
+  searchBar.focus();
+
+  let DOMWindowUtils = EventUtils._getDOMWindowUtils();
+  is(DOMWindowUtils.IMEStatus, DOMWindowUtils.IME_STATUS_ENABLED,
+     "IME should be available when searchbar has focus");
+
+  let searchPopup = document.getElementById("PopupSearchAutoComplete");
+  searchPopup.addEventListener("popupshown", function (aEvent) {
+    searchPopup.removeEventListener("popupshown", arguments.callee);
+    setTimeout(function () {
+      is(DOMWindowUtils.IMEStatus, DOMWindowUtils.IME_STATUS_ENABLED,
+         "IME should be available even when the popup of searchbar is open");
+      searchPopup.addEventListener("popuphidden", function (aEvent) {
+        searchPopup.removeEventListener("popuphidden", arguments.callee);
+        setTimeout(function () {
+          is(DOMWindowUtils.IMEStatus, DOMWindowUtils.IME_STATUS_DISABLED,
+             "IME should not be available when menubar is active");
+          // Inactivate the menubar (and restore the focus to the searchbar
+          EventUtils.synthesizeKey("VK_ESCAPE", {});
+          is(DOMWindowUtils.IMEStatus, DOMWindowUtils.IME_STATUS_ENABLED,
+             "IME should be available after focus is back to the searchbar");
+          finish();
+        }, 0);
+      });
+      // Activate the menubar, then, the popup should be closed
+      EventUtils.synthesizeKey("VK_ALT", {});
+    }, 0);
+  });
+  // Open popup of the searchbar
+  EventUtils.synthesizeKey("VK_F4", {});
+}
diff --git a/layout/xul/test/browser_bug685470.js b/layout/xul/test/browser_bug685470.js
new file mode 100644
index 0000000000..c86231bc76
--- /dev/null
+++ b/layout/xul/test/browser_bug685470.js
@@ -0,0 +1,19 @@
+add_task(function* () {
+  const html = "<p id=\"p1\" title=\"tooltip is here\">This paragraph has a tooltip.</p>";
+  yield BrowserTestUtils.openNewForegroundTab(gBrowser, "data:text/html," + html);
+
+  yield new Promise(resolve => {
+    SpecialPowers.pushPrefEnv({"set": [["ui.tooltipDelay", 0]]}, resolve);
+  });
+
+  yield BrowserTestUtils.synthesizeMouseAtCenter("#p1", { type: "mousemove" },
+                                                 gBrowser.selectedBrowser);
+  yield BrowserTestUtils.synthesizeMouseAtCenter("#p1", { }, gBrowser.selectedBrowser);
+
+  // Wait until the tooltip timeout triggers that would normally have opened the popup.
+  yield new Promise(resolve => setTimeout(resolve, 0));
+  is(document.getElementById("aHTMLTooltip").state, "closed", "local tooltip is closed");
+  is(document.getElementById("remoteBrowserTooltip").state, "closed", "remote tooltip is closed");
+
+  gBrowser.removeCurrentTab();
+});
diff --git a/layout/xul/test/browser_bug703210.js b/layout/xul/test/browser_bug703210.js
new file mode 100644
index 0000000000..cfd626b1cd
--- /dev/null
+++ b/layout/xul/test/browser_bug703210.js
@@ -0,0 +1,33 @@
+add_task(function* () {
+  const url = "data:text/html," +
+    "<html onmousemove='event.stopPropagation()'" +
+    " onmouseenter='event.stopPropagation()' onmouseleave='event.stopPropagation()'" +
+    " onmouseover='event.stopPropagation()' onmouseout='event.stopPropagation()'>" +
+    "<p id=\"p1\" title=\"tooltip is here\">This paragraph has a tooltip.</p>" +
+    "<p id=\"p2\">This paragraph doesn't have tooltip.</p></html>";
+
+  let tab = yield BrowserTestUtils.openNewForegroundTab(gBrowser, url);
+  let browser = gBrowser.selectedBrowser;
+
+  yield new Promise(resolve => {
+    SpecialPowers.pushPrefEnv({"set": [["ui.tooltipDelay", 0]]}, resolve);
+  });
+
+  // Send a mousemove at a known position to start the test.
+  yield BrowserTestUtils.synthesizeMouseAtCenter("#p2", { type: "mousemove" }, browser);
+  let popupShownPromise = BrowserTestUtils.waitForEvent(document, "popupshown", false, event => {
+    is(event.originalTarget.localName, "tooltip", "tooltip is showing");
+    return true;
+  });
+  yield BrowserTestUtils.synthesizeMouseAtCenter("#p1", { type: "mousemove" }, browser);
+  yield popupShownPromise;
+
+  let popupHiddenPromise = BrowserTestUtils.waitForEvent(document, "popuphidden", false, event => {
+    is(event.originalTarget.localName, "tooltip", "tooltip is hidden");
+    return true;
+  });
+  yield BrowserTestUtils.synthesizeMouseAtCenter("#p2", { type: "mousemove" }, browser);
+  yield popupHiddenPromise;
+
+  gBrowser.removeCurrentTab();
+});
diff --git a/layout/xul/test/browser_bug706743.js b/layout/xul/test/browser_bug706743.js
new file mode 100644
index 0000000000..b7262e812b
--- /dev/null
+++ b/layout/xul/test/browser_bug706743.js
@@ -0,0 +1,84 @@
+add_task(function* () {
+  const url = "data:text/html,<html><head></head><body>" +
+    "<a id=\"target\" href=\"about:blank\" title=\"This is tooltip text\" " +
+            "style=\"display:block;height:20px;margin:10px;\" " +
+            "onclick=\"return false;\">here is an anchor element</a></body></html>";
+
+  let tab = yield BrowserTestUtils.openNewForegroundTab(gBrowser, url);
+  let browser = gBrowser.selectedBrowser;
+
+  yield new Promise(resolve => {
+    SpecialPowers.pushPrefEnv({"set": [["ui.tooltipDelay", 0]]}, resolve);
+  });
+
+  // Send a mousemove at a known position to start the test.
+  yield BrowserTestUtils.synthesizeMouse("#target", -5, -5, { type: "mousemove" }, browser);
+
+  // show tooltip by mousemove into target.
+  let popupShownPromise = BrowserTestUtils.waitForEvent(document, "popupshown");
+  yield BrowserTestUtils.synthesizeMouse("#target", 5, 15, { type: "mousemove" }, browser);
+  yield popupShownPromise;
+
+  // hide tooltip by mousemove to outside.
+  let popupHiddenPromise = BrowserTestUtils.waitForEvent(document, "popuphidden");
+  yield BrowserTestUtils.synthesizeMouse("#target", -5, 15, { type: "mousemove" }, browser);
+  yield popupHiddenPromise;
+
+  // mousemove into the target and start drag by emulation via nsIDragService.
+  // Note that on some platforms, we cannot actually start the drag by
+  // synthesized events.  E.g., Windows waits an actual mousemove event after
+  // dragstart.
+
+  // Emulate a buggy mousemove event.  widget might dispatch mousemove event
+  // during drag.
+
+  function tooltipNotExpected()
+  {
+    ok(false, "tooltip is shown during drag");
+  }
+  addEventListener("popupshown", tooltipNotExpected, true);
+
+  let dragService = Components.classes["@mozilla.org/widget/dragservice;1"].
+                      getService(Components.interfaces.nsIDragService);
+  dragService.startDragSession();
+  yield BrowserTestUtils.synthesizeMouse("#target", 5, 15, { type: "mousemove" }, browser);
+
+  yield new Promise(resolve => setTimeout(resolve, 100));
+  removeEventListener("popupshown", tooltipNotExpected, true);
+  dragService.endDragSession(true);
+
+  yield BrowserTestUtils.synthesizeMouse("#target", -5, -5, { type: "mousemove" }, browser);
+
+  // If tooltip listener used a flag for managing D&D state, we would need
+  // to test if the tooltip is shown after drag.
+
+  // show tooltip by mousemove into target.
+  popupShownPromise = BrowserTestUtils.waitForEvent(document, "popupshown");
+  yield BrowserTestUtils.synthesizeMouse("#target", 5, 15, { type: "mousemove" }, browser);
+  yield popupShownPromise;
+
+  // hide tooltip by mousemove to outside.
+  popupHiddenPromise = BrowserTestUtils.waitForEvent(document, "popuphidden");
+  yield BrowserTestUtils.synthesizeMouse("#target", -5, 15, { type: "mousemove" }, browser);
+  yield popupHiddenPromise;
+
+  // Show tooltip after mousedown
+  popupShownPromise = BrowserTestUtils.waitForEvent(document, "popupshown");
+  yield BrowserTestUtils.synthesizeMouse("#target", 5, 15, { type: "mousemove" }, browser);
+  yield popupShownPromise;
+
+  popupHiddenPromise = BrowserTestUtils.waitForEvent(document, "popuphidden");
+  yield BrowserTestUtils.synthesizeMouse("#target", 5, 15, { type: "mousedown" }, browser);
+  yield popupHiddenPromise;
+
+  yield BrowserTestUtils.synthesizeMouse("#target", 5, 15, { type: "mouseup" }, browser);
+  yield BrowserTestUtils.synthesizeMouse("#target", -5, 15, { type: "mousemove" }, browser);
+
+  ok(true, "tooltips appear properly");
+
+  gBrowser.removeCurrentTab();
+});
+
+
+
+
diff --git a/layout/xul/test/chrome.ini b/layout/xul/test/chrome.ini
new file mode 100644
index 0000000000..2a647b6b71
--- /dev/null
+++ b/layout/xul/test/chrome.ini
@@ -0,0 +1,24 @@
+[DEFAULT]
+skip-if = os == 'android'
+support-files =
+  window_resizer.xul
+  window_resizer_element.xul
+
+[test_bug159346.xul]
+[test_bug372685.xul]
+[test_bug381167.xhtml]
+[test_bug393970.xul]
+[test_bug398982-1.xul]
+[test_bug398982-2.xul]
+[test_bug467442.xul]
+[test_bug477754.xul]
+[test_bug703150.xul]
+[test_bug987230.xul]
+skip-if = os == 'linux' # No native mousedown event on Linux
+[test_popupReflowPos.xul]
+[test_popupSizeTo.xul]
+[test_popupZoom.xul]
+[test_resizer.xul]
+[test_stack.xul]
+[test_submenuClose.xul]
+[test_windowminmaxsize.xul]
diff --git a/layout/xul/test/mochitest.ini b/layout/xul/test/mochitest.ini
new file mode 100644
index 0000000000..540abc730b
--- /dev/null
+++ b/layout/xul/test/mochitest.ini
@@ -0,0 +1,12 @@
+[DEFAULT]
+
+[test_bug386386.html]
+[test_bug394800.xhtml]
+[test_bug511075.html]
+skip-if = toolkit == 'android' #bug 798806
+[test_bug563416.html]
+[test_bug1197913.xul]
+skip-if = toolkit == 'android'
+[test_resizer_incontent.xul]
+[test_splitter.xul]
+skip-if = toolkit == 'android' # no XUL theme
diff --git a/layout/xul/test/test_bug1197913.xul b/layout/xul/test/test_bug1197913.xul
new file mode 100644
index 0000000000..6f922402d0
--- /dev/null
+++ b/layout/xul/test/test_bug1197913.xul
@@ -0,0 +1,68 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1197913
+-->
+<window title="Mozilla Bug 1197913"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="SimpleTest.waitForFocus(nextTest, window)">
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"/>
+
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1197913"
+     target="_blank">Mozilla Bug 1197913</a>
+  </body>
+
+  <hbox align="center" pack="center">
+    <menulist>
+      <menupopup>
+        <menuitem label="Car" />
+        <menuitem label="Taxi" id="target" />
+        <menuitem label="Bus" />
+      </menupopup>
+    </menulist>
+  </hbox>
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+  SimpleTest.waitForExplicitFinish();
+
+  let menulist = document.getElementsByTagName("menulist")[0];
+  let menuitem = document.getElementById("target");
+
+  function onDOMMenuItemActive(e) {
+    menuitem.removeEventListener("DOMMenuItemActive", onDOMMenuItemActive);
+
+    synthesizeMouse(menuitem, 0, 0, { type: "mousemove" });
+    synthesizeMouse(menuitem, -1, 0, { type: "mousemove" });
+
+    setTimeout(() => {
+      if (navigator.platform.toLowerCase().startsWith("win")) {
+        ok(menuitem.getAttribute("_moz-menuactive"));
+      } else {
+        ok(!menuitem.getAttribute("_moz-menuactive"));
+      }
+
+      SimpleTest.finish();
+    });
+  }
+
+  function onPopupShown(e) {
+    menulist.removeEventListener("popupshown", onPopupShown);
+    menuitem.addEventListener("DOMMenuItemActive", onDOMMenuItemActive);
+    synthesizeMouse(menuitem, 0, 0, { type: "mousemove" });
+    synthesizeMouse(menuitem, 1, 0, { type: "mousemove" });
+  }
+
+  function nextTest(e) {
+    menulist.addEventListener("popupshown", onPopupShown);
+    synthesizeMouseAtCenter(menulist, {});
+  }
+
+  ]]>
+  </script>
+</window>
diff --git a/layout/xul/test/test_bug159346.xul b/layout/xul/test/test_bug159346.xul
new file mode 100644
index 0000000000..4ef34fe323
--- /dev/null
+++ b/layout/xul/test/test_bug159346.xul
@@ -0,0 +1,135 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        title="Test for Bug 159346">
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=159346
+-->
+
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+
+<scrollbar id="scrollbar" curpos="0" maxpos="500"/>
+
+<script class="testbody" type="application/javascript">
+<![CDATA[
+
+var scrollbar = document.getElementById("scrollbar");
+var downButton =
+  document.getAnonymousElementByAttribute(scrollbar, "sbattr",
+                                          "scrollbar-down-bottom");
+
+function init()
+{
+  downButton.style.display = "-moz-box";
+  SimpleTest.executeSoon(doTest1);
+}
+
+function getCurrentPos()
+{
+  return Number(scrollbar.getAttribute("curpos"));
+}
+
+function doTest1()
+{
+  var lastPos = 0;
+
+  synthesizeMouseAtCenter(downButton, { type: "mousedown" });
+  ok(getCurrentPos() > lastPos,
+     "scrollbar didn't change curpos by mousedown #1");
+  lastPos = getCurrentPos();
+
+  setTimeout(function () {
+    ok(getCurrentPos() > lastPos,
+       "scrollbar didn't change curpos by auto repeat #1");
+    synthesizeMouseAtCenter(downButton, { type: "mouseup" });
+    lastPos = getCurrentPos();
+
+    setTimeout(function () {
+      is(getCurrentPos(), lastPos,
+         "scrollbar changed curpos after mouseup #1");
+      SimpleTest.executeSoon(doTest2);
+    }, 1000);
+  }, 1000);
+}
+
+function doTest2()
+{
+  SpecialPowers.setIntPref("ui.scrollbarButtonAutoRepeatBehavior", 0);
+
+  scrollbar.setAttribute("curpos", 0);
+  var lastPos = 0;
+
+  synthesizeMouseAtCenter(downButton, { type: "mousedown" });
+  ok(getCurrentPos() > lastPos,
+     "scrollbar didn't change curpos by mousedown #2");
+  lastPos = getCurrentPos();
+
+  synthesizeMouse(downButton, -10, -10, { type: "mousemove" });
+  lastPos = getCurrentPos();
+
+  setTimeout(function () {
+    is(getCurrentPos(), lastPos,
+       "scrollbar changed curpos by auto repeat when cursor is outside of scrollbar button #2");
+    synthesizeMouseAtCenter(downButton, { type: "mousemove" });
+    lastPos = getCurrentPos();
+
+    setTimeout(function () {
+      ok(getCurrentPos() > lastPos,
+         "scrollbar didn't change curpos by mousemove after cursor is back on the scrollbar button #2");
+      synthesizeMouseAtCenter(downButton, { type: "mouseup" });
+      SimpleTest.executeSoon(doTest3);
+    }, 1000);
+  }, 1000);
+}
+
+function doTest3()
+{
+  SpecialPowers.setIntPref("ui.scrollbarButtonAutoRepeatBehavior", 1);
+
+  scrollbar.setAttribute("curpos", 0);
+  var lastPos = 0;
+
+  synthesizeMouseAtCenter(downButton, { type: "mousedown" });
+  ok(getCurrentPos() > lastPos,
+     "scrollbar didn't change curpos by mousedown #3");
+  synthesizeMouse(downButton, -10, -10, { type: "mousemove" });
+  lastPos = getCurrentPos();
+
+  setTimeout(function () {
+    ok(getCurrentPos() > lastPos,
+       "scrollbar didn't change curpos by auto repeat when cursor is outside of scrollbar button #3");
+    synthesizeMouseAtCenter(downButton, { type: "mousemove" });
+    lastPos = getCurrentPos();
+
+    setTimeout(function () {
+      ok(getCurrentPos() > lastPos,
+         "scrollbar didn't change curpos by mousemove after cursor is back on the scrollbar button #3");
+      synthesizeMouseAtCenter(downButton, { type: "mouseup" });
+
+      SpecialPowers.clearUserPref("ui.scrollbarButtonAutoRepeatBehavior");
+      SimpleTest.finish();
+    }, 1000);
+  }, 1000);
+}
+
+SimpleTest.waitForExplicitFinish();
+
+]]>
+</script>
+
+<body  id="html_body" xmlns="http://www.w3.org/1999/xhtml">
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=159346">Mozilla Bug 159346</a>
+<p id="display"></p>
+
+<pre id="test">
+</pre>
+<script>
+addLoadEvent(init);
+</script>
+</body>
+
+
+</window>
diff --git a/layout/xul/test/test_bug372685.xul b/layout/xul/test/test_bug372685.xul
new file mode 100644
index 0000000000..09cc2be205
--- /dev/null
+++ b/layout/xul/test/test_bug372685.xul
@@ -0,0 +1,49 @@
+<?xml version="1.0"?>

+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>

+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>

+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"

+        xmlns:html="http://www.w3.org/1999/xhtml"

+        title="Test for Bug 372685">

+<!--

+https://bugzilla.mozilla.org/show_bug.cgi?id=372685

+-->

+

+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>

+

+<menuitem id="a" style="display: -moz-stack;">

+<box id="b" style="display: -moz-popup; ">

+<box id="c" style="position: fixed;"></box>

+</box>

+</menuitem>

+

+<script class="testbody" type="application/javascript">

+<![CDATA[

+

+function removestyles(i){

+          document.getElementById('a').removeAttribute('style');

+	  var x=document.getElementById('html_body').offsetHeight;

+	  is(0, 0, "this is a crash test, so always ok if we survive this far");

+          SimpleTest.finish();

+}

+function do_test() {

+          setTimeout(removestyles,200);

+}

+

+SimpleTest.waitForExplicitFinish();

+

+]]>

+</script>

+

+<body  id="html_body" xmlns="http://www.w3.org/1999/xhtml">

+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=372685">Mozilla Bug 372685</a>

+<p id="display"></p>

+

+<pre id="test">

+</pre>

+<script>

+addLoadEvent(do_test);

+</script>

+</body>

+

+

+</window>

diff --git a/layout/xul/test/test_bug381167.xhtml b/layout/xul/test/test_bug381167.xhtml
new file mode 100644
index 0000000000..3f98d7a4d6
--- /dev/null
+++ b/layout/xul/test/test_bug381167.xhtml
@@ -0,0 +1,49 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=381167
+-->
+<head>
+  <title>Test for Bug 381167</title>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=381167">Mozilla Bug 381167</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<xul:tree>
+  <xul:tree>
+    <xul:treechildren/>
+    <xul:treecol/>
+  </xul:tree>
+</xul:tree>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 381167 **/
+
+SimpleTest.waitForExplicitFinish();
+
+function closeit() {
+  var evt = document.createEvent('KeyboardEvent');
+                                 evt.initKeyEvent('keypress', true, true,
+                                 window,
+                                 true, false, false, false,
+                                 'W'.charCodeAt(0), 0);
+  window.dispatchEvent(evt);
+
+  setTimeout(finish, 200);
+}
+window.addEventListener('load', closeit, false);
+
+function finish()
+{
+  ok(true, "This is a mochikit version of a crash test. To complete is to pass.");
+  SimpleTest.finish();
+}
+</script>
+</pre>
+</body>
+</html>
diff --git a/layout/xul/test/test_bug386386.html b/layout/xul/test/test_bug386386.html
new file mode 100644
index 0000000000..b39ccede2d
--- /dev/null
+++ b/layout/xul/test/test_bug386386.html
@@ -0,0 +1,34 @@
+<html>
+<head><title>Testcase for bug 386386</title>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=386386
+-->
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+</head>
+<body>
+
+<iframe id="test386386" src="data:application/vnd.mozilla.xul+xml;charset=utf-8,%3C%3Fxml%20version%3D%221.0%22%3F%3E%0A%3Cwindow%3E%3C/window%3E"></iframe>
+
+<script class="testbody" type="application/javascript">
+
+function boom()
+{
+  var XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+  var doc = document.getElementById("test386386").contentDocument;
+  var observes = doc.createElementNS(XUL_NS, 'observes');
+  doc.removeChild(doc.documentElement);
+  doc.appendChild(observes);
+  is(0, 0, "Test is successful if we get here without crashing");
+  SimpleTest.finish();
+}
+
+function do_test() {
+  setTimeout(boom, 200);
+}
+SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout("untriaged");
+addLoadEvent(do_test);
+</script>
+
+</body>
+</html>
diff --git a/layout/xul/test/test_bug393970.xul b/layout/xul/test/test_bug393970.xul
new file mode 100644
index 0000000000..fcb0f9e43a
--- /dev/null
+++ b/layout/xul/test/test_bug393970.xul
@@ -0,0 +1,91 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<?xml-stylesheet href="data:text/css,description {min-width: 1px; padding: 2px;}" type="text/css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=393970
+-->
+<window title="Mozilla Bug 393970"
+  xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=393970"
+     target="_blank">Mozilla Bug 393970</a>
+  </body>
+
+  <hbox flex="1" pack="start" style="visibility: hidden;">
+    <grid min-width="1000" width="1000">
+      <columns>
+        <column flex="1"/>
+        <column flex="2"/>
+        <column flex="3"/>
+      </columns>
+      <rows id="rows1">
+        <row>
+          <description id="cell11">test1</description>
+          <description id="cell12">test2</description>
+          <description id="cell13">test3</description>
+        </row>
+        <rows id="rows2" flex="1">
+          <row>
+            <description id="cell21">test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1</description>
+            <description id="cell22">test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2</description>
+            <description id="cell23">test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3</description>
+          </row>
+          <rows id="rows3">
+            <row>
+              <description id="cell31">test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1 test1</description>
+              <description id="cell32">test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2 test2</description>
+              <description id="cell33">test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3 test3</description>
+            </row>
+          </rows>
+        </rows>
+      </rows>
+    </grid>
+  </hbox>
+
+  <!-- test code goes here -->
+  <script type="application/javascript"><![CDATA[
+    /** Test for Bug 393970 **/
+
+    if (navigator.platform.startsWith("Linux")) {
+      SimpleTest.expectAssertions(0, 24);
+    }
+
+    var tests = [
+      'overflow-x: hidden; overflow-y: hidden;',
+      'overflow-x: scroll; overflow-y: hidden;',
+      'overflow-x: hidden; overflow-y: scroll;',
+      'overflow-x: scroll; overflow-y: scroll;',
+    ];
+    var currentTest = -1;
+
+    function runNextTest() {
+      currentTest++;
+      if (currentTest >= tests.length) {
+        SimpleTest.finish();
+        return;
+      }
+
+      $("rows2").setAttribute("style", tests[currentTest]);
+      setTimeout(checkPositions, 0, tests[currentTest]);
+    }
+
+    function checkPositions(variant) {
+      for (var col = 1; col <= 3; col++) {
+        is($('cell1' + col).boxObject.x, $('cell2' + col).boxObject.x, "Cells (1," + col + ") and (2," + col + ") line up horizontally (with " + variant + ")");
+        is($('cell2' + col).boxObject.x, $('cell3' + col).boxObject.x, "Cells (2," + col + ") and (3," + col + ") line up horizontally (with " + variant + ")");
+      }
+      for (var row = 1; row <= 3; row++) {
+        is($('cell' + row + '1').boxObject.y, $('cell' + row + '2').boxObject.y, "Cells (" + row + ",1) and (" + row + ",2) line up vertically (with " + variant + ")");
+        is($('cell' + row + '2').boxObject.y, $('cell' + row + '3').boxObject.y, "Cells (" + row + ",2) and (" + row + ",3) line up vertically (with " + variant + ")");
+      }
+      runNextTest();
+    }
+ 
+    addLoadEvent(runNextTest);
+    SimpleTest.waitForExplicitFinish()
+   ]]></script>
+</window>
diff --git a/layout/xul/test/test_bug394800.xhtml b/layout/xul/test/test_bug394800.xhtml
new file mode 100644
index 0000000000..d2e2250e0d
--- /dev/null
+++ b/layout/xul/test/test_bug394800.xhtml
@@ -0,0 +1,39 @@
+<html xmlns="http://www.w3.org/1999/xhtml"
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<head>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=394800
+-->
+  <title>Test Mozilla bug 394800</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+
+<script class="testbody" type="application/javascript">
+
+function do_test()
+{
+  var x = document.getElementById("x");
+  x.parentNode.removeChild(x);
+  is(0, 0, "this is a crash/assertion test, so we're ok if we survived this far");
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+</script>
+</head>
+
+<body>
+
+<xul:menulist><xul:tooltip/><div><span><xul:hbox id="x"/></span></div></xul:menulist>
+
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=394800">Mozilla Bug 394800</a>
+<p id="display"></p>
+
+<pre id="test">
+</pre>
+
+<script>
+  addLoadEvent(do_test);
+</script>
+
+</body>
+</html>
diff --git a/layout/xul/test/test_bug398982-1.xul b/layout/xul/test/test_bug398982-1.xul
new file mode 100644
index 0000000000..39716ddf4c
--- /dev/null
+++ b/layout/xul/test/test_bug398982-1.xul
@@ -0,0 +1,31 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<menuitem xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+          xmlns:html="http://www.w3.org/1999/xhtml"
+          style="position: absolute; ">
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=398982
+-->
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+
+<tooltip type="zzz">
+<treecols/>
+</tooltip>
+
+<script xmlns="http://www.w3.org/1999/xhtml" class="testbody" type="application/javascript">
+<![CDATA[
+function doe() {
+  document.getElementsByTagName('menuitem')[0].removeAttribute('style');
+  is(0, 0, "Test is successful if we get here without crashing");
+  SimpleTest.finish();
+}
+function do_test() {
+  setTimeout(doe, 200);
+}
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(do_test);
+]]>
+</script>
+<html:body></html:body> <!-- XXX SimpleTest.showReport() requires a html:body -->
+</menuitem>
diff --git a/layout/xul/test/test_bug398982-2.xul b/layout/xul/test/test_bug398982-2.xul
new file mode 100644
index 0000000000..253695c390
--- /dev/null
+++ b/layout/xul/test/test_bug398982-2.xul
@@ -0,0 +1,33 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        title="Test for Bug 398982">
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=398982
+-->
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+
+<popupgroup style="position: absolute; ">
+<tooltip type="zzz">
+<treecols/>
+</tooltip>
+
+<script xmlns="http://www.w3.org/1999/xhtml" class="testbody" type="application/javascript">
+<![CDATA[
+function doe() {
+  document.getElementsByTagName('popupgroup')[0].removeAttribute('style');
+  is(0, 0, "Test is successful if we get here without crashing");
+  SimpleTest.finish();
+}
+function do_test() {
+  setTimeout(doe, 200);
+}
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(do_test);
+]]>
+</script>
+</popupgroup>
+<html:body></html:body> <!-- XXX SimpleTest.showReport() requires a html:body -->
+</window>
diff --git a/layout/xul/test/test_bug467442.xul b/layout/xul/test/test_bug467442.xul
new file mode 100644
index 0000000000..809e90cb88
--- /dev/null
+++ b/layout/xul/test/test_bug467442.xul
@@ -0,0 +1,54 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=467442
+-->
+<window title="Mozilla Bug 467442"
+        onload="onload()"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- test code goes here -->
+  <popupset>
+    <panel id="panel">
+      Hello.
+    </panel>
+  </popupset>
+  <hbox>
+    <button id="anchor" label="Anchor hello on here" style="transform: translate(100px, 0)"/>
+  </hbox>
+  <script type="application/javascript">
+  <![CDATA[
+
+  SimpleTest.waitForExplicitFinish();
+
+  function onload() {
+    /** Test for Bug 467442 **/
+    let panel = document.getElementById("panel");
+    let anchor = document.getElementById("anchor");
+
+    panel.addEventListener("popupshown", function onpopupshown() {
+      panel.removeEventListener("popupshown", onpopupshown);
+      let panelRect = panel.getBoundingClientRect();
+      let anchorRect = anchor.getBoundingClientRect();
+      is(panelRect.left, anchorRect.left, "Panel should be anchored to the button");
+      panel.addEventListener("popuphidden", function onpopuphidden() {
+        panel.removeEventListener("popuphidden", onpopuphidden);
+        SimpleTest.finish();
+      });
+      panel.hidePopup();
+    });
+
+    panel.openPopup(anchor, "after_start", 0, 0, false, false);
+  }
+
+  ]]>
+  </script>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=467442"
+     target="_blank">Mozilla Bug 467442</a>
+  </body>
+</window>
diff --git a/layout/xul/test/test_bug477754.xul b/layout/xul/test/test_bug477754.xul
new file mode 100644
index 0000000000..f72b1fffa5
--- /dev/null
+++ b/layout/xul/test/test_bug477754.xul
@@ -0,0 +1,49 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=477754
+-->
+<window title="Mozilla Bug 477754"
+  xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=477754"
+     target="_blank">Mozilla Bug 477754</a>
+  </body>
+
+  <hbox pack="center">
+    <label id="anchor" style="direction: rtl;" value="Anchor"/>
+  </hbox>
+  <panel id="testPopup" onpopupshown="doTest();">
+    <label value="I am a popup"/>
+  </panel>
+
+  <!-- test code goes here -->
+  <script type="application/javascript"><![CDATA[
+    /** Test for Bug 477754 **/
+    SimpleTest.waitForExplicitFinish();
+
+    let testPopup, testAnchor;
+
+    addEventListener("load", function () {
+      removeEventListener("load", arguments.callee, false);
+
+      testPopup = document.getElementById("testPopup");
+      testAnchor = document.getElementById("anchor");
+
+      testPopup.openPopup(testAnchor, "after_start", 10, 0, false, false);
+    }, false);
+
+    function doTest() {
+      is(Math.round(testAnchor.getBoundingClientRect().right -
+                    testPopup.getBoundingClientRect().right), 10,
+         "RTL popup's right offset should be equal to the x offset passed to openPopup");
+      testPopup.hidePopup();
+      SimpleTest.finish();
+    }
+
+   ]]></script>
+</window>
diff --git a/layout/xul/test/test_bug511075.html b/layout/xul/test/test_bug511075.html
new file mode 100644
index 0000000000..ecb2288840
--- /dev/null
+++ b/layout/xul/test/test_bug511075.html
@@ -0,0 +1,121 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=511075
+-->
+<head>
+  <title>Test for Bug 511075</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <style>
+  #scroller {
+    border: 1px solid black;
+  }
+  </style>
+</head>
+<body onload="runTests()">
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=511075">Mozilla Bug 511075</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 511075 **/
+
+SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout("untriaged");
+
+var tests = [
+  function() {
+    ok(true, "Setting location.hash should scroll.");
+    nextTest();
+    // Click the top scroll arrow.
+    var x = scroller.getBoundingClientRect().width - 5;
+    var y = 5;
+    // On MacOSX the top scroll arrow can be below the slider just above
+    // the bottom scroll arrow.
+    if (navigator.platform.indexOf("Mac") >= 0)
+      y = scroller.getBoundingClientRect().height - 40;
+    synthesizeMouse(scroller, x, y, { type : "mousedown" }, window);
+    synthesizeMouse(scroller, x, y, { type: "mouseup" }, window);
+  },
+  function() {
+    ok(true, "Clicking the top scroll arrow should scroll.");
+    nextTest();
+    // Click the bottom scroll arrow.
+    var x = scroller.getBoundingClientRect().width - 5;
+    var y = scroller.getBoundingClientRect().height - 25;
+    synthesizeMouse(scroller, x, y, { type : "mousedown" }, window);
+    synthesizeMouse(scroller, x, y, { type: "mouseup" }, window);
+  },
+  function() {
+    ok(true, "Clicking the bottom scroll arrow should scroll.");
+    nextTest();
+    // Click the scrollbar.
+    var x = scroller.getBoundingClientRect().width - 5;
+    synthesizeMouse(scroller, x, 40, { type : "mousedown" }, window);
+    synthesizeMouse(scroller, x, 40, { type: "mouseup" }, window);
+  },
+  function() {
+    ok(true, "Clicking the scrollbar should scroll");
+    nextTest();
+    // Click the scrollbar.
+    var x = scroller.getBoundingClientRect().width - 5;
+    var y = scroller.getBoundingClientRect().height - 50;
+    synthesizeMouse(scroller, x, y, { type : "mousedown" }, window);
+    synthesizeMouse(scroller, x, y, { type: "mouseup" }, window);
+  },
+  function() {
+    scroller.onscroll = null;
+    ok(true, "Clicking the scrollbar should scroll");
+    finish();
+  }
+];
+
+document.onmousedown = function () { return false; };
+document.onmouseup = function () { return true; };
+
+
+var scroller;
+var timer = 0;
+
+function failure() {
+  ok(false, scroller.onscroll + " did not run!");
+  scroller.onscroll = null;
+  finish();
+}
+
+function nextTest() {
+  clearTimeout(timer);
+  scroller.onscroll = tests.shift();
+  timer = setTimeout(failure, 2000);
+}
+
+function runTests() {
+  scroller = document.getElementById("scroller");
+  nextTest();
+  window.location.hash = "initialPosition";
+}
+
+function finish() {
+  document.onmousedown = null;
+  document.onmouseup = null;
+  clearTimeout(timer);
+  window.location.hash = "topPosition";
+  SimpleTest.finish();
+}
+
+
+</script>
+</pre>
+<div id="scroller" style="overflow: scroll; width: 100px; height: 150px;">
+<a id="topPosition" name="topPosition">top</a>
+<div style="width: 20000px; height: 20000px;"></div>
+<a id="initialPosition" name="initialPosition">initialPosition</a>
+<div style="width: 20000px; height: 20000px;"></div>
+</div>
+</body>
+</html>
diff --git a/layout/xul/test/test_bug563416.html b/layout/xul/test/test_bug563416.html
new file mode 100644
index 0000000000..dd245de0b0
--- /dev/null
+++ b/layout/xul/test/test_bug563416.html
@@ -0,0 +1,53 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=563416
+-->
+<head>
+  <title>Test for Bug 563416</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=563416">Mozilla Bug 563416</a>
+<p id="display"><iframe id="test" src='data:text/html,<textarea style="box-sizing:content-box; -moz-appearance:none; height: 0px; padding: 0px;" cols="20" rows="10">hsldkjvmshlkkajskdlfksdjflskdjflskdjflskdjflskdjfddddddddd</textarea>'></iframe></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 563416 **/
+
+var result = -1;
+var expected = -2;
+var i = 0;
+
+function runTest() {
+  i = 0;
+  var frame = document.getElementById('test');
+  frame.onload = function() {
+    var t = frame.contentDocument.documentElement.getElementsByTagName("textarea")[0];
+    expected = t.clientWidth + 10;
+    t.style.width = expected + 'px';
+    result = t.clientWidth;
+    if (i == 0) {
+      i++;
+      setTimeout(function(){frame.contentWindow.location.reload();},0);
+    }
+    else {
+      is(result, expected, "setting style.width changes clientWidth");
+      SimpleTest.finish();
+    }
+  }
+  frame.contentWindow.location.reload();
+}
+
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(runTest);
+
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/layout/xul/test/test_bug703150.xul b/layout/xul/test/test_bug703150.xul
new file mode 100644
index 0000000000..fab7d16774
--- /dev/null
+++ b/layout/xul/test/test_bug703150.xul
@@ -0,0 +1,69 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        title="Test for Bug 703150">
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=703150
+-->
+
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+
+<scrollbar id="scrollbar" curpos="0" maxpos="500"/>
+
+<script class="testbody" type="application/javascript">
+<![CDATA[
+
+var scrollbar = document.getElementById("scrollbar");
+var scrollbarThumb =
+  document.getAnonymousElementByAttribute(scrollbar, "sbattr",
+                                          "scrollbar-thumb");
+
+function doTest()
+{
+  function mousedownHandler(aEvent)
+  {
+    aEvent.stopPropagation();
+  }
+  window.addEventListener("mousedown", mousedownHandler, true);
+
+  // Wait for finishing reflow...
+  SimpleTest.executeSoon(function () {
+    synthesizeMouseAtCenter(scrollbarThumb, { type: "mousedown" });
+
+    is(scrollbar.getAttribute("curpos"), "0",
+       "scrollbar thumb has been moved already");
+
+    synthesizeMouseAtCenter(scrollbar, { type: "mousemove" });
+
+    ok(scrollbar.getAttribute("curpos") > 0,
+       "scrollbar thumb hasn't been dragged");
+
+    synthesizeMouseAtCenter(scrollbarThumb, { type: "mouseup" });
+
+    window.removeEventListener("mousedown", mousedownHandler, true);
+
+    SimpleTest.finish();
+  });
+}
+
+SimpleTest.waitForExplicitFinish();
+
+]]>
+</script>
+
+<body  id="html_body" xmlns="http://www.w3.org/1999/xhtml">
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=703150">Mozilla Bug 703150</a>
+<p id="display"></p>
+
+<pre id="test">
+</pre>
+<script>
+addLoadEvent(doTest);
+</script>
+</body>
+
+
+</window>
diff --git a/layout/xul/test/test_bug987230.xul b/layout/xul/test/test_bug987230.xul
new file mode 100644
index 0000000000..b2b47f4700
--- /dev/null
+++ b/layout/xul/test/test_bug987230.xul
@@ -0,0 +1,125 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=987230
+-->
+<window title="Mozilla Bug 987230"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="SimpleTest.waitForFocus(nextTest, window)">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=987230"
+     target="_blank">Mozilla Bug 987230</a>
+  </body>
+
+  <vbox>
+    <toolbar>
+      <toolbarbutton id="toolbarbutton-anchor"
+                     label="Anchor"
+                     consumeanchor="toolbarbutton-anchor"
+                     onclick="onAnchorClick(event)"
+                     style="padding: 50px !important; list-style-image: url(chrome://branding/content/icon32.png)"/>
+    </toolbar>
+    <spacer flex="1"/>
+    <hbox id="hbox-anchor"
+          style="padding: 20px"
+          onclick="onAnchorClick(event)">
+      <hbox id="inner-anchor"
+        consumeanchor="hbox-anchor"
+        >
+        Another anchor
+      </hbox>
+    </hbox>
+    <spacer flex="1"/>
+  </vbox>
+
+  <panel id="mypopup"
+         type="arrow"
+         onpopupshown="onMyPopupShown(event)"
+         onpopuphidden="onMyPopupHidden(event)">This is a test popup</panel>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+  /** Test for Bug 987230 **/
+  SimpleTest.waitForExplicitFinish();
+
+  SimpleTest.requestCompleteLog();
+
+  const Ci = Components.interfaces;
+  const Cc = Components.classes;
+
+  let platform = navigator.platform.toLowerCase();
+  let isWindows = platform.startsWith("win");
+  let mouseDown = isWindows ? 2 : 1;
+  let mouseUp = isWindows ? 4 : 2;
+  let mouseMove = isWindows ? 1 : 5;
+  let utils = window.QueryInterface(Ci.nsIInterfaceRequestor)
+                    .getInterface(Ci.nsIDOMWindowUtils);
+  let scale = utils.screenPixelsPerCSSPixel;
+
+
+  function synthesizeNativeMouseClick(aElement, aOffsetX, aOffsetY) {
+    let rect = aElement.getBoundingClientRect();
+    let win = aElement.ownerDocument.defaultView;
+    let x = aOffsetX + win.mozInnerScreenX + rect.left;
+    let y = aOffsetY + win.mozInnerScreenY + rect.top;
+
+    info("Sending mousedown+up for offsets: " + aOffsetX + ", " + aOffsetY +
+         "; innerscreen: " + win.mozInnerScreenX + ", " + win.mozInnerScreenY +
+         "; rect: " + rect.left + ", " + rect.top + ".");
+    info("Resulting x, y, scale: " + x + ", " + y + ", " + scale);
+    info("Final params: " + (x * scale) + ", " + (y * scale));
+    utils.sendNativeMouseEvent(x * scale, y * scale, mouseDown, 0, null);
+    utils.sendNativeMouseEvent(x * scale, y * scale, mouseUp, 0, null);
+  }
+
+  function onMyPopupHidden(e) {
+    ok(true, "Popup hidden");
+    if (outerAnchor.id == "toolbarbutton-anchor") {
+      popupHasShown = false;
+      outerAnchor = document.getElementById("hbox-anchor");
+      anchor = document.getElementById("inner-anchor");
+      nextTest();
+    } else {
+      //XXXgijs set mouse position back outside the iframe:
+      let frameRect = window.frameElement.getBoundingClientRect();
+      let outsideOfFrameX = (window.mozInnerScreenX + frameRect.width + 100) * scale;
+      let outsideOfFrameY = Math.max(0, window.mozInnerScreenY - 100) * scale;
+
+      info("Mousemove: " + outsideOfFrameX + ", " + outsideOfFrameY +
+           " (from innerscreen " + window.mozInnerScreenX + ", " + window.mozInnerScreenY +
+           " and rect width " + frameRect.width + " and scale " + scale + ")");
+      utils.sendNativeMouseEvent(outsideOfFrameX, outsideOfFrameY, mouseMove, 0, null);
+      SimpleTest.finish();
+    }
+  }
+
+  let popupHasShown = false;
+  function onMyPopupShown(e) {
+    popupHasShown = true;
+    synthesizeNativeMouseClick(outerAnchor, 5, 5);
+  }
+
+  function onAnchorClick(e) {
+    info("click: " + e.target.id);
+    ok(!popupHasShown, "Popup should only be shown once");
+    popup.openPopup(anchor, "bottomcenter topright");
+  }
+
+  let popup = document.getElementById("mypopup");
+  let outerAnchor = document.getElementById("toolbarbutton-anchor");
+  let anchor = document.getAnonymousElementByAttribute(outerAnchor, "class", "toolbarbutton-icon");
+
+  function nextTest(e) {
+    synthesizeMouse(outerAnchor, 5, 5, {});
+  }
+
+  ]]>
+  </script>
+</window>
diff --git a/layout/xul/test/test_popupReflowPos.xul b/layout/xul/test/test_popupReflowPos.xul
new file mode 100644
index 0000000000..deeeff62e6
--- /dev/null
+++ b/layout/xul/test/test_popupReflowPos.xul
@@ -0,0 +1,76 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<window title="XUL Panel reflow placement test"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript"><![CDATA[
+    SimpleTest.waitForExplicitFinish();
+
+    function openPopup()
+    {
+      synthesizeMouseAtCenter(document.getElementById("thebutton"), {}, window);
+    }
+
+    function popupShown(event)
+    {
+      document.getElementById("parent").className = "";
+
+      var buttonbcr = document.getElementById("thebutton").getBoundingClientRect();
+      var popupbcr = document.getElementById("thepopup").getOuterScreenRect();
+
+      ok(Math.abs(popupbcr.x - window.mozInnerScreenX - buttonbcr.x) < 3, "x pos is correct");
+      ok(Math.abs(popupbcr.y - window.mozInnerScreenY - buttonbcr.bottom) < 3, "y pos is correct");
+
+      event.target.hidePopup();
+    }
+
+    SimpleTest.waitForFocus(openPopup);
+   ]]></script>
+
+    <html:style>
+      .mbox {
+        display: inline-block;
+        width: 33%;
+        height: 50px;
+        background: green;
+        vertical-align: middle;
+      }
+      .orange {
+        background: orange;
+      }
+      .change > .mbox {
+        width: 60px;
+      }
+    </html:style>
+
+  <html:div style="width: 300px; height: 200px;">
+    <html:div id="parent" class="change" style="background: red; border: 1px solid black; width: 300px; height: 200px;">
+      <html:div class="mbox"></html:div>
+      <html:div class="mbox"></html:div>
+      <html:div class="mbox"></html:div>
+      <html:div class="mbox orange">
+
+          <button label="Show" type="menu" id="thebutton">
+            <menupopup id="thepopup" onpopupshown="popupShown(event)" onpopuphidden="SimpleTest.finish()">
+              <menuitem label="New"/>
+              <menuitem label="Open"/>
+              <menuitem label="Save"/>
+              <menuseparator/>
+              <menuitem label="Exit"/>
+            </menupopup>
+          </button>
+
+      </html:div>
+    </html:div>
+  </html:div>
+
+</window>
diff --git a/layout/xul/test/test_popupSizeTo.xul b/layout/xul/test/test_popupSizeTo.xul
new file mode 100644
index 0000000000..a135e19801
--- /dev/null
+++ b/layout/xul/test/test_popupSizeTo.xul
@@ -0,0 +1,55 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<!--
+XUL Panel sizeTo tests
+-->
+<window title="XUL Panel sizeTo tests"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript"><![CDATA[
+    SimpleTest.waitForExplicitFinish();
+
+    function openPopup()
+    {
+      document.getElementById("panel").
+        openPopupAtScreen(Math.round(window.mozInnerScreenX) + window.innerWidth - 130,
+                          Math.round(window.mozInnerScreenY) + window.innerHeight - 130);
+    }
+
+    function sizeAndCheck(width, height) {
+      var panel = document.getElementById("panel");
+      panel.sizeTo(width, height);
+      is(panel.getBoundingClientRect().width, width, "width is correct");
+      is(panel.getBoundingClientRect().height, height, "height is correct");
+
+    }
+    function popupShown(event)
+    {
+      var panel = document.getElementById("panel");
+      var bcr = panel.getBoundingClientRect();
+      // resize to 10px bigger in both dimensions.
+      sizeAndCheck(bcr.width+10, bcr.height+10);
+      // Same width, different height (based on *new* size from last sizeAndCheck)
+      sizeAndCheck(bcr.width+10, bcr.height);
+      // Same height, different width (also based on *new* size from last sizeAndCheck)
+      sizeAndCheck(bcr.width, bcr.height);
+      event.target.hidePopup();
+    }
+
+    SimpleTest.waitForFocus(openPopup);
+   ]]></script>
+
+<panel id="panel" onpopupshown="popupShown(event)" onpopuphidden="SimpleTest.finish()">
+  <resizer id="resizer" dir="bottomend" width="16" height="16"/>
+  <hbox width="50" height="50" flex="1"/>
+</panel>
+
+</window>
diff --git a/layout/xul/test/test_popupZoom.xul b/layout/xul/test/test_popupZoom.xul
new file mode 100644
index 0000000000..b8e15ba1d2
--- /dev/null
+++ b/layout/xul/test/test_popupZoom.xul
@@ -0,0 +1,57 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<window title="XUL Panel zoom test"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript"><![CDATA[
+    SimpleTest.waitForExplicitFinish();
+
+    var docviewer;
+    var savedzoom;
+
+    function openPopup()
+    {
+      docviewer = window.QueryInterface(Components.interfaces.nsIInterfaceRequestor)
+                        .getInterface(Components.interfaces.nsIWebNavigation)
+                        .QueryInterface(Components.interfaces.nsIDocShell)
+                        .contentViewer;
+      savedzoom = docviewer.fullZoom;
+      docviewer.fullZoom = 2;
+
+      document.getElementById("panel").
+        openPopup(document.getElementById("anchor"), "after_start", 0, 0, false, false, null);
+    }
+
+    function popupShown(event)
+    {
+      var panel = document.getElementById("panel");
+      var panelbcr = panel.getBoundingClientRect();
+      var anchorbcr = document.getElementById("anchor").getBoundingClientRect();
+
+      ok(Math.abs(panelbcr.x - anchorbcr.x) < 3, "x pos is correct");
+      ok(Math.abs(panelbcr.y - anchorbcr.bottom) < 3, "y pos is correct");
+
+      docviewer.fullZoom = savedzoom;
+
+      event.target.hidePopup();
+    }
+
+    SimpleTest.waitForFocus(openPopup);
+   ]]></script>
+
+<description id="anchor" value="Sometext to this some texts"/>
+<panel id="panel" onpopupshown="popupShown(event)" onpopuphidden="SimpleTest.finish()">
+  <resizer id="resizer" dir="bottomend" width="16" height="16"/>
+  <hbox width="50" height="50" flex="1"/>
+</panel>
+
+
+</window>
diff --git a/layout/xul/test/test_resizer.xul b/layout/xul/test/test_resizer.xul
new file mode 100644
index 0000000000..2ba971d059
--- /dev/null
+++ b/layout/xul/test/test_resizer.xul
@@ -0,0 +1,94 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<!--
+XUL <resizer> tests
+-->
+<window title="XUL resizer tests"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript"><![CDATA[
+    SimpleTest.waitForExplicitFinish();
+    SimpleTest.ignoreAllUncaughtExceptions();
+
+    function openPopup()
+    {
+      document.getElementById("panel").
+        openPopupAtScreen(Math.round(window.mozInnerScreenX) + window.innerWidth - 130,
+                          Math.round(window.mozInnerScreenY) + window.innerHeight - 130);
+    }
+
+    var step = 0;
+    function popupShown(event)
+    {
+      if (step == 0) {
+        // check to make sure that the popup cannot be resized past the edges of
+        // the content area
+        var resizerrect = document.getElementById("resizer").getBoundingClientRect();
+        synthesizeMouse(document.documentElement, resizerrect.left + 5, resizerrect.top + 5, { type:"mousedown" });
+        synthesizeMouse(document.documentElement, resizerrect.left + 2000, resizerrect.top + 2000, { type:"mousemove" });
+
+        // allow a one pixel variance as rounding is always done to the inside
+        // of a rectangle.
+        var popuprect = document.getElementById("panel").getBoundingClientRect();
+        ok(Math.round(popuprect.right) == window.innerWidth ||
+           Math.round(popuprect.right) == window.innerWidth - 1,
+           "resized to content edge width");
+        ok(Math.round(popuprect.bottom) == window.innerHeight ||
+           Math.round(popuprect.bottom) == window.innerHeight - 1,
+           "resized to content edge height");
+
+        resizerrect = document.getElementById("resizer").getBoundingClientRect();
+        synthesizeMouse(document.documentElement, resizerrect.left + 5, resizerrect.top + 5, { type:"mouseup" });
+      }
+      else {
+        // the popup is opened twice. Make sure that for the second time, the
+        // resized popup opens in the same direction as there should still be
+        // room for it
+        var popuprect = document.getElementById("panel").getBoundingClientRect();
+        is(Math.round(popuprect.left), window.innerWidth - 130, "reopen popup left");
+        is(Math.round(popuprect.top), window.innerHeight - 130, "reopen popup top");
+      }
+
+      event.target.hidePopup();
+    }
+
+    function doResizerWindowTests() {
+      step++;
+      if (step == 1) {
+        openPopup();
+        return;
+      }
+
+      if (/Mac/.test(navigator.platform)) {
+        window.open("window_resizer.xul", "_blank", "left=200,top=200,outerWidth=300,outerHeight=300,chrome");
+      }
+      else {
+        // Skip window_resizer.xul tests.
+        todo(false, "We can't test GTK and Windows native drag resizing implementations.");
+        // Run window_resizer_element.xul test only.
+        lastResizerTest();
+      }
+    }
+
+    function lastResizerTest()
+    {
+      window.open("window_resizer_element.xul", "_blank", "left=200,top=200,outerWidth=300,outerHeight=300,chrome");
+    }
+
+    SimpleTest.waitForFocus(openPopup);
+   ]]></script>
+
+<panel id="panel" onpopupshown="popupShown(event)" onpopuphidden="doResizerWindowTests()">
+  <resizer id="resizer" dir="bottomend" width="16" height="16"/>
+  <hbox width="50" height="50" flex="1"/>
+</panel>
+
+</window>
diff --git a/layout/xul/test/test_resizer_incontent.xul b/layout/xul/test/test_resizer_incontent.xul
new file mode 100644
index 0000000000..068bd5bb12
--- /dev/null
+++ b/layout/xul/test/test_resizer_incontent.xul
@@ -0,0 +1,42 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="/tests/SimpleTest/test.css" type="text/css"?>
+<!--
+This test ensures that a resizer in content doesn't resize the window.
+-->
+<window title="XUL resizer in content test"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript"><![CDATA[
+    SimpleTest.waitForExplicitFinish();
+
+    function testResizer()
+    { 
+      var oldScreenX = window.screenX;
+      var oldScreenY = window.screenY;
+      var oldWidth = window.outerWidth;
+      var oldHeight = window.outerHeight;
+      var resizer = document.getElementById("resizer");
+      synthesizeMouseAtCenter(resizer, { type:"mousedown" });
+      synthesizeMouse(resizer, 32, 32, { type:"mousemove" });
+      synthesizeMouse(resizer, 32, 32, { type:"mouseup" });
+      is(window.screenX, oldScreenX, "window not moved for non-chrome window screenX");
+      is(window.screenY, oldScreenY, "window not moved for non-chrome window screenY");
+      is(window.outerWidth, oldWidth, "window not moved for non-chrome window outerWidth");
+      is(window.outerHeight, oldHeight, "window not moved for non-chrome window outerHeight");
+      SimpleTest.finish();
+    }
+
+    SimpleTest.waitForFocus(testResizer);
+   ]]></script>
+
+  <resizer id="resizer" dir="bottomend" width="16" height="16"/>
+
+</window>
diff --git a/layout/xul/test/test_splitter.xul b/layout/xul/test/test_splitter.xul
new file mode 100644
index 0000000000..697ad4be88
--- /dev/null
+++ b/layout/xul/test/test_splitter.xul
@@ -0,0 +1,117 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="/tests/SimpleTest/test.css" type="text/css"?>
+<?xml-stylesheet href="data:text/css, hbox { border: 1px solid red; } vbox { border: 1px solid green }" type="text/css"?>
+<!--
+XUL <splitter> collapsing tests
+-->
+<window title="XUL splitter collapsing tests"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        orient="horizontal">
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript"><![CDATA[
+    SimpleTest.waitForExplicitFinish();
+
+    function dragSplitter(offsetX, callback) {
+      var splitterWidth = splitter.boxObject.width;
+      synthesizeMouse(splitter, splitterWidth / 2, 2, {type: "mousedown"});
+      synthesizeMouse(splitter, splitterWidth / 2, 1, {type: "mousemove"});
+      SimpleTest.executeSoon(function() {
+        SimpleTest.is(splitter.getAttribute("state"), "dragging", "The splitter should be dragged");
+        synthesizeMouse(splitter, offsetX, 1, {type: "mousemove"});
+        synthesizeMouse(splitter, offsetX, 1, {type: "mouseup"});
+        SimpleTest.executeSoon(callback);
+      });
+    }
+
+    function shouldBeCollapsed(where) {
+      SimpleTest.is(splitter.getAttribute("state"), "collapsed", "The splitter should be collapsed");
+      SimpleTest.is(splitter.getAttribute("substate"), where, "The splitter should be collapsed " + where);
+    }
+
+    function shouldNotBeCollapsed() {
+      SimpleTest.is(splitter.getAttribute("state"), "", "The splitter should not be collapsed");
+    }
+
+    function runPass(rightCollapsed, leftCollapsed, callback) {
+      var containerWidth = container.boxObject.width;
+      var isRTL = getComputedStyle(splitter, null).direction == "rtl";
+      dragSplitter(containerWidth, function() {
+        if (rightCollapsed) {
+          shouldBeCollapsed(isRTL ? "before" : "after");
+        } else {
+          shouldNotBeCollapsed();
+        }
+        dragSplitter(-containerWidth * 2, function() {
+          if (leftCollapsed) {
+            shouldBeCollapsed(isRTL ? "after" : "before");
+          } else {
+            shouldNotBeCollapsed();
+          }
+          dragSplitter(containerWidth / 2, function() {
+            // the splitter should never be collapsed in the middle
+            shouldNotBeCollapsed();
+            callback();
+          });
+        });
+      });
+    }
+
+    var splitter, container;
+    function runLTRTests(callback) {
+      splitter = document.getElementById("ltr-splitter");
+      container = splitter.parentNode;
+      splitter.setAttribute("collapse", "before");
+      runPass(false, true, function() {
+        splitter.setAttribute("collapse", "after");
+        runPass(true, false, function() {
+          splitter.setAttribute("collapse", "both");
+          runPass(true, true, callback);
+        });
+      });
+    }
+
+    function runRTLTests(callback) {
+      splitter = document.getElementById("rtl-splitter");
+      container = splitter.parentNode;
+      splitter.setAttribute("collapse", "before");
+      runPass(true, false, function() {
+        splitter.setAttribute("collapse", "after");
+        runPass(false, true, function() {
+          splitter.setAttribute("collapse", "both");
+          runPass(true, true, callback);
+        });
+      });
+    }
+
+    function runTests() {
+      runLTRTests(function() {
+        runRTLTests(function() {
+          SimpleTest.finish();
+        });
+      });
+    }
+
+    addLoadEvent(function() {SimpleTest.executeSoon(runTests);});
+   ]]></script>
+
+  <hbox style="max-width: 200px; height: 300px; direction: ltr;">
+    <vbox style="width: 100px; height: 300px;" flex="1"/>
+    <splitter id="ltr-splitter"/>
+    <vbox style="width: 100px; height: 300px;" flex="1"/>
+  </hbox>
+
+  <hbox style="max-width: 200px; height: 300px; direction: rtl;">
+    <vbox style="width: 100px; height: 300px;" flex="1"/>
+    <splitter id="rtl-splitter"/>
+    <vbox style="width: 100px; height: 300px;" flex="1"/>
+  </hbox>
+
+</window>
diff --git a/layout/xul/test/test_stack.xul b/layout/xul/test/test_stack.xul
new file mode 100644
index 0000000000..781a6f298e
--- /dev/null
+++ b/layout/xul/test/test_stack.xul
@@ -0,0 +1,327 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+
+<window align="start" title="XUL stack tests" onload="runTest()"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- a * before an expected value means an offset from the right or bottom edge -->
+  <stack id="stack">
+    <hbox id="left-top" left="10" top="12" width="20" height="24"
+                        expectedleft="10" expectedtop="12" expectedright="30" expectedbottom="36"
+                        stackwidth="30" stackheight="36"/>
+    <hbox id="start-top" start="10" top="12" width="20" height="24"
+                         expectedleft="10" expectedtop="12" expectedright="30" expectedbottom="36"
+                         stackwidth="30" stackheight="36"/>
+    <hbox id="right-bottom" right="10" bottom="12" width="20" height="24"
+                            expectedleft="*30" expectedtop="*36" expectedright="*10" expectedbottom="*12"
+                            stackwidth="30" stackheight="36"/>
+    <hbox id="end-bottom" end="10" bottom="12" width="20" height="24"
+                          expectedleft="*30" expectedtop="*36" expectedright="*10" expectedbottom="*12"
+                          stackwidth="30" stackheight="36"/>
+    <hbox id="left-bottom" left="18" bottom="15" width="16" height="19"
+                           expectedleft="18" expectedtop="*34" expectedright="34" expectedbottom="*15"
+                           stackwidth="34" stackheight="34"/>
+    <hbox id="start-bottom" start="18" bottom="15" width="16" height="19"
+                            expectedleft="18" expectedtop="*34" expectedright="34" expectedbottom="*15"
+                            stackwidth="34" stackheight="34"/>
+    <hbox id="right-top" right="5" top="8" width="10" height="11"
+                         expectedleft="*15" expectedtop="8" expectedright="*5" expectedbottom="19"
+                         stackwidth="15" stackheight="19"/>
+    <hbox id="end-top" end="5" top="8" width="10" height="11"
+                       expectedleft="*15" expectedtop="8" expectedright="*5" expectedbottom="19"
+                       stackwidth="15" stackheight="19"/>
+    <hbox id="left-right" left="12" right="9" width="15" height="6"
+                          expectedleft="12" expectedtop="0" expectedright="*9" expectedbottom="*0"
+                          stackwidth="36" stackheight="6"/>
+    <hbox id="start-right" start="12" right="9" width="15" height="6"
+                           expectedleft="12" expectedtop="0" expectedright="*9" expectedbottom="*0"
+                           stackwidth="36" stackheight="6"/>
+    <hbox id="left-end" start="12" end="9" width="15" height="6"
+                        expectedleft="12" expectedtop="0" expectedright="*9" expectedbottom="*0"
+                        stackwidth="36" stackheight="6"/>
+    <hbox id="start-end" start="12" end="9" width="15" height="6"
+                         expectedleft="12" expectedtop="0" expectedright="*9" expectedbottom="*0"
+                         stackwidth="36" stackheight="6"/>
+    <hbox id="top-bottom" top="20" bottom="39" width="15" height="6"
+                          expectedleft="0" expectedtop="20" expectedright="*0" expectedbottom="*39"
+                          stackwidth="15" stackheight="65"/>
+    <hbox id="left-right-top-bottom" style="left: 5px; top: 5px; right: 8px; bottom: 8px;"
+                                     left="16" top="20" right="20" bottom="35" width="7" height="8"
+                                     expectedleft="16" expectedtop="20" expectedright="*20" expectedbottom="*35"
+                                     stackwidth="43" stackheight="63"/>
+    <hbox id="start-right-top-bottom" style="left: 5px; top: 5px; right: 8px; bottom: 8px;"
+                                      start="16" top="20" right="20" bottom="35" width="7" height="8"
+                                      expectedleft="16" expectedtop="20" expectedright="*20" expectedbottom="*35"
+                                      stackwidth="43" stackheight="63"/>
+    <hbox id="left-end-top-bottom" style="left: 5px; top: 5px; right: 8px; bottom: 8px;"
+                                   left="16" top="20" end="20" bottom="35" width="7" height="8"
+                                   expectedleft="16" expectedtop="20" expectedright="*20" expectedbottom="*35"
+                                   stackwidth="43" stackheight="63"/>
+    <hbox id="start-end-top-bottom" style="left: 5px; top: 5px; right: 8px; bottom: 8px;"
+                                    start="16" top="20" end="20" bottom="35" width="7" height="8"
+                                    expectedleft="16" expectedtop="20" expectedright="*20" expectedbottom="*35"
+                                    stackwidth="43" stackheight="63"/>
+    <hbox id="left-right-top-bottom-nosize" left="16" top="20" right="20" bottom="35"
+                                            expectedleft="16" expectedtop="20" expectedright="*20" expectedbottom="*35"
+                                            stackwidth="36" stackheight="55"/>
+    <hbox id="start-right-top-bottom-nosize" start="16" top="20" right="20" bottom="35"
+                                             expectedleft="16" expectedtop="20" expectedright="*20" expectedbottom="*35"
+                                             stackwidth="36" stackheight="55"/>
+    <hbox id="left-end-top-bottom-nosize" left="16" top="20" end="20" bottom="35"
+                                          expectedleft="16" expectedtop="20" expectedright="*20" expectedbottom="*35"
+                                          stackwidth="36" stackheight="55"/>
+    <hbox id="start-end-top-bottom-nosize" start="16" top="20" end="20" bottom="35"
+                                           expectedleft="16" expectedtop="20" expectedright="*20" expectedbottom="*35"
+                                           stackwidth="36" stackheight="55"/>
+    <hbox id="none" width="10" height="12" expectedleft="0" expectedtop="0" expectedright="*0" expectedbottom="*0"
+                    stackwidth="10" stackheight="12"/>
+    <hbox id="none-nosize" expectedleft="0" expectedtop="0" expectedright="*0" expectedbottom="*0"
+                           stackwidth="0" stackheight="0"/>
+    <hbox id="style-left-right-top-bottom"
+          style="left: 17px; top: 20px;" right="20" bottom="35" width="7" height="8"
+          expectedleft="*27" expectedtop="*43" expectedright="*20" expectedbottom="*35"
+          stackwidth="27" stackheight="43"/>
+    <hbox id="style-left-right-top-bottom-nosize"
+          style="left: 16px; top: 20px; right: 20px; bottom: 35px;"
+          expectedleft="0" expectedtop="0" expectedright="*0" expectedbottom="*0"
+          stackwidth="0" stackheight="0"/>
+    <hbox id="left-large-right" left="20" right="1000" height="6"
+          expectedleft="20" expectedtop="0" expectedright="20" expectedbottom="*0"
+          stackwidth="1020" stackheight="6"/>
+    <hbox id="left-top-with-margin" left="8" top="17" width="20" height="24"
+          style="margin: 1px 2px 3px 4px;"
+          expectedleft="12" expectedtop="18" expectedright="32" expectedbottom="42"
+          stackwidth="34" stackheight="45"/>
+    <hbox id="right-bottom-with-margin" right="6" bottom="15" width="10" height="14"
+          style="margin: 1px 2px 3px 4px;"
+          expectedleft="*18" expectedtop="*32" expectedright="*8" expectedbottom="*18"
+          stackwidth="22" stackheight="33"/>
+    <hbox id="left-top-right-bottom-with-margin" left="14" right="6" top="8" bottom="15" width="10" height="14"
+          style="margin: 1px 2px 3px 4px;"
+          expectedleft="18" expectedtop="9" expectedright="*8" expectedbottom="*18"
+          stackwidth="36" stackheight="41"/>
+    <hbox id="none-with-margin"
+          style="margin: 1px 2px 3px 4px;"
+          expectedleft="4" expectedtop="1" expectedright="*2" expectedbottom="*3"
+          stackwidth="6" stackheight="4"/>
+  </stack>
+
+  <stack id="stack-with-size" width="12" height="14">
+    <hbox id="left-top-with-stack-size" left="10" top="12" width="20" height="24"
+                                        expectedleft="10" expectedtop="12" expectedright="30" expectedbottom="36"/>
+  </stack>
+
+  <stack id="stack-with-start-end" width="30">
+    <hbox id="start-with-start-end" start="10" top="12" width="20" height="24"
+                                    expectedstart="10" expectedend="30"/>
+    <hbox id="end-width-start-end" end="5" top="12" width="20" height="24"
+                                   expectedstart="5" expectedend="25"/>
+    <hbox id="start-end-width-start-end" start="12" end="9" width="20" top="12" height="24"
+                                         expectedstart="12" expectedend="21"/>
+  </stack>
+
+  <stack id="stack-with-border"
+         style="border-left: 4px solid black; border-top: 2px solid black; border-right: 1px solid black; border-bottom: 3px solid black;">
+    <hbox id="left-top-with-border" left="10" top="14" width="20" height="24"
+                                    expectedleft="14" expectedtop="16" expectedright="34" expectedbottom="40"/>
+    <hbox id="start-top-with-border" start="10" top="14" width="20" height="24"
+                                     expectedleft="14" expectedtop="16" expectedright="34" expectedbottom="40"/>
+    <hbox id="right-bottom-with-border" right="5" bottom="8" width="6" height="10"
+                                        expectedleft="*12" expectedtop="*21" expectedright="*6" expectedbottom="*11"/>
+    <hbox id="end-bottom-with-border" end="5" bottom="8" width="6" height="10"
+                                      expectedleft="*12" expectedtop="*21" expectedright="*6" expectedbottom="*11"/>
+    <hbox id="left-top-right-bottom-with-border" left="12" right="5" top="18" bottom="8"
+          expectedleft="16" expectedtop="20" expectedright="*6" expectedbottom="*11"/>
+    <hbox id="start-top-right-bottom-with-border" start="12" right="5" top="18" bottom="8"
+          expectedleft="16" expectedtop="20" expectedright="*6" expectedbottom="*11"/>
+    <hbox id="left-top-end-bottom-with-border" left="12" end="5" top="18" bottom="8"
+          expectedleft="16" expectedtop="20" expectedright="*6" expectedbottom="*11"/>
+    <hbox id="start-top-end-bottom-with-border" start="12" end="5" top="18" bottom="8"
+          expectedleft="16" expectedtop="20" expectedright="*6" expectedbottom="*11"/>
+    <hbox id="none-with-with-border"
+          expectedleft="4" expectedtop="2" expectedright="*1" expectedbottom="*3"/>
+  </stack>
+
+  <stack id="stack-dyn"/>
+  <stack id="stack-dyn-sized" width="12" height="14"/>
+
+  <body xmlns="http://www.w3.org/1999/xhtml"/>
+
+  <script><![CDATA[
+    SimpleTest.waitForExplicitFinish();
+
+    var stackRect;
+    var dynStack;
+
+    function compareSide(child, actual, side, dyn, direction)
+    {
+      var clientRect = child.getBoundingClientRect();
+      var vertical = (side == "top" || side == "bottom");
+      var expectedval = child.getAttribute("expected" + side);
+      if (expectedval.indexOf("*") == 0)
+        expectedval = (vertical ? stackRect.bottom : stackRect.right) - Number(expectedval.substring(1));
+      else if (direction == "rtl")
+        expectedval = (vertical ? stackRect.top : -stackRect.width + clientRect.right + clientRect.left) + Number(expectedval);
+      else
+        expectedval = (vertical ? stackRect.top : stackRect.left) + Number(expectedval);
+
+      is(+actual, expectedval, child.id + " " + side + (dyn ? " dynamic" : ""));
+    }
+
+    function runTest()
+    {
+      runTestForStack("stack", false);
+      runTestForStack("stack-with-size", false);
+      runTestForStartEndAttributes("stack-with-start-end", "ltr");
+      runTestForStartEndAttributes("stack-with-start-end", "rtl");
+
+      var stackWithSize = $("stack-with-size");
+
+      var sizedStackRect = stackWithSize.getBoundingClientRect();
+      is(sizedStackRect.width, 30, "stack size stretched width");
+      is(sizedStackRect.height, 36, "stack size stretched height");
+
+      // set -moz-stack-sizing: ignore and ensure that the stack does not grow
+      // to include the child
+      var item = $("left-top-with-stack-size");
+      item.style.MozStackSizing = "ignore";
+      var parent = item.parentNode;
+      parent.removeChild(item);
+      parent.appendChild(item);
+
+      sizedStackRect = stackWithSize.getBoundingClientRect();
+      is(sizedStackRect.width, 12, "stack size not stretched width");
+      is(sizedStackRect.height, 14, "stack size not stretched height");
+
+      testPositionChanges(stackWithSize, true);
+      item.style.MozStackSizing = "";
+      testPositionChanges(stackWithSize, false);
+
+      // now test adding stack children dynamically to ensure that
+      // the size of the stack adjusts accordingly
+      dynStack = $("stack-dyn");
+      runTestForStack("stack", true);
+
+      SimpleTest.finish();
+    }
+
+    function runTestForStartEndAttributes(stackid, aDirection)
+    {
+      // Change the direction of the layout to RTL to ensure start/end are
+      // working as expected
+      var stack = $(stackid);
+      stack.style.direction = aDirection;
+
+      var stackRect = stack.getBoundingClientRect();
+      var children = stack.childNodes;
+      for (var c = children.length - 1; c >= 0; c--) {
+        var child = children[c];
+      
+        // do tests only for elements that have a rtl-enabled mode
+        if (!child.hasAttribute("start") && !child.hasAttribute("end"))
+          continue;
+
+        var childrect = child.getBoundingClientRect();
+        compareSide(child, childrect.right, "end", false, aDirection);
+        compareSide(child, childrect.left, "start", false, aDirection);
+      }
+
+      // Reset the direction
+      stack.style.direction = "ltr";
+    }
+
+    function runTestForStack(stackid, dyn)
+    {
+      var stack = $(stackid);
+      if (!dyn)
+        stackRect = stack.getBoundingClientRect();
+      var children = stack.childNodes;
+      for (var c = children.length - 1; c >= 0; c--) {
+        var child = children[c];
+        if (dyn) {
+          // for dynamic tests, get the size after appending the child as the
+          // stack size will be effected by it
+          dynStack.appendChild(child);
+          stackRect = dynStack.getBoundingClientRect();
+          is(String(stackRect.width), child.getAttribute("stackwidth"), child.id + " stack width" + (dyn ? " dynamic" : ""));
+          is(String(stackRect.height), child.getAttribute("stackheight"), child.id + " stack height" + (dyn ? " dynamic" : ""));
+        }
+
+        var childrect = child.getBoundingClientRect();
+        compareSide(child, childrect.left, "left", dyn);
+        compareSide(child, childrect.top, "top", dyn);
+        compareSide(child, childrect.right, "right", dyn);
+        compareSide(child, childrect.bottom, "bottom", dyn);
+        if (dyn)
+          dynStack.removeChild(child);
+      }
+    }
+
+    function testPositionChanges(stack, ignoreStackSizing)
+    {
+      var add = ignoreStackSizing ? " ignore stack sizing" : "";
+
+      // ensure that changing left/top/right/bottom/start/end works
+      var stackchild = document.getElementById("left-top-with-stack-size");
+      stackchild.left = 18;
+      is(stackchild.getBoundingClientRect().left, stack.getBoundingClientRect().left + 18, "left changed" + add);
+      is(stack.getBoundingClientRect().width, ignoreStackSizing ? 12 : 38, "left changed stack width" + add);
+
+      stackchild.left = "";
+      stackchild.setAttribute("start", "19");
+      is(stackchild.getBoundingClientRect().left, stack.getBoundingClientRect().left + 19, "left changed" + add);
+      is(stack.getBoundingClientRect().width, ignoreStackSizing ? 12 : 39, "left changed stack width" + add);
+      stackchild.removeAttribute("start");
+      stackchild.left = 18;
+
+      stackchild.top = 22;
+      is(stackchild.getBoundingClientRect().top, stack.getBoundingClientRect().top + 22, "top changed" + add);
+      is(stack.getBoundingClientRect().height, ignoreStackSizing ? 14 : 46, "left changed stack height" + add);
+
+      stackchild.setAttribute("right", "6");
+      is(stackchild.getBoundingClientRect().right, stack.getBoundingClientRect().left + 18, "right changed" + add);
+      // the width is only 12 pixels in ignoreStackSizing mode, so don't check the offset
+      // from the right edge in this case
+      if (!ignoreStackSizing)
+        is(stackchild.getBoundingClientRect().right, stack.getBoundingClientRect().right - 6,
+           "right changed from right edge" + add);
+      is(stack.getBoundingClientRect().width, ignoreStackSizing ? 12 : 24, "right changed stack width" + add);
+
+      stackchild.removeAttribute("right");
+      stackchild.setAttribute("end", "7");
+      is(stackchild.getBoundingClientRect().right, stack.getBoundingClientRect().left + 18, "right changed" + add);
+      // the width is only 12 pixels in ignoreStackSizing mode, so don't check the offset
+      // from the right edge in this case
+      if (!ignoreStackSizing)
+        is(stackchild.getBoundingClientRect().right, stack.getBoundingClientRect().right - 7,
+           "right changed from right edge" + add);
+      is(stack.getBoundingClientRect().width, ignoreStackSizing ? 12 : 25, "right changed stack width" + add);
+      stackchild.removeAttribute("end");
+      stackchild.setAttribute("right", "6");
+
+      stackchild.setAttribute("bottom", "9");
+      is(stackchild.getBoundingClientRect().bottom, stack.getBoundingClientRect().top + 22, "bottom changed" + add);
+      is(stack.getBoundingClientRect().height, ignoreStackSizing ? 14 : 31, "bottom changed stack height" + add);
+      if (!ignoreStackSizing)
+        is(stackchild.getBoundingClientRect().bottom, stack.getBoundingClientRect().bottom - 9,
+           "right changed from bottom edge" + add);
+
+      stackchild.left = "";
+      is(stackchild.getBoundingClientRect().right, stack.getBoundingClientRect().right - 6, "right changed" + add);
+      is(stack.getBoundingClientRect().width, ignoreStackSizing ? 12 : 26, "right changed no left stack width" + add);
+
+      stackchild.removeAttribute("right");
+      is(stackchild.getBoundingClientRect().right, stack.getBoundingClientRect().right, "right cleared" + add);
+      is(stack.getBoundingClientRect().width, 12, "right cleared stack height" + add);
+
+      // reset the values
+      stackchild.removeAttribute("bottom");
+      stackchild.left = 10;
+      stackchild.top = 12;
+    }
+
+
+  ]]></script>
+</window>
diff --git a/layout/xul/test/test_submenuClose.xul b/layout/xul/test/test_submenuClose.xul
new file mode 100644
index 0000000000..907736d999
--- /dev/null
+++ b/layout/xul/test/test_submenuClose.xul
@@ -0,0 +1,91 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1181560
+-->
+<window title="Mozilla Bug 1181560"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="SimpleTest.waitForFocus(nextTest, window)">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1181560"
+     target="_blank">Mozilla Bug 1181560</a>
+  </body>
+
+  <vbox>
+    <menubar>
+      <menu id="menu" label="MyMenu">
+        <menupopup>
+          <menuitem label="A"/>
+          <menu id="b" label="B">
+            <menupopup>
+              <menuitem label="B1"/>
+            </menupopup>
+          </menu>
+          <menu id="c" label="C">
+            <menupopup>
+              <menuitem label="C1"/>
+            </menupopup>
+          </menu>
+        </menupopup>
+      </menu>
+    </menubar>
+  </vbox>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+  /** Test for Bug 1181560 **/
+  SimpleTest.waitForExplicitFinish();
+
+  let menuB, menuC, mainMenu, menuBOpen, menuCOpen;
+  let menuBOpenCount = 0;
+
+  function handleBOpens() {
+    menuBOpenCount++;
+    menuBOpen = true;
+    ok(!menuCOpen, "Menu C should not be open when menu B has opened");
+    if (menuBOpenCount >= 2) {
+      SimpleTest.finish();
+      return;
+    }
+    sendKey("LEFT", window);
+    sendKey("DOWN", window);
+    sendKey("RIGHT", window);
+  }
+
+  function handleBCloses() {
+    menuBOpen = false;
+  }
+
+  function handleCOpens() {
+    menuCOpen = true;
+    ok(!menuBOpen, "Menu B should not be open when menu C has opened");
+    synthesizeMouseAtCenter(menuB, {}, window);
+  }
+
+  function handleCCloses() {
+    menuCOpen = false;
+  }
+
+  function nextTest(e) {
+    mainMenu = document.getElementById("menu");
+    menuB = document.getElementById("b");
+    menuC = document.getElementById("c");
+    menuB.firstChild.addEventListener("popupshown", handleBOpens, false);
+    menuB.firstChild.addEventListener("popuphidden", handleBCloses, false);
+    menuC.firstChild.addEventListener("popupshown", handleCOpens, false);
+    menuC.firstChild.addEventListener("popuphidden", handleCCloses, false);
+    mainMenu.addEventListener("popupshown", ev => {
+      synthesizeMouseAtCenter(menuB, {}, window);
+    });
+    mainMenu.open = true;
+  }
+  ]]>
+  </script>
+</window>
diff --git a/layout/xul/test/test_windowminmaxsize.xul b/layout/xul/test/test_windowminmaxsize.xul
new file mode 100644
index 0000000000..5909039cf5
--- /dev/null
+++ b/layout/xul/test/test_windowminmaxsize.xul
@@ -0,0 +1,245 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+
+<window title="Window Minimum and Maximum Size Tests" onload="nextTest()"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+  <script type="application/javascript" 
+          src="chrome://mochikit/content/MochiKit/packed.js"/>
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+
+<panel id="panel" onpopupshown="doPanelTest(this)" onpopuphidden="nextPopupTest(this)"
+       align="start" pack="start" style="-moz-appearance: none; margin: 0; border: 0; padding: 0;">
+  <resizer id="popupresizer" dir="bottomright" flex="1" width="60" height="60"
+           style="-moz-appearance: none; margin: 0; border: 0; padding: 0;"/>
+</panel>
+
+<script>
+<![CDATA[
+
+SimpleTest.waitForExplicitFinish();
+
+var gTestId = -1;
+
+var prefix = "data:application/vnd.mozilla.xul+xml,<?xml-stylesheet href='chrome://global/skin' type='text/css'?><window " +
+             "xmlns='http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul' " +
+             "align='start' pack='start' style='-moz-appearance: none; margin: 0; padding: 0; border: 0; ";
+var suffix = "><resizer dir='bottomright' flex='1' width='150' height='150' style='-moz-appearance: none; margin: 0; border: 0; padding: 0;'/></window>";
+var titledpanel = "<panel noautohide='true' titlebar='normal' minwidth='120' minheight='140'/><label value='Test'/>";
+
+// width and height in the tests below specify the expected size of the window.
+// note, win8 has a minimum inner window size of around 122 pixels. Don't go below this on min-width tests.
+var tests = [
+  { testname: "unconstrained",
+    style: "", attrs: "",
+    width: 150, height: 150 },
+  { testname: "constraint min style",
+    style: "min-width: 180px; min-height: 210px;", attrs: "",
+    width: 180, height: 210 },
+  { testname: "constraint max style",
+    style: "max-width: 125px; max-height: 140px;", attrs: "",
+    width: 125, height: 140 },
+  { testname: "constraint min attributes",
+    style: "", attrs: "minwidth='240' minheight='220'",
+    width: 240, height: 220 },
+  { testname: "constraint min attributes with width and height set",
+    style: "", attrs: "width='190' height='220' minwidth='215' minheight='235'",
+    width: 215, height: 235 },
+  { testname: "constraint max attributes",
+    style: "", attrs: "maxwidth='125' maxheight='95'",
+    width: 125, height: 95 },
+  // this gets the inner width as <window minwidth='210'> makes the box 210 pixels wide
+  { testname: "constraint min width attribute only",
+    style: "", attrs: "minwidth='210'",
+    width: 210, height: 150 },
+  { testname: "constraint max width attribute only",
+    style: "", attrs: "maxwidth='128'",
+    width: 128, height: 150 },
+  { testname: "constraint max width attribute with minheight",
+    style: "", attrs: "maxwidth='195' width='230' height='120' minheight='180'",
+    width: 195, height: 180 },
+  { testname: "constraint minwidth, minheight, maxwidth and maxheight set",
+    style: "", attrs: "minwidth='120' maxwidth='480' minheight='110' maxheight='470'",
+    width: 150, height: 150, last: true }
+];
+
+var popupTests = [
+  { testname: "popup unconstrained",
+    width: 60, height: 60
+  },
+  { testname: "popup with minimum size",
+    minwidth: 150, minheight: 180,
+    width: 150, height: 180
+  },
+  { testname: "popup with maximum size",
+    maxwidth: 50, maxheight: 45,
+    width: 50, height: 45,
+  },
+  { testname: "popup with minimum and size",
+    minwidth: 80, minheight: 70, maxwidth: 250, maxheight: 220,
+    width: 80, height: 70, last: true
+  }
+];
+
+function nextTest()
+{
+  // Run through each of the tests above by opening a simple window with
+  // the attributes or style defined for that test. The comparisons will be
+  // done by windowOpened. gTestId holds the index into the tests array.
+  if (++gTestId >= tests.length) {
+    // Now do the popup tests
+    gTestId = -1;
+    SimpleTest.waitForFocus(function () { nextPopupTest(document.getElementById("panel")) } );
+  }
+  else {
+    tests[gTestId].window = window.open(prefix + tests[gTestId].style + "' " + tests[gTestId].attrs + suffix, "_blank", "chrome,resizable=yes");
+    SimpleTest.waitForFocus(windowOpened, tests[gTestId].window);
+  }
+}
+
+function windowOpened(otherWindow)
+{
+  // Check the width and the width plus one due to bug 696746.
+  ok(otherWindow.innerWidth == tests[gTestId].width ||
+     otherWindow.innerWidth == tests[gTestId].width + 1,
+    tests[gTestId].testname + " width of " + otherWindow.innerWidth + " matches " + tests[gTestId].width);
+  is(otherWindow.innerHeight, tests[gTestId].height, tests[gTestId].testname + " height");
+
+  // On the last test, try moving the resizer to a size larger than the maximum
+  // and smaller than the minimum. This test is only done on Mac as the other
+  // platforms use native resizing.
+  if ('last' in tests[gTestId] && (navigator.platform.indexOf("Mac") == 0)) {
+    var resizer = otherWindow.document.documentElement.firstChild;
+    synthesizeMouse(resizer, 4, 4, { type:"mousedown" }, otherWindow);
+    synthesizeMouse(resizer, 800, 800, { type:"mousemove" }, otherWindow);
+    is(otherWindow.innerWidth, 480, "Width after maximum resize");
+    is(otherWindow.innerHeight, 470, "Height after maximum resize");
+
+    synthesizeMouse(resizer, -100, -100, { type:"mousemove" }, otherWindow);
+    is(otherWindow.innerWidth, 120, "Width after minimum resize");
+    is(otherWindow.innerHeight, 110, "Height after minimum resize");
+
+    synthesizeMouse(resizer, 4, 4, { type:"mouseup" }, otherWindow);
+
+    // Change the minimum and maximum size and try resizing the window again.
+    otherWindow.document.documentElement.minWidth = 140;
+    otherWindow.document.documentElement.minHeight = 130;
+    otherWindow.document.documentElement.maxWidth = 380;
+    otherWindow.document.documentElement.maxHeight = 360;
+
+    synthesizeMouse(resizer, 4, 4, { type:"mousedown" }, otherWindow);
+    synthesizeMouse(resizer, 800, 800, { type:"mousemove" }, otherWindow);
+    is(otherWindow.innerWidth, 380, "Width after changed maximum resize");
+    is(otherWindow.innerHeight, 360, "Height after changed maximum resize");
+
+    synthesizeMouse(resizer, -100, -100, { type:"mousemove" }, otherWindow);
+    is(otherWindow.innerWidth, 140, "Width after changed minimum resize");
+    is(otherWindow.innerHeight, 130, "Height after changed minimum resize");
+
+    synthesizeMouse(resizer, 4, 4, { type:"mouseup" }, otherWindow);
+  }
+
+  otherWindow.close();
+  nextTest();
+}
+
+function doPanelTest(panel)
+{
+  var rect = panel.getBoundingClientRect();
+  is(rect.width, popupTests[gTestId].width, popupTests[gTestId].testname + " width");
+  is(rect.height, popupTests[gTestId].height, popupTests[gTestId].testname + " height");
+
+  if ('last' in popupTests[gTestId]) {
+    var resizer = document.getElementById("popupresizer");
+    synthesizeMouse(resizer, 4, 4, { type:"mousedown" });
+    synthesizeMouse(resizer, 800, 800, { type:"mousemove" });
+
+    rect = panel.getBoundingClientRect();
+    is(rect.width, 250, "Popup width after maximum resize");
+    is(rect.height, 220, "Popup height after maximum resize");
+
+    synthesizeMouse(resizer, -100, -100, { type:"mousemove" });
+
+    rect = panel.getBoundingClientRect();
+    is(rect.width, 80, "Popup width after minimum resize");
+    is(rect.height, 70, "Popup height after minimum resize");
+
+    synthesizeMouse(resizer, 4, 4, { type:"mouseup" });
+  }
+
+  panel.hidePopup();
+}
+
+function nextPopupTest(panel)
+{
+  if (++gTestId >= popupTests.length) {
+    // Next, check a panel that has a titlebar to ensure that it is accounted for
+    // properly in the size.
+    var titledPanelWindow = window.open(prefix + "'>" + titledpanel + "</window>", "_blank", "chrome,resizable=yes");
+    SimpleTest.waitForFocus(titledPanelWindowOpened, titledPanelWindow);
+  }
+  else {
+    function setattr(attr) {
+      if (attr in popupTests[gTestId])
+        panel.setAttribute(attr, popupTests[gTestId][attr]);
+      else
+        panel.removeAttribute(attr);
+    }
+    setattr("minwidth");
+    setattr("minheight");
+    setattr("maxwidth");
+    setattr("maxheight");
+
+    // Remove the flexibility as it causes the resizer to not shrink down
+    // when resizing.
+    if ("last" in popupTests[gTestId])
+      document.getElementById("popupresizer").removeAttribute("flex");
+
+    // Prevent event loop starvation as a result of popup events being
+    // synchronous. See bug 1131576.
+    SimpleTest.executeSoon(() => {
+      // Non-chrome shells require focus to open a popup.
+      SimpleTest.waitForFocus(() => { panel.openPopup() });
+    });
+  }
+}
+
+function titledPanelWindowOpened(panelwindow)
+{
+  var panel = panelwindow.document.documentElement.firstChild;
+  panel.openPopup();
+  panel.addEventListener("popupshown", () => doTitledPanelTest(panel), false);
+  panel.addEventListener("popuphidden", () => done(panelwindow), false);
+}
+
+function doTitledPanelTest(panel)
+{
+  var rect = panel.getBoundingClientRect();
+  is(rect.width, 120, "panel with titlebar width");
+  is(rect.height, 140, "panel with titlebar height");
+  panel.hidePopup();
+}
+
+function done(panelwindow)
+{
+  panelwindow.close();
+  SimpleTest.finish();
+}
+
+]]>
+</script>
+
+<body xmlns="http://www.w3.org/1999/xhtml">
+<p id="display">
+</p>
+<div id="content" style="display: none">
+</div>
+<pre id="test">
+</pre>
+</body>
+
+</window>
diff --git a/layout/xul/test/window_resizer.xul b/layout/xul/test/window_resizer.xul
new file mode 100644
index 0000000000..4e349d125c
--- /dev/null
+++ b/layout/xul/test/window_resizer.xul
@@ -0,0 +1,113 @@
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+    screenX="200" screenY="200" width="300" height="300"
+	onload="setTimeout(doTest, 0)">
+<script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+<script><![CDATA[
+var is = window.opener.SimpleTest.is;
+
+function doTest() {
+  // from test_resizer.xul
+  var expectX = 200;
+  var expectY = 200;
+  var expectXMost = 500;
+  var expectYMost = 500;
+  var screenScale = expectX/window.screenX;
+  var root = document.documentElement;
+
+  var oldScreenX = window.screenX;
+  var oldScreenY = window.screenY;
+  var oldWidth = window.outerWidth;
+  var oldHeight = window.outerHeight;
+
+  function testResizer(dx, dy) {
+    var offset = 20;
+    var scale = 5;
+    // target the centre of the resizer
+    var offsetX = window.innerWidth/2 + (window.innerWidth/3)*dx;
+    var offsetY = window.innerHeight/2 + (window.innerHeight/3)*dy;
+
+    for (var mouseX = -1; mouseX <= 1; ++mouseX) {
+      for (var mouseY = -1; mouseY <= 1; ++mouseY) {
+        var newExpectX = expectX;
+        var newExpectXMost = expectXMost;
+        var newExpectY = expectY;
+        var newExpectYMost = expectYMost;
+        if (dx < 0) {
+          newExpectX += mouseX*scale;
+        } else if (dx > 0) {
+          newExpectXMost += mouseX*scale;
+        }
+        if (dy < 0) {
+          newExpectY += mouseY*scale;
+        } else if (dy > 0) {
+          newExpectYMost += mouseY*scale;
+        }
+
+        synthesizeMouse(root, offsetX, offsetY, { type:"mousedown" });
+        synthesizeMouse(root, offsetX + mouseX*scale, offsetY + mouseY*scale, { type:"mousemove" });
+        is(window.screenX*screenScale, newExpectX,
+           "Bad x for " + dx + "," + dy + " moving " + mouseX + "," + mouseY);
+        is(window.screenY*screenScale, newExpectY,
+           "Bad y for " + dx + "," + dy + " moving " + mouseX + "," + mouseY);
+        is(window.outerWidth, newExpectXMost - newExpectX,
+           "Bad width for " + dx + "," + dy + " moving " + mouseX + "," + mouseY);
+        is(window.outerHeight, newExpectYMost - newExpectY,
+           "Bad height for " + dx + "," + dy + " moving " + mouseX + "," + mouseY);
+
+        // move it back before we release! Adjust for any window movement
+        synthesizeMouse(root, offsetX - (newExpectX - expectX),
+                              offsetY - (newExpectY - expectY), { type:"mousemove" });
+        synthesizeMouse(root, offsetX, offsetY, { type:"mouseup" });
+      }
+    }
+  }
+
+  testResizer(-1, -1);
+  testResizer(-1, 0);
+  testResizer(-1, 1);
+  testResizer(0, -1);
+  testResizer(0, 1);
+  testResizer(1, -1);
+  testResizer(1, 0);
+  testResizer(1, 1);
+
+  var resizers = document.getElementsByTagName("resizer");
+  Array.forEach(resizers, function (element) {
+    is(getComputedStyle(element, "").cursor,
+       element.getAttribute("expectedcursor"),
+       "cursor for " + element.dir);
+  });
+
+  // now check the cursors in rtl. The bottomend resizer
+  // should be reversed
+  document.getElementById("bottomend").setAttribute("rtl", "true");
+  Array.forEach(resizers, function (element) {
+    is(getComputedStyle(element, "").cursor,
+       element.dir == "bottomend" ? "sw-resize" :
+         element.getAttribute("expectedcursor"),
+       "cursor for " + element.dir);
+  });
+
+  window.close();
+  window.opener.lastResizerTest();
+}
+]]></script>
+	<hbox id="container" flex="1">
+		<vbox flex="1">
+			<resizer dir="topleft" expectedcursor="nw-resize" flex="1"/>
+			<resizer dir="left" expectedcursor="ew-resize" flex="1"/>
+			<resizer dir="bottomleft" expectedcursor="sw-resize" flex="1"/>
+		</vbox>
+		<vbox flex="1">
+			<resizer dir="top" expectedcursor="ns-resize" flex="1"/>
+			<resizer id="bottomend" dir="bottomend" expectedcursor="se-resize" flex="1"/>
+			<resizer dir="bottom" expectedcursor="ns-resize" flex="1"/>
+		</vbox>
+		<vbox flex="1">
+			<resizer dir="topright" expectedcursor="ne-resize" flex="1"/>
+			<resizer dir="right" expectedcursor="ew-resize" flex="1"/>
+			<resizer dir="bottomright" expectedcursor="se-resize" flex="1"/>
+		</vbox>
+	</hbox>
+</window>
diff --git a/layout/xul/test/window_resizer_element.xul b/layout/xul/test/window_resizer_element.xul
new file mode 100644
index 0000000000..b0c58d1a19
--- /dev/null
+++ b/layout/xul/test/window_resizer_element.xul
@@ -0,0 +1,188 @@
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        align="start">
+<script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+<script><![CDATA[
+var is = window.opener.SimpleTest.is;
+window.onerror = window.opener.onerror;
+
+const anchorPositions =
+  [ "before_start", "before_end", "after_start", "after_end",
+    "start_before", "start_after", "end_before", "end_after", "overlap", "screen"];
+var currentPosition;
+
+function testResizer(resizerid, noShrink, hResize, vResize, testid)
+{
+  var rect = document.getElementById(resizerid + "-container").getBoundingClientRect();
+  var resizer = document.getElementById(resizerid);
+  var resizerrect = resizer.getBoundingClientRect();
+
+  var originalX = resizerrect.left;
+  var originalY = resizerrect.top;
+
+  const scale = 20;
+  for (var mouseX = -1; mouseX <= 1; ++mouseX) {
+    for (var mouseY = -1; mouseY <= 1; ++mouseY) {
+      var expectedWidth = rect.width + hResize * mouseX * scale;
+      var expectedHeight = rect.height + vResize * mouseY * scale;
+
+      if (noShrink) {
+        if (mouseX == -1)
+          expectedWidth = rect.width;
+        if (mouseY == -1)
+          expectedHeight = rect.height;
+      }
+
+      synthesizeMouse(document.documentElement, originalX + 5, originalY + 5, { type:"mousedown" });
+      synthesizeMouse(document.documentElement, originalX + 5 + mouseX * scale,
+                      originalY + 5 + mouseY * scale, { type:"mousemove" });
+
+      var newrect = document.getElementById(resizerid + "-container").getBoundingClientRect();
+      is(Math.round(newrect.width), Math.round(expectedWidth), "resize element " + resizerid +
+         " " + testid + " width moving " + mouseX + "," + mouseY + ",,," + hResize);
+      is(Math.round(newrect.height), Math.round(expectedHeight), "resize element " + resizerid +
+         " " + testid + " height moving " + mouseX + "," + mouseY);
+      // release
+      synthesizeMouse(document.documentElement, originalX + 5 + mouseX * scale,
+                      originalY + 5 + mouseY * scale, { type:"mouseup" });
+      // return to the original size
+      synthesizeMouse(document.documentElement, originalX + 5 + mouseX * scale,
+                      originalY + 5 + mouseY * scale, { type:"dblclick" });
+      var newrect = document.getElementById(resizerid + "-container").getBoundingClientRect();
+      is(Math.round(newrect.width), Math.round(rect.width), "resize element " + resizerid +
+         " " + testid + " doubleclicking to restore original size");
+      is(Math.round(newrect.height), Math.round(rect.height), "resize element " + resizerid +
+         " " + testid + " doubleclicking to restore original size");
+    }
+  }
+}
+
+function doTest() {
+  // first, check if a resizer with a element attribute set to an element that
+  // does not exist does not cause a problem
+  var resizer = document.getElementById("notfound");
+  synthesizeMouse(resizer, 5, 5, { type:"mousedown" });
+  synthesizeMouse(resizer, 10, 10, { type:"mousemove" });
+  synthesizeMouse(resizer, 5, 5, { type:"mouseup" });
+
+  testResizer("outside", true, 1, 1, "");
+  testResizer("html", true, 1, 1, "");
+  testResizer("inside", true, 1, 1, "");
+  testResizer("inside-large", false, 1, 1, "");
+  testResizer("inside-with-border", true, 1, 1, "");
+
+  document.getElementById("inside-popup-container").
+    openPopupAtScreen(Math.ceil(window.mozInnerScreenX) + 100, Math.ceil(window.mozInnerScreenY) + 100);
+}
+
+function popupShown(event)
+{
+  testResizer("inside-popup", false, 1, 1, "");
+  document.getElementById("inside-popup-container").id = "outside-popup-container";
+  testResizer("outside-popup", false, 1, 1, "");
+
+  var resizerrect = document.getElementById("inside-popup").getBoundingClientRect();
+  synthesizeMouse(document.documentElement, resizerrect.left + 5, resizerrect.top + 5, { type:"mousedown" });
+  synthesizeMouse(document.documentElement, resizerrect.left + 2000, resizerrect.top + 2000, { type:"mousemove" });
+
+  var isMac = (navigator.platform.indexOf("Mac") >= 0);
+  var popuprect = document.getElementById("outside-popup-container").getBoundingClientRect();
+  // subtract 3 due to space left for panel dropshadow
+  is(Math.ceil(window.mozInnerScreenX) + popuprect.right,
+     (isMac ? screen.availLeft + screen.availWidth : screen.left + screen.width) - 3, "resized to edge width");
+  is(Math.ceil(window.mozInnerScreenY) + popuprect.bottom,
+     (isMac ? screen.availTop + screen.availHeight : screen.top + screen.height) - 3, "resized to edge height");
+
+  resizerrect = document.getElementById("inside-popup").getBoundingClientRect();
+  synthesizeMouse(document.documentElement, resizerrect.left + 5, resizerrect.top + 5, { type:"mouseup" });
+
+  event.target.hidePopup();
+}
+
+function popupHidden()
+{
+  if (anchorPositions.length == 0) {
+    window.close();
+    window.opener.SimpleTest.finish();
+    return;
+  }
+
+  currentPosition = anchorPositions.shift();
+  var anchor = document.getElementById("anchor");
+  var popup = document.getElementById("anchored-panel-container");
+
+  if (currentPosition == "screen")
+    popup.openPopupAtScreen(window.screenX + 100, window.screenY + 100);
+  else
+    popup.openPopup(anchor, currentPosition);
+}
+
+function anchoredPopupShown(event)
+{
+  var leftAllowed = (currentPosition.indexOf("end_") == -1 && currentPosition.indexOf("_start") == -1);
+  var rightAllowed = (currentPosition.indexOf("start_") == -1 && currentPosition.indexOf("_end") == -1);
+  var topAllowed = (currentPosition.indexOf("after_") == -1 && currentPosition.indexOf("_before") == -1);
+  var bottomAllowed = (currentPosition.indexOf("before_") == -1 && currentPosition.indexOf("_after") == -1);
+
+  if (currentPosition == "overlap") {
+    leftAllowed = topAllowed = false;
+    rightAllowed = bottomAllowed = true;
+  }
+
+  var resizerTypes = [ "topleft", "top", "topright", "left", "right",
+                       "bottomleft", "bottom", "bottomright", "bottomend" ];
+  for (var r = 0; r < resizerTypes.length; r++) {
+    var resizerType = resizerTypes[r];
+    var horiz = 0, vert = 0;
+    if (leftAllowed && resizerType.indexOf("left") >= 0) horiz = -1;
+    else if (rightAllowed && (resizerType.indexOf("right") >= 0 || resizerType == "bottomend")) horiz = 1;
+
+    if (topAllowed && resizerType.indexOf("top") >= 0) vert = -1;
+    else if (bottomAllowed && resizerType.indexOf("bottom") >= 0) vert = 1;
+
+    document.getElementById("anchored-panel").dir = resizerType;
+    testResizer("anchored-panel", false, horiz, vert, currentPosition + " " + resizerType);
+  }
+
+  event.target.hidePopup();
+}
+
+window.opener.SimpleTest.waitForFocus(doTest, window);
+]]></script>
+
+<resizer id="outside" dir="bottomend" element="outside-container"/>
+<resizer id="notfound" dir="bottomend" element="nothing"/>
+<hbox id="outside-container">
+  <hbox minwidth="46" minheight="39"/>
+</hbox>
+<html:div id="html-container" xmlns:html="http://www.w3.org/1999/xhtml">
+  <html:button>One</html:button><html:br/>
+  <resizer id="html" dir="bottomend" element="_parent"/>
+</html:div>
+<hbox id="anchor" align="start" style="margin-left: 100px;">
+  <hbox id="inside-container" align="start">
+    <hbox minwidth="45" minheight="41"/>
+    <resizer id="inside" dir="bottomend" element="_parent"/>
+  </hbox>
+  <hbox id="inside-large-container" width="70" height="70" align="start">
+    <resizer id="inside-large" dir="bottomend" element="_parent"/>
+  </hbox>
+  <hbox id="inside-with-border-container" style="border: 5px solid red; padding: 2px; margin: 2px;" align="start">
+    <hbox minwidth="35" minheight="30"/>
+    <resizer id="inside-with-border" dir="bottomend" element="_parent"/>
+  </hbox>
+</hbox>
+
+<panel id="inside-popup-container" align="start" onpopupshown="popupShown(event)" onpopuphidden="popupHidden()">
+  <resizer id="inside-popup" dir="bottomend"/>
+  <hbox width="50" height="50" flex="1"/>
+</panel>
+<resizer id="outside-popup" dir="bottomend" element="outside-popup-container"/>
+
+<panel id="anchored-panel-container" align="start" onpopupshown="anchoredPopupShown(event)"
+       onpopuphidden="popupHidden()">
+  <hbox width="50" height="50" flex="1"/>
+  <resizer id="anchored-panel" width="20" height="20"/>
+</panel>
+
+</window>
diff --git a/layout/xul/tree/TreeBoxObject.cpp b/layout/xul/tree/TreeBoxObject.cpp
new file mode 100644
index 0000000000..2265d9ee55
--- /dev/null
+++ b/layout/xul/tree/TreeBoxObject.cpp
@@ -0,0 +1,695 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/TreeBoxObject.h"
+#include "nsCOMPtr.h"
+#include "nsIDOMXULElement.h"
+#include "nsIScriptableRegion.h"
+#include "nsIXULTemplateBuilder.h"
+#include "nsTreeContentView.h"
+#include "nsITreeSelection.h"
+#include "ChildIterator.h"
+#include "nsContentUtils.h"
+#include "nsError.h"
+#include "nsTreeBodyFrame.h"
+#include "mozilla/dom/TreeBoxObjectBinding.h"
+#include "nsITreeColumns.h"
+#include "mozilla/dom/DOMRect.h"
+#include "mozilla/dom/BindingUtils.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/ToJSValue.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(TreeBoxObject, BoxObject,
+                                   mView)
+
+NS_IMPL_ADDREF_INHERITED(TreeBoxObject, BoxObject)
+NS_IMPL_RELEASE_INHERITED(TreeBoxObject, BoxObject)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(TreeBoxObject)
+  NS_INTERFACE_MAP_ENTRY(nsITreeBoxObject)
+NS_INTERFACE_MAP_END_INHERITING(BoxObject)
+
+void
+TreeBoxObject::Clear()
+{
+  ClearCachedValues();
+
+  // Drop the view's ref to us.
+  if (mView) {
+    nsCOMPtr<nsITreeSelection> sel;
+    mView->GetSelection(getter_AddRefs(sel));
+    if (sel)
+      sel->SetTree(nullptr);
+    mView->SetTree(nullptr); // Break the circular ref between the view and us.
+  }
+  mView = nullptr;
+
+  BoxObject::Clear();
+}
+
+
+TreeBoxObject::TreeBoxObject()
+  : mTreeBody(nullptr)
+{
+}
+
+TreeBoxObject::~TreeBoxObject()
+{
+}
+
+static nsIContent* FindBodyElement(nsIContent* aParent)
+{
+  mozilla::dom::FlattenedChildIterator iter(aParent);
+  for (nsIContent* content = iter.GetNextChild(); content; content = iter.GetNextChild()) {
+    mozilla::dom::NodeInfo *ni = content->NodeInfo();
+    if (ni->Equals(nsGkAtoms::treechildren, kNameSpaceID_XUL)) {
+      return content;
+    } else if (ni->Equals(nsGkAtoms::tree, kNameSpaceID_XUL)) {
+      // There are nesting tree elements. Only the innermost should
+      // find the treechilren.
+      return nullptr;
+    } else if (content->IsElement() &&
+               !ni->Equals(nsGkAtoms::_template, kNameSpaceID_XUL)) {
+      nsIContent* result = FindBodyElement(content);
+      if (result)
+        return result;
+    }
+  }
+
+  return nullptr;
+}
+
+nsTreeBodyFrame*
+TreeBoxObject::GetTreeBodyFrame(bool aFlushLayout)
+{
+  // Make sure our frames are up to date, and layout as needed.  We
+  // have to do this before checking for our cached mTreeBody, since
+  // it might go away on style flush, and in any case if aFlushLayout
+  // is true we need to make sure to flush no matter what.
+  // XXXbz except that flushing style when we were not asked to flush
+  // layout here breaks things.  See bug 585123.
+  nsIFrame* frame = nullptr;
+  if (aFlushLayout) {
+    frame = GetFrame(aFlushLayout);
+    if (!frame)
+      return nullptr;
+  }
+
+  if (mTreeBody) {
+    // Have one cached already.
+    return mTreeBody;
+  }
+
+  if (!aFlushLayout) {
+    frame = GetFrame(aFlushLayout);
+    if (!frame)
+      return nullptr;
+  }
+
+  // Iterate over our content model children looking for the body.
+  nsCOMPtr<nsIContent> content = FindBodyElement(frame->GetContent());
+  if (!content)
+    return nullptr;
+
+  frame = content->GetPrimaryFrame();
+  if (!frame)
+     return nullptr;
+
+  // Make sure that the treebodyframe has a pointer to |this|.
+  nsTreeBodyFrame *treeBody = do_QueryFrame(frame);
+  NS_ENSURE_TRUE(treeBody && treeBody->GetTreeBoxObject() == this, nullptr);
+
+  mTreeBody = treeBody;
+  return mTreeBody;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::GetView(nsITreeView * *aView)
+{
+  if (!mTreeBody) {
+    if (!GetTreeBodyFrame()) {
+      // Don't return an uninitialised view
+      *aView = nullptr;
+      return NS_OK;
+    }
+
+    if (mView)
+      // Our new frame needs to initialise itself
+      return mTreeBody->GetView(aView);
+  }
+  if (!mView) {
+    nsCOMPtr<nsIDOMXULElement> xulele = do_QueryInterface(mContent);
+    if (xulele) {
+      // See if there is a XUL tree builder associated with the element
+      nsCOMPtr<nsIXULTemplateBuilder> builder;
+      xulele->GetBuilder(getter_AddRefs(builder));
+      mView = do_QueryInterface(builder);
+
+      if (!mView) {
+        // No tree builder, create a tree content view.
+        nsresult rv = NS_NewTreeContentView(getter_AddRefs(mView));
+        NS_ENSURE_SUCCESS(rv, rv);
+      }
+
+      // Initialise the frame and view
+      mTreeBody->SetView(mView);
+    }
+  }
+  NS_IF_ADDREF(*aView = mView);
+  return NS_OK;
+}
+
+already_AddRefed<nsITreeView>
+TreeBoxObject::GetView() {
+  nsCOMPtr<nsITreeView> view;
+  GetView(getter_AddRefs(view));
+  return view.forget();
+}
+
+static bool
+CanTrustView(nsISupports* aValue)
+{
+  // Untrusted content is only allowed to specify known-good views
+  if (nsContentUtils::IsCallerChrome())
+    return true;
+  nsCOMPtr<nsINativeTreeView> nativeTreeView = do_QueryInterface(aValue);
+  if (!nativeTreeView || NS_FAILED(nativeTreeView->EnsureNative())) {
+    // XXX ERRMSG need a good error here for developers
+    return false;
+  }
+  return true;
+}
+
+NS_IMETHODIMP TreeBoxObject::SetView(nsITreeView * aView)
+{
+  if (!CanTrustView(aView))
+    return NS_ERROR_DOM_SECURITY_ERR;
+
+  mView = aView;
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    body->SetView(aView);
+
+  return NS_OK;
+}
+
+void TreeBoxObject::SetView(nsITreeView* aView, ErrorResult& aRv)
+{
+  aRv = SetView(aView);
+}
+
+bool TreeBoxObject::Focused()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->GetFocused();
+  return false;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetFocused(bool* aFocused)
+{
+  *aFocused = Focused();
+  return NS_OK;
+}
+
+NS_IMETHODIMP TreeBoxObject::SetFocused(bool aFocused)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->SetFocused(aFocused);
+  return NS_OK;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetTreeBody(nsIDOMElement** aElement)
+{
+  *aElement = nullptr;
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->GetTreeBody(aElement);
+  return NS_OK;
+}
+
+already_AddRefed<Element>
+TreeBoxObject::GetTreeBody()
+{
+  nsCOMPtr<nsIDOMElement> el;
+  GetTreeBody(getter_AddRefs(el));
+  nsCOMPtr<Element> ret(do_QueryInterface(el));
+  return ret.forget();
+}
+
+already_AddRefed<nsTreeColumns>
+TreeBoxObject::GetColumns()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->Columns();
+  return nullptr;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetColumns(nsITreeColumns** aColumns)
+{
+  *aColumns = GetColumns().take();
+  return NS_OK;
+}
+
+int32_t TreeBoxObject::RowHeight()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->RowHeight();
+  return 0;
+}
+
+int32_t TreeBoxObject::RowWidth()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->RowWidth();
+  return 0;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetRowHeight(int32_t* aRowHeight)
+{
+  *aRowHeight = RowHeight();
+  return NS_OK;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetRowWidth(int32_t *aRowWidth)
+{
+  *aRowWidth = RowWidth();
+  return NS_OK;
+}
+
+int32_t TreeBoxObject::GetFirstVisibleRow()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->FirstVisibleRow();
+  return 0;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetFirstVisibleRow(int32_t *aFirstVisibleRow)
+{
+  *aFirstVisibleRow = GetFirstVisibleRow();
+  return NS_OK;
+}
+
+int32_t TreeBoxObject::GetLastVisibleRow()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->LastVisibleRow();
+  return 0;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetLastVisibleRow(int32_t *aLastVisibleRow)
+{
+  *aLastVisibleRow = GetLastVisibleRow();
+  return NS_OK;
+}
+
+int32_t TreeBoxObject::HorizontalPosition()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->GetHorizontalPosition();
+  return 0;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetHorizontalPosition(int32_t *aHorizontalPosition)
+{
+  *aHorizontalPosition = HorizontalPosition();
+  return NS_OK;
+}
+
+int32_t TreeBoxObject::GetPageLength()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->PageLength();
+  return 0;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetPageLength(int32_t *aPageLength)
+{
+  *aPageLength = GetPageLength();
+  return NS_OK;
+}
+
+NS_IMETHODIMP TreeBoxObject::GetSelectionRegion(nsIScriptableRegion **aRegion)
+{
+  *aRegion = nullptr;
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->GetSelectionRegion(aRegion);
+  return NS_OK;
+}
+
+already_AddRefed<nsIScriptableRegion>
+TreeBoxObject::SelectionRegion()
+{
+  nsCOMPtr<nsIScriptableRegion> region;
+  GetSelectionRegion(getter_AddRefs(region));
+  return region.forget();
+}
+
+NS_IMETHODIMP
+TreeBoxObject::EnsureRowIsVisible(int32_t aRow)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->EnsureRowIsVisible(aRow);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::EnsureCellIsVisible(int32_t aRow, nsITreeColumn* aCol)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->EnsureCellIsVisible(aRow, aCol);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::ScrollToRow(int32_t aRow)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame(true);
+  if (body)
+    return body->ScrollToRow(aRow);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::ScrollByLines(int32_t aNumLines)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->ScrollByLines(aNumLines);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::ScrollByPages(int32_t aNumPages)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->ScrollByPages(aNumPages);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::ScrollToCell(int32_t aRow, nsITreeColumn* aCol)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->ScrollToCell(aRow, aCol);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::ScrollToColumn(nsITreeColumn* aCol)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->ScrollToColumn(aCol);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::ScrollToHorizontalPosition(int32_t aHorizontalPosition)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->ScrollToHorizontalPosition(aHorizontalPosition);
+  return NS_OK;
+}
+
+NS_IMETHODIMP TreeBoxObject::Invalidate()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->Invalidate();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::InvalidateColumn(nsITreeColumn* aCol)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->InvalidateColumn(aCol);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::InvalidateRow(int32_t aIndex)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->InvalidateRow(aIndex);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::InvalidateCell(int32_t aRow, nsITreeColumn* aCol)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->InvalidateCell(aRow, aCol);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::InvalidateRange(int32_t aStart, int32_t aEnd)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->InvalidateRange(aStart, aEnd);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::InvalidateColumnRange(int32_t aStart, int32_t aEnd, nsITreeColumn* aCol)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->InvalidateColumnRange(aStart, aEnd, aCol);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::GetRowAt(int32_t x, int32_t y, int32_t *aRow)
+{
+  *aRow = 0;
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->GetRowAt(x, y, aRow);
+  return NS_OK;
+}
+
+int32_t
+TreeBoxObject::GetRowAt(int32_t x, int32_t y)
+{
+  int32_t row;
+  GetRowAt(x, y, &row);
+  return row;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::GetCellAt(int32_t aX, int32_t aY, int32_t *aRow,
+                         nsITreeColumn** aCol, nsAString& aChildElt)
+{
+  *aRow = 0;
+  *aCol = nullptr;
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body) {
+    nsAutoCString element;
+    nsresult retval = body->GetCellAt(aX, aY, aRow, aCol, element);
+    CopyUTF8toUTF16(element, aChildElt);
+    return retval;
+  }
+  return NS_OK;
+}
+
+void
+TreeBoxObject::GetCellAt(int32_t x, int32_t y, TreeCellInfo& aRetVal, ErrorResult& aRv)
+{
+  nsCOMPtr<nsITreeColumn> col;
+  GetCellAt(x, y, &aRetVal.mRow, getter_AddRefs(col), aRetVal.mChildElt);
+  aRetVal.mCol = col.forget().downcast<nsTreeColumn>();
+}
+
+void
+TreeBoxObject::GetCellAt(JSContext* cx,
+                         int32_t x, int32_t y,
+                         JS::Handle<JSObject*> rowOut,
+                         JS::Handle<JSObject*> colOut,
+                         JS::Handle<JSObject*> childEltOut,
+                         ErrorResult& aRv)
+{
+  int32_t row;
+  nsITreeColumn* col;
+  nsAutoString childElt;
+  GetCellAt(x, y, &row, &col, childElt);
+
+  JS::Rooted<JS::Value> v(cx);
+
+  if (!ToJSValue(cx, row, &v) ||
+      !JS_SetProperty(cx, rowOut, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+  if (!dom::WrapObject(cx, col, &v) ||
+      !JS_SetProperty(cx, colOut, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+  if (!ToJSValue(cx, childElt, &v) ||
+      !JS_SetProperty(cx, childEltOut, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+}
+
+NS_IMETHODIMP
+TreeBoxObject::GetCoordsForCellItem(int32_t aRow, nsITreeColumn* aCol, const nsAString& aElement,
+                                      int32_t *aX, int32_t *aY, int32_t *aWidth, int32_t *aHeight)
+{
+  *aX = *aY = *aWidth = *aHeight = 0;
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  NS_ConvertUTF16toUTF8 element(aElement);
+  if (body)
+    return body->GetCoordsForCellItem(aRow, aCol, element, aX, aY, aWidth, aHeight);
+  return NS_OK;
+}
+
+already_AddRefed<DOMRect>
+TreeBoxObject::GetCoordsForCellItem(int32_t row, nsTreeColumn& col, const nsAString& element, ErrorResult& aRv)
+{
+  int32_t x, y, w, h;
+  GetCoordsForCellItem(row, &col, element, &x, &y, &w, &h);
+  RefPtr<DOMRect> rect = new DOMRect(mContent, x, y, w, h);
+  return rect.forget();
+}
+
+void
+TreeBoxObject::GetCoordsForCellItem(JSContext* cx,
+                                    int32_t row,
+                                    nsTreeColumn& col,
+                                    const nsAString& element,
+                                    JS::Handle<JSObject*> xOut,
+                                    JS::Handle<JSObject*> yOut,
+                                    JS::Handle<JSObject*> widthOut,
+                                    JS::Handle<JSObject*> heightOut,
+                                    ErrorResult& aRv)
+{
+  int32_t x, y, w, h;
+  GetCoordsForCellItem(row, &col, element, &x, &y, &w, &h);
+  JS::Rooted<JS::Value> v(cx, JS::Int32Value(x));
+  if (!JS_SetProperty(cx, xOut, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+  v.setInt32(y);
+  if (!JS_SetProperty(cx, yOut, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+  v.setInt32(w);
+  if (!JS_SetProperty(cx, widthOut, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+  v.setInt32(h);
+  if (!JS_SetProperty(cx, heightOut, "value", v)) {
+    aRv.Throw(NS_ERROR_XPC_CANT_SET_OUT_VAL);
+    return;
+  }
+}
+
+NS_IMETHODIMP
+TreeBoxObject::IsCellCropped(int32_t aRow, nsITreeColumn* aCol, bool *aIsCropped)
+{
+  *aIsCropped = false;
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->IsCellCropped(aRow, aCol, aIsCropped);
+  return NS_OK;
+}
+
+bool
+TreeBoxObject::IsCellCropped(int32_t row, nsITreeColumn* col, ErrorResult& aRv)
+{
+  bool ret;
+  aRv = IsCellCropped(row, col, &ret);
+  return ret;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::RowCountChanged(int32_t aIndex, int32_t aDelta)
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->RowCountChanged(aIndex, aDelta);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::BeginUpdateBatch()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->BeginUpdateBatch();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::EndUpdateBatch()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->EndUpdateBatch();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+TreeBoxObject::ClearStyleAndImageCaches()
+{
+  nsTreeBodyFrame* body = GetTreeBodyFrame();
+  if (body)
+    return body->ClearStyleAndImageCaches();
+  return NS_OK;
+}
+
+void
+TreeBoxObject::ClearCachedValues()
+{
+  mTreeBody = nullptr;
+}
+
+JSObject*
+TreeBoxObject::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return TreeBoxObjectBinding::Wrap(aCx, this, aGivenProto);
+}
+
+} // namespace dom
+} // namespace mozilla
+
+// Creation Routine ///////////////////////////////////////////////////////////////////////
+
+using namespace mozilla::dom;
+
+nsresult
+NS_NewTreeBoxObject(nsIBoxObject** aResult)
+{
+  NS_ADDREF(*aResult = new TreeBoxObject());
+  return NS_OK;
+}
diff --git a/layout/xul/tree/TreeBoxObject.h b/layout/xul/tree/TreeBoxObject.h
new file mode 100644
index 0000000000..d997b5a63d
--- /dev/null
+++ b/layout/xul/tree/TreeBoxObject.h
@@ -0,0 +1,128 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TreeBoxObject_h
+#define mozilla_dom_TreeBoxObject_h
+
+#include "mozilla/dom/BoxObject.h"
+#include "nsITreeView.h"
+#include "nsITreeBoxObject.h"
+
+class nsTreeBodyFrame;
+class nsTreeColumn;
+class nsTreeColumns;
+
+namespace mozilla {
+namespace dom {
+
+struct TreeCellInfo;
+class DOMRect;
+
+class TreeBoxObject final : public BoxObject,
+                            public nsITreeBoxObject
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(TreeBoxObject, BoxObject)
+  NS_DECL_NSITREEBOXOBJECT
+
+  TreeBoxObject();
+
+  nsTreeBodyFrame* GetTreeBodyFrame(bool aFlushLayout = false);
+  nsTreeBodyFrame* GetCachedTreeBodyFrame() { return mTreeBody; }
+
+  //NS_PIBOXOBJECT interfaces
+  virtual void Clear() override;
+  virtual void ClearCachedValues() override;
+
+  // WebIDL
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+
+  already_AddRefed<nsTreeColumns> GetColumns();
+
+  already_AddRefed<nsITreeView> GetView();
+
+  void SetView(nsITreeView* arg, ErrorResult& aRv);
+
+  bool Focused();
+
+  already_AddRefed<Element> GetTreeBody();
+
+  int32_t RowHeight();
+
+  int32_t RowWidth();
+
+  int32_t HorizontalPosition();
+
+  already_AddRefed<nsIScriptableRegion> SelectionRegion();
+
+  int32_t GetFirstVisibleRow();
+
+  int32_t GetLastVisibleRow();
+
+  int32_t GetPageLength();
+
+  int32_t GetRowAt(int32_t x, int32_t y);
+
+  void GetCellAt(int32_t x, int32_t y, TreeCellInfo& aRetVal, ErrorResult& aRv);
+
+  already_AddRefed<DOMRect> GetCoordsForCellItem(int32_t row,
+                                                 nsTreeColumn& col,
+                                                 const nsAString& element,
+                                                 ErrorResult& aRv);
+
+  bool IsCellCropped(int32_t row, nsITreeColumn* col, ErrorResult& aRv);
+
+  // Deprecated APIs from old IDL
+  void GetCellAt(JSContext* cx,
+                 int32_t x, int32_t y,
+                 JS::Handle<JSObject*> rowOut,
+                 JS::Handle<JSObject*> colOut,
+                 JS::Handle<JSObject*> childEltOut,
+                 ErrorResult& aRv);
+
+  void GetCoordsForCellItem(JSContext* cx,
+                            int32_t row,
+                            nsTreeColumn& col,
+                            const nsAString& element,
+                            JS::Handle<JSObject*> xOut,
+                            JS::Handle<JSObject*> yOut,
+                            JS::Handle<JSObject*> widthOut,
+                            JS::Handle<JSObject*> heightOut,
+                            ErrorResult& aRv);
+
+  // Same signature (except for nsresult return type) as the XPIDL impls
+  // void Invalidate();
+  // void BeginUpdateBatch();
+  // void EndUpdateBatch();
+  // void ClearStyleAndImageCaches();
+  // void SetFocused(bool arg);
+  // void EnsureRowIsVisible(int32_t index);
+  // void EnsureCellIsVisible(int32_t row, nsITreeColumn* col);
+  // void ScrollToRow(int32_t index);
+  // void ScrollByLines(int32_t numLines);
+  // void ScrollByPages(int32_t numPages);
+  // void ScrollToCell(int32_t row, nsITreeColumn* col);
+  // void ScrollToColumn(nsITreeColumn* col);
+  // void ScrollToHorizontalPosition(int32_t horizontalPosition);
+  // void InvalidateColumn(nsITreeColumn* col);
+  // void InvalidateRow(int32_t index);
+  // void InvalidateCell(int32_t row, nsITreeColumn* col);
+  // void InvalidateRange(int32_t startIndex, int32_t endIndex);
+  // void InvalidateColumnRange(int32_t startIndex, int32_t endIndex, nsITreeColumn* col);
+  // void RowCountChanged(int32_t index, int32_t count);
+
+protected:
+  nsTreeBodyFrame* mTreeBody;
+  nsCOMPtr<nsITreeView> mView;
+
+private:
+  ~TreeBoxObject();
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif
diff --git a/layout/xul/tree/crashtests/307298-1.xul b/layout/xul/tree/crashtests/307298-1.xul
new file mode 100644
index 0000000000..57396755a4
--- /dev/null
+++ b/layout/xul/tree/crashtests/307298-1.xul
@@ -0,0 +1,21 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="var tree = document.getElementById('tree'), treeitem = document.getElementById('treeitem'); tree.parentNode.insertBefore(treeitem, tree);">
+
+<tree flex="1" id="tree">
+  <treecols>
+    <treecol id="name" label="Name" primary="true" flex="1"/>
+  </treecols>
+
+  <treechildren>
+    <treeitem id="treeitem">
+      <treerow>
+        <treecell label="Click the button below to crash"/>
+      </treerow>
+    </treeitem>
+  </treechildren>
+</tree>
+
+</window>
diff --git a/layout/xul/tree/crashtests/309732-1.xul b/layout/xul/tree/crashtests/309732-1.xul
new file mode 100644
index 0000000000..df955e14e5
--- /dev/null
+++ b/layout/xul/tree/crashtests/309732-1.xul
@@ -0,0 +1,30 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" class="reftest-wait" onload="setTimeout(boom, 30)">
+
+
+  <script>
+  function boom()
+  {
+    document.documentElement.appendChild(document.getElementById("TC")); 
+    document.documentElement.appendChild(document.getElementById("TI"));
+
+    document.documentElement.removeAttribute("class");
+  }
+  </script>
+
+<tree flex="1">
+    <treecols>
+      <treecol label="Name"/>
+    </treecols>
+    <treechildren id="TC">
+      <treeitem id="TI">
+        <treerow>
+          <treecell label="First treecell"/>
+        </treerow>
+      </treeitem>
+    </treechildren>
+  </tree>
+</window>
diff --git a/layout/xul/tree/crashtests/309732-2.xul b/layout/xul/tree/crashtests/309732-2.xul
new file mode 100644
index 0000000000..9c65e73799
--- /dev/null
+++ b/layout/xul/tree/crashtests/309732-2.xul
@@ -0,0 +1,31 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" class="reftest-wait" onload="setTimeout(boom, 30)">
+
+  <script>
+  function boom()
+  {
+    document.documentElement.appendChild(document.getElementById('TC'));   
+    document.getElementById('TI').hidden = false;
+    
+    document.documentElement.removeAttribute("class");
+  }
+  </script>
+
+
+  <tree flex="1">
+    <treecols>
+      <treecol label="Name" flex="1"/>
+    </treecols>
+    <treechildren id="TC">
+      <treeitem>
+        <treerow>
+          <treecell label="First treecell"/>
+        </treerow>
+      </treeitem>
+    </treechildren>
+  </tree>
+  <treeitem id="TI" hidden="true"/>
+</window>
diff --git a/layout/xul/tree/crashtests/366583-1.xul b/layout/xul/tree/crashtests/366583-1.xul
new file mode 100644
index 0000000000..db37b444e8
--- /dev/null
+++ b/layout/xul/tree/crashtests/366583-1.xul
@@ -0,0 +1,43 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="boom1();"
+        class="reftest-wait">
+
+<script>
+        
+var tree;
+
+function boom1()
+{
+  tree = document.getElementById("tree");
+  tree.style.position = "fixed";
+  setTimeout(boom2, 30);
+}
+
+function boom2()
+{
+  tree.style.overflow = "visible";
+  document.documentElement.removeAttribute("class");
+}
+</script>
+
+<tree rows="6" id="tree" style="display: list-item; overflow: auto; visibility: collapse;">
+  <treecols>
+      <treecol id="firstname" label="First Name" primary="true" flex="3"/>
+      <treecol id="lastname" label="Last Name" flex="7"/>
+  </treecols>
+
+  <treechildren>
+    <treeitem container="true" open="true">
+      <treerow>
+        <treecell label="Foo"/>
+      </treerow>
+    </treeitem>
+  </treechildren>
+</tree>
+
+
+</window>
diff --git a/layout/xul/tree/crashtests/380217-1.xul b/layout/xul/tree/crashtests/380217-1.xul
new file mode 100644
index 0000000000..b834f7e1fc
--- /dev/null
+++ b/layout/xul/tree/crashtests/380217-1.xul
@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns:html="http://www.w3.org/1999/xhtml"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="document.documentElement.style.content = '\'a\'';">
+        
+<html:style>
+* { position: fixed; }
+</html:style>
+
+<tree rows="6">
+  <treecols>
+      <treecol id="firstname" label="First Name" primary="true"/>
+  </treecols>
+  <treechildren>
+    <treeitem>
+      <treerow>
+        <treecell/>
+      </treerow>
+    </treeitem>
+  </treechildren>
+</tree>
+
+</window>
diff --git a/layout/xul/tree/crashtests/382444-1-inner.html b/layout/xul/tree/crashtests/382444-1-inner.html
new file mode 100644
index 0000000000..d59a2e787e
--- /dev/null
+++ b/layout/xul/tree/crashtests/382444-1-inner.html
@@ -0,0 +1,15 @@
+<html>

+<head>

+<title>Testcase bug - Crash [@ nsINodeInfo::Equals] with underflow event, tree stuff and removing window</title>

+</head>

+<body>

+<iframe src="data:application/vnd.mozilla.xul+xml;charset=utf-8,%3Cwindow%20xmlns%3D%22http%3A//www.mozilla.org/keymaster/gatekeeper/there.is.only.xul%22%3E%0A%3Ctree%20style%3D%22overflow%3A%20auto%3B%20display%3A%20-moz-inline-box%3B%22%3E%0A%3Ctreeitem%20style%3D%22overflow%3A%20scroll%3B%20display%3A%20table-cell%3B%22%3E%0A%3Ctreechildren%20style%3D%22%20display%3A%20table-row%3B%22%3E%0A%3Ctreeitem%20id%3D%22a%22%20style%3D%22display%3A%20table-cell%3B%22%3E%0A%3C/treeitem%3E%0A%3C/treechildren%3E%0A%3C/treeitem%3E%0A%0A%3C/tree%3E%0A%0A%3Cscript%20xmlns%3D%22http%3A//www.w3.org/1999/xhtml%22%3E%0Afunction%20doe%28%29%20%7B%0Adocument.getElementById%28%27a%27%29.parentNode.removeChild%28document.getElementById%28%27a%27%29%29%3B%0A%7D%0AsetTimeout%28doe%2C%20100%29%3B%0Adocument.addEventListener%28%27underflow%27%2C%20function%28e%29%20%7Bwindow.frameElement.parentNode.removeChild%28window.frameElement%29%20%7D%2C%20true%29%3B%0Awindow.addEventListener%28%27underflow%27%2C%20function%28e%29%20%7Bwindow.frameElement.parentNode.removeChild%28window.frameElement%29%20%7D%2C%20true%29%3B%0A%3C/script%3E%0A%3C/window%3E" id="content"></iframe>

+

+<script>

+function doe() {

+window.location.reload();

+}

+setTimeout(doe, 500);

+</script>

+</body>

+</html>

diff --git a/layout/xul/tree/crashtests/382444-1.html b/layout/xul/tree/crashtests/382444-1.html
new file mode 100644
index 0000000000..8926cf16d7
--- /dev/null
+++ b/layout/xul/tree/crashtests/382444-1.html
@@ -0,0 +1,9 @@
+<html class="reftest-wait">
+<head>
+<script>
+setTimeout('document.documentElement.className = ""', 500);
+</script>
+<body>
+<iframe src="382444-1-inner.html"></iframe>
+</body>
+</html>
diff --git a/layout/xul/tree/crashtests/391178-1.xhtml b/layout/xul/tree/crashtests/391178-1.xhtml
new file mode 100644
index 0000000000..0f4b16cd99
--- /dev/null
+++ b/layout/xul/tree/crashtests/391178-1.xhtml
@@ -0,0 +1,41 @@
+<html xmlns="http://www.w3.org/1999/xhtml" class="reftest-wait">
+<head>
+<script>
+
+var ccc;
+
+function boom()
+{
+  var XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+
+  var hbox = document.createElementNS(XUL_NS, 'hbox');
+  var tree = document.createElementNS(XUL_NS, 'tree');
+  var treecol = document.createElementNS(XUL_NS, 'treecol');
+
+  ccc = document.getElementById("ccc");
+
+  ccc.style.position = "fixed";
+
+  hbox.appendChild(treecol);
+  tree.appendChild(hbox);
+  ccc.appendChild(tree);
+  
+  setTimeout(boom2, 200);
+}
+
+function boom2()
+{
+  ccc.style.position = "";
+  document.documentElement.removeAttribute("class");
+}
+
+</script>
+</head>
+
+<body onload="boom();">
+
+<div id="ccc">
+</div>
+
+</body>
+</html>
diff --git a/layout/xul/tree/crashtests/391178-2.xul b/layout/xul/tree/crashtests/391178-2.xul
new file mode 100644
index 0000000000..491fbe77b5
--- /dev/null
+++ b/layout/xul/tree/crashtests/391178-2.xul
@@ -0,0 +1,20 @@
+<?xml-stylesheet href="chrome://browser/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" xmlns:html="http://www.w3.org/1999/xhtml" class="reftest-wait">
+
+<tree id="a" style="position: fixed;">
+  <box style=" display: -moz-box; position: fixed;">
+    <treecol style=" display: -moz-box;"/>
+  </box>
+  <box style="position: fixed;">
+    <treechildren style="display: -moz-box; position: absolute;"/>
+  </box>
+</tree>
+
+<script xmlns="http://www.w3.org/1999/xhtml">
+function removestyles(){
+  document.getElementById('a').removeAttribute('style');
+  document.documentElement.removeAttribute("class");
+}
+setTimeout(removestyles, 100);
+</script>
+</window>
diff --git a/layout/xul/tree/crashtests/393665-1.xul b/layout/xul/tree/crashtests/393665-1.xul
new file mode 100644
index 0000000000..6fb5ec0c9e
--- /dev/null
+++ b/layout/xul/tree/crashtests/393665-1.xul
@@ -0,0 +1,3 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <treechildren style="display: block" />
+</window>
diff --git a/layout/xul/tree/crashtests/399227-1.xul b/layout/xul/tree/crashtests/399227-1.xul
new file mode 100644
index 0000000000..bfc381892a
--- /dev/null
+++ b/layout/xul/tree/crashtests/399227-1.xul
@@ -0,0 +1,44 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" class="reftest-wait" onload="setTimeout(boom, 30)">
+
+
+  <script>
+  function boom()
+  {
+    var tree = document.getElementById("thetree");
+    var selection = tree.view.selection;
+
+    selection.select(0);
+    tree.parentNode.removeChild(tree);
+
+    // This is expected to throw an error (it used to crash).
+    try {
+      selection.rangedSelect(1, 1, false);
+    }
+    catch (ex) {}
+
+    document.documentElement.removeAttribute("class");
+  }
+  </script>
+
+<tree flex="1" id="thetree">
+    <treecols>
+      <treecol label="Name"/>
+    </treecols>
+    <treechildren id="TC">
+      <treeitem id="TI1">
+        <treerow>
+          <treecell label="First treecell"/>
+        </treerow>
+      </treeitem>
+      <treeitem id="TI2">
+        <treerow>
+          <treecell label="Second treecell"/>
+        </treerow>
+      </treeitem>
+    </treechildren>
+  </tree>
+</window>
diff --git a/layout/xul/tree/crashtests/399227-2.xul b/layout/xul/tree/crashtests/399227-2.xul
new file mode 100644
index 0000000000..55665ec475
--- /dev/null
+++ b/layout/xul/tree/crashtests/399227-2.xul
@@ -0,0 +1,50 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" class="reftest-wait" onload="setTimeout(boom, 30);">
+
+
+  <script>
+  function boom()
+  {
+    var tree = document.getElementById("thetree");
+    var selection = tree.view.selection;
+    var treecolumn0 = tree.columns[0];
+    var treecolumn1 = tree.columns[1];
+
+    selection.select(0);
+    selection.currentColumn = treecolumn0;
+    tree.parentNode.removeChild(tree);
+
+    // This is expected to throw an error (it used to crash).
+    try {
+      selection.currentColumn = treecolumn1;
+    }
+    catch (ex) {}
+
+    document.documentElement.removeAttribute("class");
+  }
+  </script>
+
+<tree flex="1" id="thetree" seltype="cell">
+    <treecols>
+      <treecol label="Name"/>
+      <treecol label="Test"/>
+    </treecols>
+    <treechildren id="TC">
+      <treeitem id="TI1">
+        <treerow>
+          <treecell label="First treecell"/>
+          <treecell label="Second treecell"/>
+        </treerow>
+      </treeitem>
+      <treeitem id="TI2">
+        <treerow>
+          <treecell label="Third treecell"/>
+          <treecell label="Fourth treecell"/>
+        </treerow>
+      </treeitem>
+    </treechildren>
+  </tree>
+</window>
diff --git a/layout/xul/tree/crashtests/399692-1.xhtml b/layout/xul/tree/crashtests/399692-1.xhtml
new file mode 100644
index 0000000000..97eec26742
--- /dev/null
+++ b/layout/xul/tree/crashtests/399692-1.xhtml
@@ -0,0 +1,10 @@
+<html xmlns="http://www.w3.org/1999/xhtml"
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<head>
+</head>
+<body>
+
+<xul:treechildren style="display: inline;" />
+
+</body>
+</html>
diff --git a/layout/xul/tree/crashtests/399715-1.xhtml b/layout/xul/tree/crashtests/399715-1.xhtml
new file mode 100644
index 0000000000..ea0a20cfa2
--- /dev/null
+++ b/layout/xul/tree/crashtests/399715-1.xhtml
@@ -0,0 +1,9 @@
+<html xmlns="http://www.w3.org/1999/xhtml"
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+      
+<body style="float: right;" onload="document.body.style.cssFloat = '';">
+
+<xul:tree><xul:hbox><xul:treecol /></xul:hbox></xul:tree>
+
+</body>
+</html>
diff --git a/layout/xul/tree/crashtests/409807-1.xul b/layout/xul/tree/crashtests/409807-1.xul
new file mode 100644
index 0000000000..a3af3da41b
--- /dev/null
+++ b/layout/xul/tree/crashtests/409807-1.xul
@@ -0,0 +1,25 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="boom();">
+
+<script type="text/javascript">
+
+function boom()
+{
+  var tree = document.getElementById("tree");
+  var tc = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "treechildren");
+  
+  document.addEventListener("DOMAttrModified", m, false);
+  
+  tree.appendChild(tc);
+  
+  function m()
+  {
+    document.removeEventListener("DOMAttrModified", m, false);
+    tree.removeChild(tc);
+  }
+}
+
+</script>
+
+<tree id="tree" />
+
+</window>
diff --git a/layout/xul/tree/crashtests/414170-1.xul b/layout/xul/tree/crashtests/414170-1.xul
new file mode 100644
index 0000000000..f3bc1d1343
--- /dev/null
+++ b/layout/xul/tree/crashtests/414170-1.xul
@@ -0,0 +1,20 @@
+<?xml version="1.0"?>
+
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="boom();">
+        
+<script type="text/javascript">
+
+function boom()
+{
+  var option = document.createElementNS("http://www.w3.org/1999/xhtml", "option");
+  document.getElementById("tc").appendChild(option);
+}
+
+</script>
+
+<tree><treechildren id="tc"><hbox/></treechildren></tree>
+
+</window>
diff --git a/layout/xul/tree/crashtests/430394-1.xul b/layout/xul/tree/crashtests/430394-1.xul
new file mode 100644
index 0000000000..63f4c37804
--- /dev/null
+++ b/layout/xul/tree/crashtests/430394-1.xul
@@ -0,0 +1,8 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<tree id="a" style="content: 't';" rows="-2">
+  <menuitem id="b" onoverflow="event.currentTarget.parentNode.removeAttribute('style')">
+    <treechildren style="display: block;" onoverflow="event.target.parentNode.removeChild(event.target)" />
+    <treechildren style="display: block;" ordinal="0.5"/>
+  </menuitem>
+</tree>
+</window>
\ No newline at end of file
diff --git a/layout/xul/tree/crashtests/454186-1.xul b/layout/xul/tree/crashtests/454186-1.xul
new file mode 100644
index 0000000000..edf266e43b
--- /dev/null
+++ b/layout/xul/tree/crashtests/454186-1.xul
@@ -0,0 +1,23 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+<tree flex="1">
+  <treecols>
+    <treecol label="test" flex="1" type="progressmeter" />
+  </treecols>
+  <treechildren>
+    <treeitem>
+      <treerow>
+        <treecell value="50" mode="normal" />
+      </treerow>
+    </treeitem>
+    <treeitem>
+      <treerow>
+        <treecell mode="undetermined" />
+      </treerow>
+    </treeitem>
+  </treechildren>
+</tree>
+
+</window>
diff --git a/layout/xul/tree/crashtests/479931-1.xhtml b/layout/xul/tree/crashtests/479931-1.xhtml
new file mode 100644
index 0000000000..458a192501
--- /dev/null
+++ b/layout/xul/tree/crashtests/479931-1.xhtml
@@ -0,0 +1,19 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+<head>
+<script type="text/javascript">
+
+function boom()
+{
+  var o = document.createElementNS("http://www.w3.org/1999/xhtml", "option");
+  var q = document.getElementById("q");
+  q.appendChild(o);
+}
+
+</script>
+</head>
+<body onload="boom();">
+
+<xul:tree><xul:treechildren id="q"><div/></xul:treechildren></xul:tree>
+
+</body>
+</html>
diff --git a/layout/xul/tree/crashtests/509602-1-overlay.xul b/layout/xul/tree/crashtests/509602-1-overlay.xul
new file mode 100644
index 0000000000..f5cecd40ed
--- /dev/null
+++ b/layout/xul/tree/crashtests/509602-1-overlay.xul
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>

+<overlay xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

+<box id="b">
+<box onDOMAttrModified="event.target.parentNode.removeChild(event.target)" id="d"/>
+<tree/>
+</box>
+
+<tree>
+<box  id="b" observes="d"/>
+<treechildren observes="b"/>
+</tree>
+</overlay>
\ No newline at end of file
diff --git a/layout/xul/tree/crashtests/509602-1.xul b/layout/xul/tree/crashtests/509602-1.xul
new file mode 100644
index 0000000000..a1cdcf1ccc
--- /dev/null
+++ b/layout/xul/tree/crashtests/509602-1.xul
@@ -0,0 +1,3 @@
+<?xul-overlay href="509602-1-overlay.xul"?>

+<?xml-stylesheet href="chrome://browser/skin/" type="text/css"?>

+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"/>
\ No newline at end of file
diff --git a/layout/xul/tree/crashtests/585815-iframe.xul b/layout/xul/tree/crashtests/585815-iframe.xul
new file mode 100644
index 0000000000..ce9d294485
--- /dev/null
+++ b/layout/xul/tree/crashtests/585815-iframe.xul
@@ -0,0 +1,72 @@
+<?xml version="1.0"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="setInterval(run, 25)">
+
+<tree flex="1" rows="2">
+ <treecols>  
+    <treecol id="sender" label="Sender" flex="1"/>  
+    <treecol id="subject" label="Subject" flex="2"/>  
+  </treecols>  
+  <treechildren>
+    <treeitem>
+      <treerow>
+        <treecell label="joe@somewhere.com"/>  
+        <treecell label="Top secret plans"/>  
+      </treerow>
+    </treeitem>  
+    <treeitem>  
+      <treerow>  
+        <treecell label="mel@whereever.com"/>  
+        <treecell label="Let's do lunch"/>  
+      </treerow>  
+    </treeitem> 
+    <treeitem>  
+      <treerow>  
+        <treecell label="mel@whereever.com"/>  
+        <treecell label="Let's do lunch"/>  
+      </treerow>  
+    </treeitem> 
+    <treeitem>  
+      <treerow>  
+        <treecell label="mel@whereever.com"/>  
+        <treecell label="Let's do lunch"/>  
+      </treerow>  
+    </treeitem> 
+    <treeitem>  
+      <treerow>  
+        <treecell label="mel@whereever.com"/>  
+        <treecell label="Let's do lunch"/>  
+      </treerow>  
+    </treeitem> 
+    <treeitem>  
+      <treerow>  
+        <treecell label="mel@whereever.com"/>  
+        <treecell label="Let's do lunch"/>  
+      </treerow>  
+    </treeitem> 
+    <treeitem>  
+      <treerow>  
+        <treecell label="mel@whereever.com"/>  
+        <treecell label="Let's do lunch"/>  
+      </treerow>  
+    </treeitem> 
+    <treeitem>  
+      <treerow>  
+        <treecell label="mel@whereever.com"/>  
+        <treecell label="Let's do lunch"/>  
+      </treerow>  
+    </treeitem> 
+  </treechildren>
+</tree>
+
+<script type="text/javascript"><![CDATA[
+function run() {
+  var tree = document.getElementsByTagName("tree")[0];
+  var sel = tree.view.selection;
+  sel.rangedSelect(0, 0, true);
+  sel.rangedSelect(1000, 1001, true);
+  sel.adjustSelection(1, 0x7fffffff);
+}
+]]></script>
+
+</window>
diff --git a/layout/xul/tree/crashtests/585815.html b/layout/xul/tree/crashtests/585815.html
new file mode 100644
index 0000000000..0b8b018274
--- /dev/null
+++ b/layout/xul/tree/crashtests/585815.html
@@ -0,0 +1,18 @@
+<!DOCTYPE HTML>
+<html class="reftest-wait"><head>
+    <meta charset="utf-8">
+    <title>Testcase for bug 585815</title>
+<script>
+function done()
+{
+  document.documentElement.removeAttribute("class");
+}
+</script>
+</head>
+<body onload="setTimeout(done,1000)">
+
+<iframe src="585815-iframe.xul"></iframe>
+
+
+</body>
+</html>
diff --git a/layout/xul/tree/crashtests/601427.html b/layout/xul/tree/crashtests/601427.html
new file mode 100644
index 0000000000..cd9574eef6
--- /dev/null
+++ b/layout/xul/tree/crashtests/601427.html
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<html class="reftest-wait">
+<script>
+
+var onPaintFunctions =
+[
+  function() { document.documentElement.style.MozAppearance = "treeheadersortarrow"; },
+  function() { document.documentElement.style.position = "fixed"; },
+  function() { document.documentElement.removeAttribute("class"); }
+];
+
+var i = 0;
+
+function advance()
+{
+  var f = onPaintFunctions[i++];
+  if (f)
+    f();
+}
+
+function start()
+{
+  window.addEventListener("MozAfterPaint", advance, true);
+  advance();
+}
+
+window.addEventListener("load", start, false);
+
+</script>
+</html>
diff --git a/layout/xul/tree/crashtests/730441-1.xul b/layout/xul/tree/crashtests/730441-1.xul
new file mode 100644
index 0000000000..a31c3b63fc
--- /dev/null
+++ b/layout/xul/tree/crashtests/730441-1.xul
@@ -0,0 +1,54 @@
+<?xml version="1.0"?>
+<!--
+Program received signal SIGSEGV, Segmentation fault.
+0xb6457185 in nsIContent::SetAttr (this=0x0, aNameSpaceID=0, aName=0xb0cb064c, aValue=..., aNotify=1) at ../../dist/include/nsIContent.h:285
+285	    return SetAttr(aNameSpaceID, aName, nsnull, aValue, aNotify);
+(gdb) p this
+$6 = (nsIContent * const) 0x0
+(gdb) bt 3
+#0  0xb6457185 in nsIContent::SetAttr (this=0x0, aNameSpaceID=0, aName=0xb0cb064c, aValue=..., aNotify=1) at ../../dist/include/nsIContent.h:285
+#1  0xb6b72072 in nsTreeColumns::RestoreNaturalOrder (this=0xaaf83cc0) at layout/xul/base/src/tree/src/nsTreeColumns.cpp:605
+#2  0xb736c76f in NS_InvokeByIndex_P () at xpcom/reflect/xptcall/md/unix/xptcinvoke_gcc_x86_unix.cpp:69
+(More stack frames follow...)
+(gdb) frame 1
+#1  0xb6b72072 in nsTreeColumns::RestoreNaturalOrder (this=0xaaf83cc0) at layout/xul/base/src/tree/src/nsTreeColumns.cpp:605
+605	    child->SetAttr(kNameSpaceID_None, nsGkAtoms::ordinal, ordinal, PR_TRUE);
+(gdb) list
+600	  PRUint32 numChildren = colsContent->GetChildCount();
+601	  for (PRUint32 i = 0; i < numChildren; ++i) {
+602	    nsIContent *child = colsContent->GetChildAt(i);
+603	    nsAutoString ordinal;
+604	    ordinal.AppendInt(i);
+605	    child->SetAttr(kNameSpaceID_None, nsGkAtoms::ordinal, ordinal, PR_TRUE);
+606	  }
+(gdb) p child
+$7 = (nsIContent *) 0x0
+
+First loop iteration: |child->SetAttr()| dispatches "DOMAttrModified" event.
+Event listener removes next column. Second loop iteration: |colsContent->GetChildAt(i)|
+returns null. Then we have |null->SetAttr()|.
+-->
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="run();">
+<tree id="tree">
+  <treecols>
+    <treecol id="col1"/>
+    <treecol id="col2"/>
+  </treecols>
+  <treechildren/>
+</tree>
+<script type="text/javascript"><![CDATA[
+function listener() {
+  var col2 = document.getElementById("col2");
+  col2.parentNode.removeChild(col2);
+}
+
+function run() {
+  var col1 = document.getElementById("col1");
+  col1.addEventListener("DOMAttrModified", listener, true);
+  var tree = document.getElementById("tree");
+  tree.columns.restoreNaturalOrder();
+}
+]]></script>
+</window>
+
diff --git a/layout/xul/tree/crashtests/730441-2.xul b/layout/xul/tree/crashtests/730441-2.xul
new file mode 100644
index 0000000000..02b3a307e7
--- /dev/null
+++ b/layout/xul/tree/crashtests/730441-2.xul
@@ -0,0 +1,52 @@
+<?xml version="1.0"?>
+<!--
+Program received signal SIGSEGV, Segmentation fault.
+0xb6b720a6 in nsTreeColumns::RestoreNaturalOrder (this=0xa947a580) at layout/xul/base/src/tree/src/nsTreeColumns.cpp:610
+610	  mTree->Invalidate();
+(gdb) bt 3
+#0  0xb6b720a6 in nsTreeColumns::RestoreNaturalOrder (this=0xa947a580) at layout/xul/base/src/tree/src/nsTreeColumns.cpp:610
+#1  0xb736c76f in NS_InvokeByIndex_P () at xpcom/reflect/xptcall/md/unix/xptcinvoke_gcc_x86_unix.cpp:69
+#2  0xb6171901 in XPCWrappedNative::CallMethod (ccx=..., mode=XPCWrappedNative::CALL_METHOD)
+    at js/src/xpconnect/src/xpcwrappednative.cpp:2722
+(More stack frames follow...)
+(gdb) list
+605	    child->SetAttr(kNameSpaceID_None, nsGkAtoms::ordinal, ordinal, PR_TRUE);
+606	  }
+607	
+608	  nsTreeColumns::InvalidateColumns();
+609	
+610	  mTree->Invalidate();
+611	
+612	  return NS_OK;
+613	}
+614	
+(gdb) p mTree
+$9 = (nsITreeBoxObject *) 0x0
+
+|child->SetAttr()| dispatches "DOMAttrModified" event. Event listener removes
+whole tree, |mTree| is being set to null. Then we have |null->Invalidate()|.
+-->
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="run();">
+<tree id="tree">
+  <treecols>
+    <treecol id="col"/>
+  </treecols>
+  <treechildren/>
+</tree>
+<script type="text/javascript"><![CDATA[
+var tree = null;
+
+function listener() {
+  tree.parentNode.removeChild(tree);
+}
+
+function run() {
+  col = document.getElementById("col");
+  col.addEventListener("DOMAttrModified", listener, true);
+  tree = document.getElementById("tree");
+  tree.columns.restoreNaturalOrder();
+}
+]]></script>
+</window>
+
diff --git a/layout/xul/tree/crashtests/730441-3.xul b/layout/xul/tree/crashtests/730441-3.xul
new file mode 100644
index 0000000000..2cf74d1b9c
--- /dev/null
+++ b/layout/xul/tree/crashtests/730441-3.xul
@@ -0,0 +1,38 @@
+<?xml version="1.0"?>
+<!--
+###!!! ASSERTION: You can't dereference a NULL nsCOMPtr with operator->().: 'mRawPtr != 0', file ../../../../dist/include/nsCOMPtr.h, line 796
+
+Program received signal SIGSEGV, Segmentation fault.
+0xb6b7463a in nsTreeContentView::SetTree (this=0xb0ba2510, aTree=0xaaecece0) at layout/xul/base/src/tree/src/nsTreeContentView.cpp:571
+571        boxObject->GetElement(getter_AddRefs(element));
+(gdb) bt 3
+#0  0xb6b7463a in nsTreeContentView::SetTree (this=0xb0ba2510, aTree=0xaaecece0) at layout/xul/base/src/tree/src/nsTreeContentView.cpp:571
+#1  0xb736c76f in NS_InvokeByIndex_P () at xpcom/reflect/xptcall/md/unix/xptcinvoke_gcc_x86_unix.cpp:69
+#2  0xb6171901 in XPCWrappedNative::CallMethod (ccx=..., mode=XPCWrappedNative::CALL_METHOD)
+    at js/src/xpconnect/src/xpcwrappednative.cpp:2722
+(More stack frames follow...)
+(gdb) list 566
+561    nsTreeContentView::SetTree(nsITreeBoxObject* aTree)
+562    {
+563      ClearRows();
+564
+565      mBoxObject = aTree;
+566
+567      if (aTree && !mRoot) {
+568        // Get our root element
+569        nsCOMPtr<nsIBoxObject> boxObject = do_QueryInterface(mBoxObject);
+570        nsCOMPtr<nsIDOMElement> element;
+571        boxObject->GetElement(getter_AddRefs(element));
+(gdb) p boxObject
+$16 = {mRawPtr = 0x0}
+
+|aTree| does not implement |nsIBoxObject|, so |do_QueryInterface(mBoxObject)|
+returns null. Then we have |null->GetElement()|.
+-->
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="document.getElementById('tree').view.setTree({});">
+<tree id="tree">
+  <treechildren/>
+</tree>
+</window>
+
diff --git a/layout/xul/tree/crashtests/crashtests.list b/layout/xul/tree/crashtests/crashtests.list
new file mode 100644
index 0000000000..d462e95505
--- /dev/null
+++ b/layout/xul/tree/crashtests/crashtests.list
@@ -0,0 +1,24 @@
+load 307298-1.xul
+load 309732-1.xul
+load 309732-2.xul
+load 366583-1.xul
+load 380217-1.xul
+load 382444-1.html
+load 391178-1.xhtml
+load 391178-2.xul
+load 393665-1.xul
+load 399227-1.xul
+load 399227-2.xul
+load 399692-1.xhtml
+load 399715-1.xhtml
+load 409807-1.xul
+load 414170-1.xul
+load 430394-1.xul
+load 454186-1.xul
+load 479931-1.xhtml
+load 509602-1.xul
+load 585815.html
+load 601427.html
+load 730441-1.xul
+load 730441-2.xul
+load 730441-3.xul
diff --git a/layout/xul/tree/moz.build b/layout/xul/tree/moz.build
new file mode 100644
index 0000000000..ccac5bde97
--- /dev/null
+++ b/layout/xul/tree/moz.build
@@ -0,0 +1,53 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+with Files('**'):
+    BUG_COMPONENT = ('Core', 'XP Toolkit/Widgets: XUL')
+
+XPIDL_SOURCES += [
+    'nsITreeBoxObject.idl',
+    'nsITreeColumns.idl',
+    'nsITreeContentView.idl',
+    'nsITreeSelection.idl',
+    'nsITreeView.idl',
+]
+
+XPIDL_MODULE = 'layout_xul_tree'
+
+EXPORTS += [
+    'nsTreeColFrame.h',
+    'nsTreeColumns.h',
+    'nsTreeUtils.h',
+]
+
+EXPORTS.mozilla.dom += [
+    'TreeBoxObject.h'
+]
+
+UNIFIED_SOURCES += [
+    'nsTreeBodyFrame.cpp',
+    'nsTreeColFrame.cpp',
+    'nsTreeColumns.cpp',
+    'nsTreeContentView.cpp',
+    'nsTreeImageListener.cpp',
+    'nsTreeSelection.cpp',
+    'nsTreeStyleCache.cpp',
+    'nsTreeUtils.cpp',
+    'TreeBoxObject.cpp',
+]
+
+FINAL_LIBRARY = 'xul'
+LOCAL_INCLUDES += [
+    '..',
+    '../../base',
+    '../../forms',
+    '../../generic',
+    '../../style',
+    '/dom/base',
+]
+
+if CONFIG['GNU_CXX']:
+    CXXFLAGS += ['-Wno-error=shadow']
diff --git a/layout/xul/tree/nsITreeBoxObject.idl b/layout/xul/tree/nsITreeBoxObject.idl
new file mode 100644
index 0000000000..638c8a41ca
--- /dev/null
+++ b/layout/xul/tree/nsITreeBoxObject.idl
@@ -0,0 +1,189 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIDOMElement;
+interface nsITreeView;
+interface nsITreeSelection;
+interface nsITreeColumn;
+interface nsITreeColumns;
+interface nsIScriptableRegion;
+
+[scriptable, uuid(f3da0c5e-51f5-45f0-b2cd-6be3ab6847ae)]
+interface nsITreeBoxObject : nsISupports
+{
+  /**
+   * Obtain the columns.
+   */
+  readonly attribute nsITreeColumns columns;
+
+  /**
+   * The view that backs the tree and that supplies it with its data.
+   * It is dynamically settable, either using a view attribute on the
+   * tree tag or by setting this attribute to a new value.
+   */
+  attribute nsITreeView view;
+
+  /**
+   * Whether or not we are currently focused.
+   */
+  attribute boolean focused;
+
+  /**
+   * Obtain the treebody content node
+   */
+  readonly attribute nsIDOMElement treeBody;
+
+  /**
+   * Obtain the height of a row.
+   */
+  readonly attribute long rowHeight;
+
+  /**
+   * Obtain the width of a row.
+   */
+  readonly attribute long rowWidth;
+
+  /**
+   * Get the pixel position of the horizontal scrollbar. 
+   */
+  readonly attribute long horizontalPosition;
+
+  /**
+   * Return the region for the visible parts of the selection, in device pixels.
+   */
+  readonly attribute nsIScriptableRegion selectionRegion;
+
+  /**
+   * Get the index of the first visible row.
+   */
+  long getFirstVisibleRow();
+
+  /**
+   * Get the index of the last visible row.
+   */
+  long getLastVisibleRow();
+
+  /**
+   * Gets the number of possible visible rows.
+   */
+  long getPageLength();
+
+  /**
+   * Ensures that a row at a given index is visible.
+   */
+  void ensureRowIsVisible(in long index);
+
+  /**
+   * Ensures that a given cell in the tree is visible.
+   */
+  void ensureCellIsVisible(in long row, in nsITreeColumn col);
+
+  /**
+   * Scrolls such that the row at index is at the top of the visible view.
+   */
+  void scrollToRow(in long index);
+
+  /**
+   * Scroll the tree up or down by numLines lines. Positive
+   * values move down in the tree. Prevents scrolling off the
+   * end of the tree. 
+   */
+  void scrollByLines(in long numLines);
+
+  /**
+   * Scroll the tree up or down by numPages pages. A page
+   * is considered to be the amount displayed by the tree.
+   * Positive values move down in the tree. Prevents scrolling
+   * off the end of the tree.
+   */
+  void scrollByPages(in long numPages);
+  
+  /**
+   * Scrolls such that a given cell is visible (if possible) 
+   * at the top left corner of the visible view. 
+   */
+  void scrollToCell(in long row, in nsITreeColumn col);
+
+  /**
+   * Scrolls horizontally so that the specified column is 
+   * at the left of the view (if possible).
+   */
+  void scrollToColumn(in nsITreeColumn col);
+
+  /**
+   * Scroll to a specific horizontal pixel position.
+   */
+  void scrollToHorizontalPosition(in long horizontalPosition);
+
+  /**
+   * Invalidation methods for fine-grained painting control.
+   */
+  void invalidate();
+  void invalidateColumn(in nsITreeColumn col);
+  void invalidateRow(in long index);
+  void invalidateCell(in long row, in nsITreeColumn col);
+  void invalidateRange(in long startIndex, in long endIndex);
+  void invalidateColumnRange(in long startIndex, in long endIndex,
+                             in nsITreeColumn col);
+
+  /**
+   * A hit test that can tell you what row the mouse is over.
+   * returns -1 for invalid mouse coordinates.
+   *
+   * The coordinate system is the client coordinate system for the
+   * document this boxObject lives in, and the units are CSS pixels.
+   */
+  long getRowAt(in long x, in long y);
+
+  /**
+   * A hit test that can tell you what cell the mouse is over.  Row is the row index
+   * hit,  returns -1 for invalid mouse coordinates.  ColID is the column hit.
+   * ChildElt is the pseudoelement hit: this can have values of
+   * "cell", "twisty", "image", and "text".
+   *
+   * The coordinate system is the client coordinate system for the
+   * document this boxObject lives in, and the units are CSS pixels.
+   */
+  void getCellAt(in long x, in long y, out long row, out nsITreeColumn col, out AString childElt);
+
+  /** 
+   * Find the coordinates of an element within a specific cell. 
+   */
+  void getCoordsForCellItem(in long row, in nsITreeColumn col, in AString element,
+                            out long x, out long y, out long width, out long height);
+
+  /** 
+   * Determine if the text of a cell is being cropped or not.
+   */
+  boolean isCellCropped(in long row, in nsITreeColumn col);
+
+  /**
+   * The view is responsible for calling these notification methods when
+   * rows are added or removed.  Index is the position at which the new
+   * rows were added or at which rows were removed.  For
+   * non-contiguous additions/removals, this method should be called multiple times.
+   */
+  void rowCountChanged(in long index, in long count);
+  
+  /**
+   * Notify the tree that the view is about to perform a batch
+   * update, that is, add, remove or invalidate several rows at once.
+   * This must be followed by calling endUpdateBatch(), otherwise the tree
+   * will get out of sync.
+   */
+  void beginUpdateBatch();
+
+  /**
+   * Notify the tree that the view has completed a batch update.
+   */
+  void endUpdateBatch();
+
+  /**
+   * Called on a theme switch to flush out the tree's style and image caches.
+   */
+  void clearStyleAndImageCaches();
+};
diff --git a/layout/xul/tree/nsITreeColumns.idl b/layout/xul/tree/nsITreeColumns.idl
new file mode 100644
index 0000000000..a601f3776b
--- /dev/null
+++ b/layout/xul/tree/nsITreeColumns.idl
@@ -0,0 +1,96 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsITreeColumns;
+interface nsIDOMElement;
+interface nsIAtom;
+
+[scriptable, uuid(ae835ecf-6b32-4660-9b43-8a270df56e02)]
+interface nsITreeColumn : nsISupports
+{
+  readonly attribute nsIDOMElement element;
+
+  readonly attribute nsITreeColumns columns;
+
+  readonly attribute long x;
+  readonly attribute long width;
+
+  readonly attribute AString id;
+  [noscript] void getIdConst([shared] out wstring idConst);
+  [noscript] readonly attribute nsIAtom atom;
+
+  readonly attribute long index;
+
+  readonly attribute boolean primary;
+  readonly attribute boolean cycler;
+  readonly attribute boolean editable;
+  readonly attribute boolean selectable;
+
+  const short TYPE_TEXT                = 1;
+  const short TYPE_CHECKBOX            = 2;
+  const short TYPE_PROGRESSMETER       = 3;
+  const short TYPE_PASSWORD            = 4;
+  readonly attribute short type;
+
+  nsITreeColumn getNext();
+  nsITreeColumn getPrevious();
+
+  void invalidate();
+};
+
+interface nsITreeBoxObject;
+
+[scriptable, uuid(f8a8d6b4-6788-438d-9009-7142798767ab)]
+interface nsITreeColumns : nsISupports
+{
+  /**
+   * The tree widget for these columns.
+   */
+  readonly attribute nsITreeBoxObject tree;
+
+  /**
+   * The number of columns.
+   */
+  readonly attribute long count;
+
+  /**
+   * An alias for count (for the benefit of scripts which treat this as an
+   * array).
+   */
+  readonly attribute long length;
+
+  /**
+   * Get the first/last column.
+   */
+  nsITreeColumn getFirstColumn();
+  nsITreeColumn getLastColumn();
+
+  /**
+   * Attribute based column getters.
+   */
+  nsITreeColumn getPrimaryColumn();
+  nsITreeColumn getSortedColumn();
+  nsITreeColumn getKeyColumn();
+
+  /**
+   * Get the column for the given element.
+   */
+  nsITreeColumn getColumnFor(in nsIDOMElement element);
+
+  /**
+   * Parametric column getters.
+   */
+  nsITreeColumn getNamedColumn(in AString id);
+  nsITreeColumn getColumnAt(in long index);
+
+  /**
+   * This method is called whenever a treecol is added or removed and
+   * the column cache needs to be rebuilt.
+   */
+  void invalidateColumns();
+
+  void restoreNaturalOrder();
+};
diff --git a/layout/xul/tree/nsITreeContentView.idl b/layout/xul/tree/nsITreeContentView.idl
new file mode 100644
index 0000000000..0b5d178aa3
--- /dev/null
+++ b/layout/xul/tree/nsITreeContentView.idl
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsIDOMElement;
+
+[scriptable, uuid(5ef62896-0c0a-41f1-bb3c-44a60f5dfdab)]
+interface nsITreeContentView : nsISupports
+{
+  /**
+   * Retrieve the content item associated with the specified index.
+   */
+  nsIDOMElement getItemAtIndex(in long index);
+
+  /**
+   * Retrieve the index associated with the specified content item.
+   */
+  long getIndexOfItem(in nsIDOMElement item);
+};
diff --git a/layout/xul/tree/nsITreeSelection.idl b/layout/xul/tree/nsITreeSelection.idl
new file mode 100644
index 0000000000..6cc137f1ef
--- /dev/null
+++ b/layout/xul/tree/nsITreeSelection.idl
@@ -0,0 +1,130 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+interface nsITreeBoxObject;
+interface nsITreeColumn;
+
+#include "nsISupports.idl"
+
+[scriptable, uuid(ab6fe746-300b-4ab4-abb9-1c0e3977874c)]
+interface nsITreeSelection : nsISupports
+{
+  /**
+   * The tree widget for this selection.
+   */
+  attribute nsITreeBoxObject tree;
+
+  /**
+   * This attribute is a boolean indicating single selection.
+   */
+  readonly attribute boolean single;
+
+  /**
+   * The number of rows currently selected in this tree.
+   */
+  readonly attribute long count;
+
+  /**
+   * Indicates whether or not the row at the specified index is
+   * part of the selection.
+   */
+  boolean isSelected(in long index);
+
+  /**
+   * Deselect all rows and select the row at the specified index. 
+   */
+  void select(in long index);
+
+  /**
+   * Perform a timed select.
+   */
+  void timedSelect(in long index, in long delay);
+
+  /**
+   * Toggle the selection state of the row at the specified index.
+   */
+  void toggleSelect(in long index);
+
+  /**
+   * Select the range specified by the indices.  If augment is true,
+   * then we add the range to the selection without clearing out anything
+   * else.  If augment is false, everything is cleared except for the specified range.
+   */
+  void rangedSelect(in long startIndex, in long endIndex, in boolean augment);
+
+  /**
+   * Clears the range.
+   */
+  void clearRange(in long startIndex, in long endIndex);
+
+  /**
+   * Clears the selection.
+   */
+  void clearSelection();
+
+  /**
+   * Inverts the selection.
+   */
+  void invertSelection();
+
+  /**
+   * Selects all rows.
+   */
+  void selectAll();
+
+  /**
+   * Iterate the selection using these methods.
+   */
+  long getRangeCount();
+  void getRangeAt(in long i, out long min, out long max);
+
+  /**
+   * Can be used to invalidate the selection.
+   */
+  void invalidateSelection();
+
+  /**
+   * Called when the row count changes to adjust selection indices.
+   */
+  void adjustSelection(in long index, in long count);
+
+  /**
+   * This attribute is a boolean indicating whether or not the
+   * "select" event should fire when the selection is changed using
+   * one of our methods.  A view can use this to temporarily suppress
+   * the selection while manipulating all of the indices, e.g., on 
+   * a sort.
+   * Note: setting this attribute to false will fire a select event.
+   */
+  attribute boolean selectEventsSuppressed;
+
+  /**
+   * The current item (the one that gets a focus rect in addition to being
+   * selected).
+   */
+  attribute long currentIndex;
+
+  /**
+   * The current column.
+   */
+  attribute nsITreeColumn currentColumn;
+
+  /**
+   * The selection "pivot".  This is the first item the user selected as
+   * part of a ranged select.
+   */
+  readonly attribute long shiftSelectPivot;
+};
+
+/**
+ * The following interface is not scriptable and MUST NEVER BE MADE scriptable.
+ * Native treeselections implement it, and we use this to check whether a
+ * treeselection is native (and therefore suitable for use by untrusted content).
+ */
+[uuid(1bd59678-5cb3-4316-b246-31a91b19aabe)]
+interface nsINativeTreeSelection : nsITreeSelection
+{
+  [noscript] void ensureNative();
+};
diff --git a/layout/xul/tree/nsITreeView.idl b/layout/xul/tree/nsITreeView.idl
new file mode 100644
index 0000000000..66920f81b7
--- /dev/null
+++ b/layout/xul/tree/nsITreeView.idl
@@ -0,0 +1,215 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+interface nsITreeBoxObject;
+interface nsITreeSelection;
+interface nsITreeColumn;
+interface nsIDOMDataTransfer;
+
+[scriptable, uuid(091116f0-0bdc-4b32-b9c8-c8d5a37cb088)]
+interface nsITreeView : nsISupports
+{
+  /**
+   * The total number of rows in the tree (including the offscreen rows).
+   */
+  readonly attribute long rowCount;
+
+  /**
+   * The selection for this view.
+   */
+  attribute nsITreeSelection selection;
+
+  /** 
+   * A whitespace delimited list of properties.  For each property X the view
+   * gives back will cause the pseudoclasses  ::-moz-tree-cell(x),
+   * ::-moz-tree-row(x), ::-moz-tree-twisty(x), ::-moz-tree-image(x),
+   * ::-moz-tree-cell-text(x).  to be matched on the pseudoelement
+   * ::moz-tree-row.
+   */
+  AString getRowProperties(in long index);
+
+  /**
+   * A whitespace delimited list of properties for a given cell.  Each
+   * property, x, that the view gives back will cause the pseudoclasses
+   *  ::-moz-tree-cell(x), ::-moz-tree-row(x), ::-moz-tree-twisty(x),
+   *  ::-moz-tree-image(x), ::-moz-tree-cell-text(x). to be matched on the
+   *  cell.
+   */
+  AString getCellProperties(in long row, in nsITreeColumn col);
+  
+  /**
+   * Called to get properties to paint a column background.  For shading the sort
+   * column, etc.
+   */
+  AString getColumnProperties(in nsITreeColumn col);
+
+  /**
+   * Methods that can be used to test whether or not a twisty should be drawn,
+   * and if so, whether an open or closed twisty should be used.
+   */
+  boolean isContainer(in long index);
+  boolean isContainerOpen(in long index);
+  boolean isContainerEmpty(in long index);
+ 
+  /**
+   * isSeparator is used to determine if the row at index is a separator.
+   * A value of true will result in the tree drawing a horizontal separator.
+   * The tree uses the ::moz-tree-separator pseudoclass to draw the separator.
+   */
+  boolean isSeparator(in long index);
+
+  /**
+   * Specifies if there is currently a sort on any column. Used mostly by dragdrop
+   * to affect drop feedback.
+   */
+  boolean isSorted();
+  
+  const short DROP_BEFORE = -1;
+  const short DROP_ON = 0;
+  const short DROP_AFTER = 1;
+  /**
+   * Methods used by the drag feedback code to determine if a drag is allowable at
+   * the current location. To get the behavior where drops are only allowed on
+   * items, such as the mailNews folder pane, always return false when
+   * the orientation is not DROP_ON.
+   */
+  boolean canDrop(in long index, in long orientation, in nsIDOMDataTransfer dataTransfer);
+
+  /**
+   * Called when the user drops something on this view. The |orientation| param
+   * specifies before/on/after the given |row|.
+   */
+  void drop(in long row, in long orientation, in nsIDOMDataTransfer dataTransfer);
+
+  /**
+   * Methods used by the tree to draw thread lines in the tree.
+   * getParentIndex is used to obtain the index of a parent row.
+   * If there is no parent row, getParentIndex returns -1.
+   */
+  long getParentIndex(in long rowIndex);
+
+  /**
+   * hasNextSibling is used to determine if the row at rowIndex has a nextSibling
+   * that occurs *after* the index specified by afterIndex.  Code that is forced
+   * to march down the view looking at levels can optimize the march by starting
+   * at afterIndex+1.
+   */
+  boolean hasNextSibling(in long rowIndex, in long afterIndex);
+
+  /**
+   * The level is an integer value that represents
+   * the level of indentation.  It is multiplied by the width specified in the 
+   * :moz-tree-indentation pseudoelement to compute the exact indendation.
+   */
+  long getLevel(in long index);
+
+  /**
+   * The image path for a given cell. For defining an icon for a cell.
+   * If the empty string is returned, the :moz-tree-image pseudoelement
+   * will be used.
+   */
+  AString getImageSrc(in long row, in nsITreeColumn col);
+
+  /**
+   * The progress mode for a given cell. This method is only called for
+   * columns of type |progressmeter|.
+   */
+  const short PROGRESS_NORMAL = 1;
+  const short PROGRESS_UNDETERMINED = 2;
+  const short PROGRESS_NONE = 3;
+  long getProgressMode(in long row, in nsITreeColumn col);
+
+  /**
+   * The value for a given cell. This method is only called for columns
+   * of type other than |text|.
+   */
+  AString getCellValue(in long row, in nsITreeColumn col);
+
+  /**
+   * The text for a given cell.  If a column consists only of an image, then
+   * the empty string is returned.  
+   */
+  AString getCellText(in long row, in nsITreeColumn col);
+
+  /**
+   * Called during initialization to link the view to the front end box object.
+   */
+  void setTree(in nsITreeBoxObject tree);
+  
+  /**
+   * Called on the view when an item is opened or closed.
+   */
+  void toggleOpenState(in long index);
+
+  /**
+   * Called on the view when a header is clicked.
+   */
+  void cycleHeader(in nsITreeColumn col);
+
+  /**
+   * Should be called from a XUL onselect handler whenever the selection changes.
+   */
+  void selectionChanged();
+
+  /**
+   * Called on the view when a cell in a non-selectable cycling column (e.g., unread/flag/etc.) is clicked.
+   */
+  void cycleCell(in long row, in nsITreeColumn col);
+  
+  /**
+   * isEditable is called to ask the view if the cell contents are editable.
+   * A value of true will result in the tree popping up a text field when 
+   * the user tries to inline edit the cell.
+   */
+  boolean isEditable(in long row, in nsITreeColumn col);
+
+  /**
+   * isSelectable is called to ask the view if the cell is selectable.
+   * This method is only called if the selection style is |cell| or |text|.
+   * XXXvarga shouldn't this be called isCellSelectable?
+   */
+  boolean isSelectable(in long row, in nsITreeColumn col);
+
+  /**
+   * setCellValue is called when the value of the cell has been set by the user.
+   * This method is only called for columns of type other than |text|.
+   */
+  void setCellValue(in long row, in nsITreeColumn col, in AString value);
+
+  /**
+   * setCellText is called when the contents of the cell have been edited by the user.
+   */   
+  void setCellText(in long row, in nsITreeColumn col, in AString value);
+
+  /**
+   * A command API that can be used to invoke commands on the selection.  The tree
+   * will automatically invoke this method when certain keys are pressed.  For example,
+   * when the DEL key is pressed, performAction will be called with the "delete" string.
+   */
+  void performAction(in wstring action);
+
+  /**
+   * A command API that can be used to invoke commands on a specific row.
+   */
+  void performActionOnRow(in wstring action, in long row);
+
+  /**
+   * A command API that can be used to invoke commands on a specific cell.
+   */
+  void performActionOnCell(in wstring action, in long row, in nsITreeColumn col);
+};
+
+/**
+ * The following interface is not scriptable and MUST NEVER BE MADE scriptable.
+ * Native treeviews implement it, and we use this to check whether a treeview
+ * is native (and therefore suitable for use by untrusted content).
+ */
+[uuid(46c90265-6553-41ae-8d39-7022e7d09145)]
+interface nsINativeTreeView : nsITreeView
+{
+  [noscript] void ensureNative();
+};
diff --git a/layout/xul/tree/nsTreeBodyFrame.cpp b/layout/xul/tree/nsTreeBodyFrame.cpp
new file mode 100644
index 0000000000..deba04a36c
--- /dev/null
+++ b/layout/xul/tree/nsTreeBodyFrame.cpp
@@ -0,0 +1,4945 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/AsyncEventDispatcher.h"
+#include "mozilla/ContentEvents.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/PathHelpers.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/TextEditRules.h"
+
+#include "gfxUtils.h"
+#include "nsAlgorithm.h"
+#include "nsCOMPtr.h"
+#include "nsFontMetrics.h"
+#include "nsPresContext.h"
+#include "nsNameSpaceManager.h"
+
+#include "nsTreeBodyFrame.h"
+#include "nsTreeSelection.h"
+#include "nsTreeImageListener.h"
+
+#include "nsGkAtoms.h"
+#include "nsCSSAnonBoxes.h"
+
+#include "nsIContent.h"
+#include "nsStyleContext.h"
+#include "nsIBoxObject.h"
+#include "nsIDOMCustomEvent.h"
+#include "nsIDOMMouseEvent.h"
+#include "nsIDOMElement.h"
+#include "nsIDOMNodeList.h"
+#include "nsIDOMDocument.h"
+#include "nsIDOMXULElement.h"
+#include "nsIDocument.h"
+#include "mozilla/css/StyleRule.h"
+#include "nsCSSRendering.h"
+#include "nsIXULTemplateBuilder.h"
+#include "nsXPIDLString.h"
+#include "nsContainerFrame.h"
+#include "nsView.h"
+#include "nsViewManager.h"
+#include "nsVariant.h"
+#include "nsWidgetsCID.h"
+#include "nsBoxFrame.h"
+#include "nsIURL.h"
+#include "nsBoxLayoutState.h"
+#include "nsTreeContentView.h"
+#include "nsTreeUtils.h"
+#include "nsThemeConstants.h"
+#include "nsITheme.h"
+#include "imgIRequest.h"
+#include "imgIContainer.h"
+#include "imgILoader.h"
+#include "mozilla/dom/NodeInfo.h"
+#include "nsContentUtils.h"
+#include "nsLayoutUtils.h"
+#include "nsIScrollableFrame.h"
+#include "nsDisplayList.h"
+#include "mozilla/dom/TreeBoxObject.h"
+#include "nsRenderingContext.h"
+#include "nsIScriptableRegion.h"
+#include <algorithm>
+#include "ScrollbarActivity.h"
+
+#ifdef ACCESSIBILITY
+#include "nsAccessibilityService.h"
+#include "nsIWritablePropertyBag2.h"
+#endif
+#include "nsBidiUtils.h"
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+using namespace mozilla::image;
+using namespace mozilla::layout;
+
+// Function that cancels all the image requests in our cache.
+void
+nsTreeBodyFrame::CancelImageRequests()
+{
+  for (auto iter = mImageCache.Iter(); !iter.Done(); iter.Next()) {
+    // If our imgIRequest object was registered with the refresh driver
+    // then we need to deregister it.
+    nsTreeImageCacheEntry entry = iter.UserData();
+    nsLayoutUtils::DeregisterImageRequest(PresContext(), entry.request,
+                                          nullptr);
+    entry.request->CancelAndForgetObserver(NS_BINDING_ABORTED);
+  }
+}
+
+//
+// NS_NewTreeFrame
+//
+// Creates a new tree frame
+//
+nsIFrame*
+NS_NewTreeBodyFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsTreeBodyFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsTreeBodyFrame)
+
+NS_QUERYFRAME_HEAD(nsTreeBodyFrame)
+  NS_QUERYFRAME_ENTRY(nsIScrollbarMediator)
+  NS_QUERYFRAME_ENTRY(nsTreeBodyFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsLeafBoxFrame)
+
+// Constructor
+nsTreeBodyFrame::nsTreeBodyFrame(nsStyleContext* aContext)
+:nsLeafBoxFrame(aContext),
+ mSlots(nullptr),
+ mImageCache(),
+ mTopRowIndex(0),
+ mPageLength(0),
+ mHorzPosition(0),
+ mOriginalHorzWidth(-1),
+ mHorzWidth(0),
+ mAdjustWidth(0),
+ mRowHeight(0),
+ mIndentation(0),
+ mStringWidth(-1),
+ mUpdateBatchNest(0),
+ mRowCount(0),
+ mMouseOverRow(-1),
+ mFocused(false),
+ mHasFixedRowCount(false),
+ mVerticalOverflow(false),
+ mHorizontalOverflow(false),
+ mReflowCallbackPosted(false),
+ mCheckingOverflow(false)
+{
+  mColumns = new nsTreeColumns(this);
+}
+
+// Destructor
+nsTreeBodyFrame::~nsTreeBodyFrame()
+{
+  CancelImageRequests();
+  DetachImageListeners();
+  delete mSlots;
+}
+
+static void
+GetBorderPadding(nsStyleContext* aContext, nsMargin& aMargin)
+{
+  aMargin.SizeTo(0, 0, 0, 0);
+  aContext->StylePadding()->GetPadding(aMargin);
+  aMargin += aContext->StyleBorder()->GetComputedBorder();
+}
+
+static void
+AdjustForBorderPadding(nsStyleContext* aContext, nsRect& aRect)
+{
+  nsMargin borderPadding(0, 0, 0, 0);
+  GetBorderPadding(aContext, borderPadding);
+  aRect.Deflate(borderPadding);
+}
+
+void
+nsTreeBodyFrame::Init(nsIContent*       aContent,
+                      nsContainerFrame* aParent,
+                      nsIFrame*         aPrevInFlow)
+{
+  nsLeafBoxFrame::Init(aContent, aParent, aPrevInFlow);
+
+  mIndentation = GetIndentation();
+  mRowHeight = GetRowHeight();
+
+  EnsureBoxObject();
+
+  if (LookAndFeel::GetInt(LookAndFeel::eIntID_UseOverlayScrollbars) != 0) {
+    mScrollbarActivity = new ScrollbarActivity(
+                           static_cast<nsIScrollbarMediator*>(this));
+  }
+}
+
+nsSize
+nsTreeBodyFrame::GetXULMinSize(nsBoxLayoutState& aBoxLayoutState)
+{
+  EnsureView();
+
+  nsIContent* baseElement = GetBaseElement();
+
+  nsSize min(0,0);
+  int32_t desiredRows;
+  if (MOZ_UNLIKELY(!baseElement)) {
+    desiredRows = 0;
+  }
+  else if (baseElement->IsHTMLElement(nsGkAtoms::select)) {
+    min.width = CalcMaxRowWidth();
+    nsAutoString size;
+    baseElement->GetAttr(kNameSpaceID_None, nsGkAtoms::size, size);
+    if (!size.IsEmpty()) {
+      nsresult err;
+      desiredRows = size.ToInteger(&err);
+      mHasFixedRowCount = true;
+      mPageLength = desiredRows;
+    }
+    else {
+      desiredRows = 1;
+    }
+  }
+  else {
+    // tree
+    nsAutoString rows;
+    baseElement->GetAttr(kNameSpaceID_None, nsGkAtoms::rows, rows);
+    if (!rows.IsEmpty()) {
+      nsresult err;
+      desiredRows = rows.ToInteger(&err);
+      mPageLength = desiredRows;
+    }
+    else {
+      desiredRows = 0;
+    }
+  }
+
+  min.height = mRowHeight * desiredRows;
+
+  AddBorderAndPadding(min);
+  bool widthSet, heightSet;
+  nsIFrame::AddXULMinSize(aBoxLayoutState, this, min, widthSet, heightSet);
+
+  return min;
+}
+
+nscoord
+nsTreeBodyFrame::CalcMaxRowWidth()
+{
+  if (mStringWidth != -1)
+    return mStringWidth;
+
+  if (!mView)
+    return 0;
+
+  nsStyleContext* rowContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreerow);
+  nsMargin rowMargin(0,0,0,0);
+  GetBorderPadding(rowContext, rowMargin);
+
+  nscoord rowWidth;
+  nsTreeColumn* col;
+
+  nsRenderingContext rc(
+    PresContext()->PresShell()->CreateReferenceRenderingContext());
+
+  for (int32_t row = 0; row < mRowCount; ++row) {
+    rowWidth = 0;
+
+    for (col = mColumns->GetFirstColumn(); col; col = col->GetNext()) {
+      nscoord desiredWidth, currentWidth;
+      nsresult rv = GetCellWidth(row, col, &rc, desiredWidth, currentWidth);
+      if (NS_FAILED(rv)) {
+        NS_NOTREACHED("invalid column");
+        continue;
+      }
+      rowWidth += desiredWidth;
+    }
+
+    if (rowWidth > mStringWidth)
+      mStringWidth = rowWidth;
+  }
+
+  mStringWidth += rowMargin.left + rowMargin.right;
+  return mStringWidth;
+}
+
+void
+nsTreeBodyFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  if (mScrollbarActivity) {
+    mScrollbarActivity->Destroy();
+    mScrollbarActivity = nullptr;
+  }
+
+  mScrollEvent.Revoke();
+  // Make sure we cancel any posted callbacks. 
+  if (mReflowCallbackPosted) {
+    PresContext()->PresShell()->CancelReflowCallback(this);
+    mReflowCallbackPosted = false;
+  }
+
+  if (mColumns)
+    mColumns->SetTree(nullptr);
+
+  // Save off our info into the box object.
+  nsCOMPtr<nsPIBoxObject> box(do_QueryInterface(mTreeBoxObject));
+  if (box) {
+    if (mTopRowIndex > 0) {
+      nsAutoString topRowStr; topRowStr.AssignLiteral("topRow");
+      nsAutoString topRow;
+      topRow.AppendInt(mTopRowIndex);
+      box->SetProperty(topRowStr.get(), topRow.get());
+    }
+
+    // Always null out the cached tree body frame.
+    box->ClearCachedValues();
+
+    mTreeBoxObject = nullptr; // Drop our ref here.
+  }
+
+  if (mView) {
+    nsCOMPtr<nsITreeSelection> sel;
+    mView->GetSelection(getter_AddRefs(sel));
+    if (sel)
+      sel->SetTree(nullptr);
+    mView->SetTree(nullptr);
+    mView = nullptr;
+  }
+
+  nsLeafBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+void
+nsTreeBodyFrame::EnsureBoxObject()
+{
+  if (!mTreeBoxObject) {
+    nsIContent* parent = GetBaseElement();
+    if (parent) {
+      nsIDocument* nsDoc = parent->GetComposedDoc();
+      if (!nsDoc) // there may be no document, if we're called from Destroy()
+        return;
+      ErrorResult ignored;
+      nsCOMPtr<nsIBoxObject> box =
+        nsDoc->GetBoxObjectFor(parent->AsElement(), ignored);
+      // Ensure that we got a native box object.
+      nsCOMPtr<nsPIBoxObject> pBox = do_QueryInterface(box);
+      if (pBox) {
+        nsCOMPtr<nsITreeBoxObject> realTreeBoxObject = do_QueryInterface(pBox);
+        if (realTreeBoxObject) {
+          nsTreeBodyFrame* innerTreeBoxObject =
+            static_cast<dom::TreeBoxObject*>(realTreeBoxObject.get())
+              ->GetCachedTreeBodyFrame();
+          ENSURE_TRUE(!innerTreeBoxObject || innerTreeBoxObject == this);
+          mTreeBoxObject = realTreeBoxObject;
+        }
+      }
+    }
+  }
+}
+
+void
+nsTreeBodyFrame::EnsureView()
+{
+  if (!mView) {
+    if (PresContext()->PresShell()->IsReflowLocked()) {
+      if (!mReflowCallbackPosted) {
+        mReflowCallbackPosted = true;
+        PresContext()->PresShell()->PostReflowCallback(this);
+      }
+      return;
+    }
+    nsCOMPtr<nsIBoxObject> box = do_QueryInterface(mTreeBoxObject);
+    if (box) {
+      nsWeakFrame weakFrame(this);
+      nsCOMPtr<nsITreeView> treeView;
+      mTreeBoxObject->GetView(getter_AddRefs(treeView));
+      if (treeView && weakFrame.IsAlive()) {
+        nsXPIDLString rowStr;
+        box->GetProperty(u"topRow", getter_Copies(rowStr));
+        nsAutoString rowStr2(rowStr);
+        nsresult error;
+        int32_t rowIndex = rowStr2.ToInteger(&error);
+
+        // Set our view.
+        SetView(treeView);
+        ENSURE_TRUE(weakFrame.IsAlive());
+
+        // Scroll to the given row.
+        // XXX is this optimal if we haven't laid out yet?
+        ScrollToRow(rowIndex);
+        ENSURE_TRUE(weakFrame.IsAlive());
+
+        // Clear out the property info for the top row, but we always keep the
+        // view current.
+        box->RemoveProperty(u"topRow");
+      }
+    }
+  }
+}
+
+void
+nsTreeBodyFrame::ManageReflowCallback(const nsRect& aRect, nscoord aHorzWidth)
+{
+  if (!mReflowCallbackPosted &&
+      (!aRect.IsEqualEdges(mRect) || mHorzWidth != aHorzWidth)) {
+    PresContext()->PresShell()->PostReflowCallback(this);
+    mReflowCallbackPosted = true;
+    mOriginalHorzWidth = mHorzWidth;
+  }
+  else if (mReflowCallbackPosted &&
+           mHorzWidth != aHorzWidth && mOriginalHorzWidth == aHorzWidth) {
+    PresContext()->PresShell()->CancelReflowCallback(this);
+    mReflowCallbackPosted = false;
+    mOriginalHorzWidth = -1;
+  }
+}
+
+void
+nsTreeBodyFrame::SetXULBounds(nsBoxLayoutState& aBoxLayoutState, const nsRect& aRect,
+                              bool aRemoveOverflowArea)
+{
+  nscoord horzWidth = CalcHorzWidth(GetScrollParts());
+  ManageReflowCallback(aRect, horzWidth);
+  mHorzWidth = horzWidth;
+
+  nsLeafBoxFrame::SetXULBounds(aBoxLayoutState, aRect, aRemoveOverflowArea);
+}
+
+
+bool
+nsTreeBodyFrame::ReflowFinished()
+{
+  if (!mView) {
+    nsWeakFrame weakFrame(this);
+    EnsureView();
+    NS_ENSURE_TRUE(weakFrame.IsAlive(), false);
+  }
+  if (mView) {
+    CalcInnerBox();
+    ScrollParts parts = GetScrollParts();
+    mHorzWidth = CalcHorzWidth(parts);
+    if (!mHasFixedRowCount) {
+      mPageLength = mInnerBox.height / mRowHeight;
+    }
+
+    int32_t lastPageTopRow = std::max(0, mRowCount - mPageLength);
+    if (mTopRowIndex > lastPageTopRow)
+      ScrollToRowInternal(parts, lastPageTopRow);
+
+    nsIContent *treeContent = GetBaseElement();
+    if (treeContent &&
+        treeContent->AttrValueIs(kNameSpaceID_None,
+                                 nsGkAtoms::keepcurrentinview,
+                                 nsGkAtoms::_true, eCaseMatters)) {
+      // make sure that the current selected item is still
+      // visible after the tree changes size.
+      nsCOMPtr<nsITreeSelection> sel;
+      mView->GetSelection(getter_AddRefs(sel));
+      if (sel) {
+        int32_t currentIndex;
+        sel->GetCurrentIndex(&currentIndex);
+        if (currentIndex != -1)
+          EnsureRowIsVisibleInternal(parts, currentIndex);
+      }
+    }
+
+    if (!FullScrollbarsUpdate(false)) {
+      return false;
+    }
+  }
+
+  mReflowCallbackPosted = false;
+  return false;
+}
+
+void
+nsTreeBodyFrame::ReflowCallbackCanceled()
+{
+  mReflowCallbackPosted = false;
+}
+
+nsresult
+nsTreeBodyFrame::GetView(nsITreeView * *aView)
+{
+  *aView = nullptr;
+  nsWeakFrame weakFrame(this);
+  EnsureView();
+  NS_ENSURE_STATE(weakFrame.IsAlive());
+  NS_IF_ADDREF(*aView = mView);
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::SetView(nsITreeView * aView)
+{
+  // First clear out the old view.
+  if (mView) {
+    nsCOMPtr<nsITreeSelection> sel;
+    mView->GetSelection(getter_AddRefs(sel));
+    if (sel)
+      sel->SetTree(nullptr);
+    mView->SetTree(nullptr);
+
+    // Only reset the top row index and delete the columns if we had an old non-null view.
+    mTopRowIndex = 0;
+  }
+
+  // Tree, meet the view.
+  mView = aView;
+ 
+  // Changing the view causes us to refetch our data.  This will
+  // necessarily entail a full invalidation of the tree.
+  Invalidate();
+ 
+  nsIContent *treeContent = GetBaseElement();
+  if (treeContent) {
+#ifdef ACCESSIBILITY
+    nsAccessibilityService* accService = nsIPresShell::AccService();
+    if (accService)
+      accService->TreeViewChanged(PresContext()->GetPresShell(), treeContent, mView);
+#endif
+    FireDOMEvent(NS_LITERAL_STRING("TreeViewChanged"), treeContent);
+  }
+
+  if (mView) {
+    // Give the view a new empty selection object to play with, but only if it
+    // doesn't have one already.
+    nsCOMPtr<nsITreeSelection> sel;
+    mView->GetSelection(getter_AddRefs(sel));
+    if (sel) {
+      sel->SetTree(mTreeBoxObject);
+    }
+    else {
+      NS_NewTreeSelection(mTreeBoxObject, getter_AddRefs(sel));
+      mView->SetSelection(sel);
+    }
+
+    // View, meet the tree.
+    nsWeakFrame weakFrame(this);
+    mView->SetTree(mTreeBoxObject);
+    NS_ENSURE_STATE(weakFrame.IsAlive());
+    mView->GetRowCount(&mRowCount);
+ 
+    if (!PresContext()->PresShell()->IsReflowLocked()) {
+      // The scrollbar will need to be updated.
+      FullScrollbarsUpdate(false);
+    } else if (!mReflowCallbackPosted) {
+      mReflowCallbackPosted = true;
+      PresContext()->PresShell()->PostReflowCallback(this);
+    }
+  }
+ 
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::SetFocused(bool aFocused)
+{
+  if (mFocused != aFocused) {
+    mFocused = aFocused;
+    if (mView) {
+      nsCOMPtr<nsITreeSelection> sel;
+      mView->GetSelection(getter_AddRefs(sel));
+      if (sel)
+        sel->InvalidateSelection();
+    }
+  }
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::GetTreeBody(nsIDOMElement** aElement)
+{
+  //NS_ASSERTION(mContent, "no content, see bug #104878");
+  if (!mContent)
+    return NS_ERROR_NULL_POINTER;
+
+  return mContent->QueryInterface(NS_GET_IID(nsIDOMElement), (void**)aElement);
+}
+
+int32_t
+nsTreeBodyFrame::RowHeight() const
+{
+  return nsPresContext::AppUnitsToIntCSSPixels(mRowHeight);
+}
+
+int32_t
+nsTreeBodyFrame::RowWidth()
+{
+  return nsPresContext::AppUnitsToIntCSSPixels(CalcHorzWidth(GetScrollParts()));
+}
+
+int32_t
+nsTreeBodyFrame::GetHorizontalPosition() const
+{
+  return nsPresContext::AppUnitsToIntCSSPixels(mHorzPosition);
+}
+
+nsresult
+nsTreeBodyFrame::GetSelectionRegion(nsIScriptableRegion **aRegion)
+{
+  *aRegion = nullptr;
+
+  nsCOMPtr<nsITreeSelection> selection;
+  mView->GetSelection(getter_AddRefs(selection));
+  NS_ENSURE_TRUE(selection, NS_OK);
+
+  nsCOMPtr<nsIScriptableRegion> region = do_CreateInstance("@mozilla.org/gfx/region;1");
+  NS_ENSURE_TRUE(region, NS_ERROR_FAILURE);
+  region->Init();
+
+  RefPtr<nsPresContext> presContext = PresContext();
+  nsIntRect rect = mRect.ToOutsidePixels(presContext->AppUnitsPerCSSPixel());
+
+  nsIFrame* rootFrame = presContext->PresShell()->GetRootFrame();
+  nsPoint origin = GetOffsetTo(rootFrame);
+
+  // iterate through the visible rows and add the selected ones to the
+  // drag region
+  int32_t x = nsPresContext::AppUnitsToIntCSSPixels(origin.x);
+  int32_t y = nsPresContext::AppUnitsToIntCSSPixels(origin.y);
+  int32_t top = y;
+  int32_t end = LastVisibleRow();
+  int32_t rowHeight = nsPresContext::AppUnitsToIntCSSPixels(mRowHeight);
+  for (int32_t i = mTopRowIndex; i <= end; i++) {
+    bool isSelected;
+    selection->IsSelected(i, &isSelected);
+    if (isSelected)
+      region->UnionRect(x, y, rect.width, rowHeight);
+    y += rowHeight;
+  }
+
+  // clip to the tree boundary in case one row extends past it
+  region->IntersectRect(x, top, rect.width, rect.height);
+
+  region.forget(aRegion);
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::Invalidate()
+{
+  if (mUpdateBatchNest)
+    return NS_OK;
+
+  InvalidateFrame();
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::InvalidateColumn(nsITreeColumn* aCol)
+{
+  if (mUpdateBatchNest)
+    return NS_OK;
+
+  RefPtr<nsTreeColumn> col = GetColumnImpl(aCol);
+  if (!col)
+    return NS_ERROR_INVALID_ARG;
+
+#ifdef ACCESSIBILITY
+  if (nsIPresShell::IsAccessibilityActive())
+    FireInvalidateEvent(-1, -1, aCol, aCol);
+#endif
+
+  nsRect columnRect;
+  nsresult rv = col->GetRect(this, mInnerBox.y, mInnerBox.height, &columnRect);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // When false then column is out of view
+  if (OffsetForHorzScroll(columnRect, true))
+      InvalidateFrameWithRect(columnRect);
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::InvalidateRow(int32_t aIndex)
+{
+  if (mUpdateBatchNest)
+    return NS_OK;
+
+#ifdef ACCESSIBILITY
+  if (nsIPresShell::IsAccessibilityActive())
+    FireInvalidateEvent(aIndex, aIndex, nullptr, nullptr);
+#endif
+
+  aIndex -= mTopRowIndex;
+  if (aIndex < 0 || aIndex > mPageLength)
+    return NS_OK;
+
+  nsRect rowRect(mInnerBox.x, mInnerBox.y+mRowHeight*aIndex, mInnerBox.width, mRowHeight);
+  InvalidateFrameWithRect(rowRect);
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::InvalidateCell(int32_t aIndex, nsITreeColumn* aCol)
+{
+  if (mUpdateBatchNest)
+    return NS_OK;
+
+#ifdef ACCESSIBILITY
+  if (nsIPresShell::IsAccessibilityActive())
+    FireInvalidateEvent(aIndex, aIndex, aCol, aCol);
+#endif
+
+  aIndex -= mTopRowIndex;
+  if (aIndex < 0 || aIndex > mPageLength)
+    return NS_OK;
+
+  RefPtr<nsTreeColumn> col = GetColumnImpl(aCol);
+  if (!col)
+    return NS_ERROR_INVALID_ARG;
+
+  nsRect cellRect;
+  nsresult rv = col->GetRect(this, mInnerBox.y+mRowHeight*aIndex, mRowHeight,
+                             &cellRect);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (OffsetForHorzScroll(cellRect, true))
+    InvalidateFrameWithRect(cellRect);
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::InvalidateRange(int32_t aStart, int32_t aEnd)
+{
+  if (mUpdateBatchNest)
+    return NS_OK;
+
+  if (aStart == aEnd)
+    return InvalidateRow(aStart);
+
+  int32_t last = LastVisibleRow();
+  if (aStart > aEnd || aEnd < mTopRowIndex || aStart > last)
+    return NS_OK;
+
+  if (aStart < mTopRowIndex)
+    aStart = mTopRowIndex;
+
+  if (aEnd > last)
+    aEnd = last;
+
+#ifdef ACCESSIBILITY
+  if (nsIPresShell::IsAccessibilityActive()) {
+    int32_t end =
+      mRowCount > 0 ? ((mRowCount <= aEnd) ? mRowCount - 1 : aEnd) : 0;
+    FireInvalidateEvent(aStart, end, nullptr, nullptr);
+  }
+#endif
+
+  nsRect rangeRect(mInnerBox.x, mInnerBox.y+mRowHeight*(aStart-mTopRowIndex), mInnerBox.width, mRowHeight*(aEnd-aStart+1));
+  InvalidateFrameWithRect(rangeRect);
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::InvalidateColumnRange(int32_t aStart, int32_t aEnd, nsITreeColumn* aCol)
+{
+  if (mUpdateBatchNest)
+    return NS_OK;
+
+  RefPtr<nsTreeColumn> col = GetColumnImpl(aCol);
+  if (!col)
+    return NS_ERROR_INVALID_ARG;
+
+  if (aStart == aEnd)
+    return InvalidateCell(aStart, col);
+
+  int32_t last = LastVisibleRow();
+  if (aStart > aEnd || aEnd < mTopRowIndex || aStart > last)
+    return NS_OK;
+
+  if (aStart < mTopRowIndex)
+    aStart = mTopRowIndex;
+
+  if (aEnd > last)
+    aEnd = last;
+
+#ifdef ACCESSIBILITY
+  if (nsIPresShell::IsAccessibilityActive()) {
+    int32_t end =
+      mRowCount > 0 ? ((mRowCount <= aEnd) ? mRowCount - 1 : aEnd) : 0;
+    FireInvalidateEvent(aStart, end, aCol, aCol);
+  }
+#endif
+
+  nsRect rangeRect;
+  nsresult rv = col->GetRect(this, 
+                             mInnerBox.y+mRowHeight*(aStart-mTopRowIndex),
+                             mRowHeight*(aEnd-aStart+1),
+                             &rangeRect);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  InvalidateFrameWithRect(rangeRect);
+
+  return NS_OK;
+}
+
+static void
+FindScrollParts(nsIFrame* aCurrFrame, nsTreeBodyFrame::ScrollParts* aResult)
+{
+  if (!aResult->mColumnsScrollFrame) {
+    nsIScrollableFrame* f = do_QueryFrame(aCurrFrame);
+    if (f) {
+      aResult->mColumnsFrame = aCurrFrame;
+      aResult->mColumnsScrollFrame = f;
+    }
+  }
+  
+  nsScrollbarFrame *sf = do_QueryFrame(aCurrFrame);
+  if (sf) {
+    if (!aCurrFrame->IsXULHorizontal()) {
+      if (!aResult->mVScrollbar) {
+        aResult->mVScrollbar = sf;
+      }
+    } else {
+      if (!aResult->mHScrollbar) {
+        aResult->mHScrollbar = sf;
+      }
+    }
+    // don't bother searching inside a scrollbar
+    return;
+  }
+  
+  nsIFrame* child = aCurrFrame->PrincipalChildList().FirstChild();
+  while (child &&
+         !child->GetContent()->IsRootOfNativeAnonymousSubtree() &&
+         (!aResult->mVScrollbar || !aResult->mHScrollbar ||
+          !aResult->mColumnsScrollFrame)) {
+    FindScrollParts(child, aResult);
+    child = child->GetNextSibling();
+  }
+}
+
+nsTreeBodyFrame::ScrollParts nsTreeBodyFrame::GetScrollParts()
+{
+  ScrollParts result = { nullptr, nullptr, nullptr, nullptr, nullptr, nullptr };
+  nsIContent* baseElement = GetBaseElement();
+  nsIFrame* treeFrame =
+    baseElement ? baseElement->GetPrimaryFrame() : nullptr;
+  if (treeFrame) {
+    // The way we do this, searching through the entire frame subtree, is pretty
+    // dumb! We should know where these frames are.
+    FindScrollParts(treeFrame, &result);
+    if (result.mHScrollbar) {
+      result.mHScrollbar->SetScrollbarMediatorContent(GetContent());
+      nsIFrame* f = do_QueryFrame(result.mHScrollbar);
+      result.mHScrollbarContent = f->GetContent();
+    }
+    if (result.mVScrollbar) {
+      result.mVScrollbar->SetScrollbarMediatorContent(GetContent());
+      nsIFrame* f = do_QueryFrame(result.mVScrollbar);
+      result.mVScrollbarContent = f->GetContent();
+    }
+  }
+  return result;
+}
+
+void
+nsTreeBodyFrame::UpdateScrollbars(const ScrollParts& aParts)
+{
+  nscoord rowHeightAsPixels = nsPresContext::AppUnitsToIntCSSPixels(mRowHeight);
+
+  nsWeakFrame weakFrame(this);
+
+  if (aParts.mVScrollbar) {
+    nsAutoString curPos;
+    curPos.AppendInt(mTopRowIndex*rowHeightAsPixels);
+    aParts.mVScrollbarContent->
+      SetAttr(kNameSpaceID_None, nsGkAtoms::curpos, curPos, true);
+    // 'this' might be deleted here
+  }
+
+  if (weakFrame.IsAlive() && aParts.mHScrollbar) {
+    nsAutoString curPos;
+    curPos.AppendInt(mHorzPosition);
+    aParts.mHScrollbarContent->
+      SetAttr(kNameSpaceID_None, nsGkAtoms::curpos, curPos, true);
+    // 'this' might be deleted here
+  }
+
+  if (weakFrame.IsAlive() && mScrollbarActivity) {
+    mScrollbarActivity->ActivityOccurred();
+  }
+}
+
+void
+nsTreeBodyFrame::CheckOverflow(const ScrollParts& aParts)
+{
+  bool verticalOverflowChanged = false;
+  bool horizontalOverflowChanged = false;
+
+  if (!mVerticalOverflow && mRowCount > mPageLength) {
+    mVerticalOverflow = true;
+    verticalOverflowChanged = true;
+  }
+  else if (mVerticalOverflow && mRowCount <= mPageLength) {
+    mVerticalOverflow = false;
+    verticalOverflowChanged = true;
+  }
+
+  if (aParts.mColumnsFrame) {
+    nsRect bounds = aParts.mColumnsFrame->GetRect();
+    if (bounds.width != 0) {
+      /* Ignore overflows that are less than half a pixel. Yes these happen
+         all over the place when flex boxes are compressed real small. 
+         Probably a result of a rounding errors somewhere in the layout code. */
+      bounds.width += nsPresContext::CSSPixelsToAppUnits(0.5f);
+      if (!mHorizontalOverflow && bounds.width < mHorzWidth) {
+        mHorizontalOverflow = true;
+        horizontalOverflowChanged = true;
+      } else if (mHorizontalOverflow && bounds.width >= mHorzWidth) {
+        mHorizontalOverflow = false;
+        horizontalOverflowChanged = true;
+      }
+    }
+  }
+
+  nsWeakFrame weakFrame(this);
+
+  RefPtr<nsPresContext> presContext = PresContext();
+  nsCOMPtr<nsIPresShell> presShell = presContext->GetPresShell();
+  nsCOMPtr<nsIContent> content = mContent;
+
+  if (verticalOverflowChanged) {
+    InternalScrollPortEvent event(true,
+      mVerticalOverflow ? eScrollPortOverflow : eScrollPortUnderflow,
+      nullptr);
+    event.mOrient = InternalScrollPortEvent::eVertical;
+    EventDispatcher::Dispatch(content, presContext, &event);
+  }
+
+  if (horizontalOverflowChanged) {
+    InternalScrollPortEvent event(true,
+      mHorizontalOverflow ? eScrollPortOverflow : eScrollPortUnderflow,
+      nullptr);
+    event.mOrient = InternalScrollPortEvent::eHorizontal;
+    EventDispatcher::Dispatch(content, presContext, &event);
+  }
+
+  // The synchronous event dispatch above can trigger reflow notifications.
+  // Flush those explicitly now, so that we can guard against potential infinite
+  // recursion. See bug 905909.
+  if (!weakFrame.IsAlive()) {
+    return;
+  }
+  NS_ASSERTION(!mCheckingOverflow, "mCheckingOverflow should not already be set");
+  // Don't use AutoRestore since we want to not touch mCheckingOverflow if we fail
+  // the weakFrame.IsAlive() check below
+  mCheckingOverflow = true;
+  presShell->FlushPendingNotifications(Flush_Layout);
+  if (!weakFrame.IsAlive()) {
+    return;
+  }
+  mCheckingOverflow = false;
+}
+
+void
+nsTreeBodyFrame::InvalidateScrollbars(const ScrollParts& aParts, nsWeakFrame& aWeakColumnsFrame)
+{
+  if (mUpdateBatchNest || !mView)
+    return;
+  nsWeakFrame weakFrame(this);
+
+  if (aParts.mVScrollbar) {
+    // Do Vertical Scrollbar 
+    nsAutoString maxposStr;
+
+    nscoord rowHeightAsPixels = nsPresContext::AppUnitsToIntCSSPixels(mRowHeight);
+
+    int32_t size = rowHeightAsPixels * (mRowCount > mPageLength ? mRowCount - mPageLength : 0);
+    maxposStr.AppendInt(size);
+    aParts.mVScrollbarContent->
+      SetAttr(kNameSpaceID_None, nsGkAtoms::maxpos, maxposStr, true);
+    ENSURE_TRUE(weakFrame.IsAlive());
+
+    // Also set our page increment and decrement.
+    nscoord pageincrement = mPageLength*rowHeightAsPixels;
+    nsAutoString pageStr;
+    pageStr.AppendInt(pageincrement);
+    aParts.mVScrollbarContent->
+      SetAttr(kNameSpaceID_None, nsGkAtoms::pageincrement, pageStr, true);
+    ENSURE_TRUE(weakFrame.IsAlive());
+  }
+
+  if (aParts.mHScrollbar && aParts.mColumnsFrame && aWeakColumnsFrame.IsAlive()) {
+    // And now Horizontal scrollbar
+    nsRect bounds = aParts.mColumnsFrame->GetRect();
+    nsAutoString maxposStr;
+
+    maxposStr.AppendInt(mHorzWidth > bounds.width ? mHorzWidth - bounds.width : 0);
+    aParts.mHScrollbarContent->
+      SetAttr(kNameSpaceID_None, nsGkAtoms::maxpos, maxposStr, true);
+    ENSURE_TRUE(weakFrame.IsAlive());
+  
+    nsAutoString pageStr;
+    pageStr.AppendInt(bounds.width);
+    aParts.mHScrollbarContent->
+      SetAttr(kNameSpaceID_None, nsGkAtoms::pageincrement, pageStr, true);
+    ENSURE_TRUE(weakFrame.IsAlive());
+  
+    pageStr.Truncate();
+    pageStr.AppendInt(nsPresContext::CSSPixelsToAppUnits(16));
+    aParts.mHScrollbarContent->
+      SetAttr(kNameSpaceID_None, nsGkAtoms::increment, pageStr, true);
+  }
+
+  if (weakFrame.IsAlive() && mScrollbarActivity) {
+    mScrollbarActivity->ActivityOccurred();
+  }
+}
+
+// Takes client x/y in pixels, converts them to appunits, and converts into
+// values relative to this nsTreeBodyFrame frame.
+nsPoint
+nsTreeBodyFrame::AdjustClientCoordsToBoxCoordSpace(int32_t aX, int32_t aY)
+{
+  nsPoint point(nsPresContext::CSSPixelsToAppUnits(aX),
+                nsPresContext::CSSPixelsToAppUnits(aY));
+
+  nsPresContext* presContext = PresContext();
+  point -= GetOffsetTo(presContext->GetPresShell()->GetRootFrame());
+
+  // Adjust by the inner box coords, so that we're in the inner box's
+  // coordinate space.
+  point -= mInnerBox.TopLeft();
+  return point;
+} // AdjustClientCoordsToBoxCoordSpace
+
+nsresult
+nsTreeBodyFrame::GetRowAt(int32_t aX, int32_t aY, int32_t* _retval)
+{
+  if (!mView)
+    return NS_OK;
+
+  nsPoint point = AdjustClientCoordsToBoxCoordSpace(aX, aY);
+
+  // Check if the coordinates are above our visible space.
+  if (point.y < 0) {
+    *_retval = -1;
+    return NS_OK;
+  }
+
+  *_retval = GetRowAt(point.x, point.y);
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::GetCellAt(int32_t aX, int32_t aY, int32_t* aRow, nsITreeColumn** aCol,
+                           nsACString& aChildElt)
+{
+  if (!mView)
+    return NS_OK;
+
+  nsPoint point = AdjustClientCoordsToBoxCoordSpace(aX, aY);
+
+  // Check if the coordinates are above our visible space.
+  if (point.y < 0) {
+    *aRow = -1;
+    return NS_OK;
+  }
+
+  nsTreeColumn* col;
+  nsIAtom* child;
+  GetCellAt(point.x, point.y, aRow, &col, &child);
+
+  if (col) {
+    NS_ADDREF(*aCol = col);
+    if (child == nsCSSAnonBoxes::moztreecell)
+      aChildElt.AssignLiteral("cell");
+    else if (child == nsCSSAnonBoxes::moztreetwisty)
+      aChildElt.AssignLiteral("twisty");
+    else if (child == nsCSSAnonBoxes::moztreeimage)
+      aChildElt.AssignLiteral("image");
+    else if (child == nsCSSAnonBoxes::moztreecelltext)
+      aChildElt.AssignLiteral("text");
+  }
+
+  return NS_OK;
+}
+
+
+//
+// GetCoordsForCellItem
+//
+// Find the x/y location and width/height (all in PIXELS) of the given object
+// in the given column. 
+//
+// XXX IMPORTANT XXX:
+// Hyatt says in the bug for this, that the following needs to be done:
+// (1) You need to deal with overflow when computing cell rects.  See other column 
+// iteration examples... if you don't deal with this, you'll mistakenly extend the 
+// cell into the scrollbar's rect.
+//
+// (2) You are adjusting the cell rect by the *row" border padding.  That's 
+// wrong.  You need to first adjust a row rect by its border/padding, and then the 
+// cell rect fits inside the adjusted row rect.  It also can have border/padding 
+// as well as margins.  The vertical direction isn't that important, but you need 
+// to get the horizontal direction right.
+//
+// (3) GetImageSize() does not include margins (but it does include border/padding).  
+// You need to make sure to add in the image's margins as well.
+//
+nsresult
+nsTreeBodyFrame::GetCoordsForCellItem(int32_t aRow, nsITreeColumn* aCol, const nsACString& aElement, 
+                                      int32_t *aX, int32_t *aY, int32_t *aWidth, int32_t *aHeight)
+{
+  *aX = 0;
+  *aY = 0;
+  *aWidth = 0;
+  *aHeight = 0;
+
+  bool isRTL = StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
+  nscoord currX = mInnerBox.x - mHorzPosition;
+
+  // The Rect for the requested item. 
+  nsRect theRect;
+
+  nsPresContext* presContext = PresContext();
+
+  for (nsTreeColumn* currCol = mColumns->GetFirstColumn(); currCol; currCol = currCol->GetNext()) {
+
+    // The Rect for the current cell.
+    nscoord colWidth;
+#ifdef DEBUG
+    nsresult rv =
+#endif
+      currCol->GetWidthInTwips(this, &colWidth);
+    NS_ASSERTION(NS_SUCCEEDED(rv), "invalid column");
+
+    nsRect cellRect(currX, mInnerBox.y + mRowHeight * (aRow - mTopRowIndex),
+                    colWidth, mRowHeight);
+
+    // Check the ID of the current column to see if it matches. If it doesn't 
+    // increment the current X value and continue to the next column.
+    if (currCol != aCol) {
+      currX += cellRect.width;
+      continue;
+    }
+    // Now obtain the properties for our cell.
+    PrefillPropertyArray(aRow, currCol);
+
+    nsAutoString properties;
+    mView->GetCellProperties(aRow, currCol, properties);
+    nsTreeUtils::TokenizeProperties(properties, mScratchArray);
+
+    nsStyleContext* rowContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreerow);
+
+    // We don't want to consider any of the decorations that may be present
+    // on the current row, so we have to deflate the rect by the border and 
+    // padding and offset its left and top coordinates appropriately. 
+    AdjustForBorderPadding(rowContext, cellRect);
+
+    nsStyleContext* cellContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecell);
+
+    NS_NAMED_LITERAL_CSTRING(cell, "cell");
+    if (currCol->IsCycler() || cell.Equals(aElement)) {
+      // If the current Column is a Cycler, then the Rect is just the cell - the margins. 
+      // Similarly, if we're just being asked for the cell rect, provide it. 
+
+      theRect = cellRect;
+      nsMargin cellMargin;
+      cellContext->StyleMargin()->GetMargin(cellMargin);
+      theRect.Deflate(cellMargin);
+      break;
+    }
+
+    // Since we're not looking for the cell, and since the cell isn't a cycler,
+    // we're looking for some subcomponent, and now we need to subtract the 
+    // borders and padding of the cell from cellRect so this does not 
+    // interfere with our computations.
+    AdjustForBorderPadding(cellContext, cellRect);
+
+    nsRenderingContext rc(
+      presContext->PresShell()->CreateReferenceRenderingContext());
+
+    // Now we'll start making our way across the cell, starting at the edge of 
+    // the cell and proceeding until we hit the right edge. |cellX| is the 
+    // working X value that we will increment as we crawl from left to right.
+    nscoord cellX = cellRect.x;
+    nscoord remainWidth = cellRect.width;
+
+    if (currCol->IsPrimary()) {
+      // If the current Column is a Primary, then we need to take into account the indentation
+      // and possibly a twisty. 
+
+      // The amount of indentation is the indentation width (|mIndentation|) by the level. 
+      int32_t level;
+      mView->GetLevel(aRow, &level);
+      if (!isRTL)
+        cellX += mIndentation * level;
+      remainWidth -= mIndentation * level;
+
+      // Find the twisty rect by computing its size. 
+      nsRect imageRect;
+      nsRect twistyRect(cellRect);
+      nsStyleContext* twistyContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreetwisty);
+      GetTwistyRect(aRow, currCol, imageRect, twistyRect, presContext,
+                    twistyContext);
+
+      if (NS_LITERAL_CSTRING("twisty").Equals(aElement)) {
+        // If we're looking for the twisty Rect, just return the size
+        theRect = twistyRect;
+        break;
+      }
+      
+      // Now we need to add in the margins of the twisty element, so that we 
+      // can find the offset of the next element in the cell. 
+      nsMargin twistyMargin;
+      twistyContext->StyleMargin()->GetMargin(twistyMargin);
+      twistyRect.Inflate(twistyMargin);
+
+      // Adjust our working X value with the twisty width (image size, margins,
+      // borders, padding.
+      if (!isRTL)
+        cellX += twistyRect.width;
+    }
+
+    // Cell Image
+    nsStyleContext* imageContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreeimage);
+
+    nsRect imageSize = GetImageSize(aRow, currCol, false, imageContext);
+    if (NS_LITERAL_CSTRING("image").Equals(aElement)) {
+      theRect = imageSize;
+      theRect.x = cellX;
+      theRect.y = cellRect.y;
+      break;
+    }
+
+    // Add in the margins of the cell image.
+    nsMargin imageMargin;
+    imageContext->StyleMargin()->GetMargin(imageMargin);
+    imageSize.Inflate(imageMargin);
+
+    // Increment cellX by the image width
+    if (!isRTL)
+      cellX += imageSize.width;
+    
+    // Cell Text 
+    nsAutoString cellText;
+    mView->GetCellText(aRow, currCol, cellText);
+    // We're going to measure this text so we need to ensure bidi is enabled if
+    // necessary
+    CheckTextForBidi(cellText);
+
+    // Create a scratch rect to represent the text rectangle, with the current 
+    // X and Y coords, and a guess at the width and height. The width is the 
+    // remaining width we have left to traverse in the cell, which will be the
+    // widest possible value for the text rect, and the row height. 
+    nsRect textRect(cellX, cellRect.y, remainWidth, cellRect.height);
+
+    // Measure the width of the text. If the width of the text is greater than 
+    // the remaining width available, then we just assume that the text has 
+    // been cropped and use the remaining rect as the text Rect. Otherwise,
+    // we add in borders and padding to the text dimension and give that back. 
+    nsStyleContext* textContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecelltext);
+
+    RefPtr<nsFontMetrics> fm =
+      nsLayoutUtils::GetFontMetricsForStyleContext(textContext);
+    nscoord height = fm->MaxHeight();
+
+    nsMargin textMargin;
+    textContext->StyleMargin()->GetMargin(textMargin);
+    textRect.Deflate(textMargin);
+
+    // Center the text. XXX Obey vertical-align style prop?
+    if (height < textRect.height) {
+      textRect.y += (textRect.height - height) / 2;
+      textRect.height = height;
+    }
+
+    nsMargin bp(0,0,0,0);
+    GetBorderPadding(textContext, bp);
+    textRect.height += bp.top + bp.bottom;
+
+    AdjustForCellText(cellText, aRow, currCol, rc, *fm, textRect);
+
+    theRect = textRect;
+  }
+
+  if (isRTL)
+    theRect.x = mInnerBox.width - theRect.x - theRect.width;
+
+  *aX = nsPresContext::AppUnitsToIntCSSPixels(theRect.x);
+  *aY = nsPresContext::AppUnitsToIntCSSPixels(theRect.y);
+  *aWidth = nsPresContext::AppUnitsToIntCSSPixels(theRect.width);
+  *aHeight = nsPresContext::AppUnitsToIntCSSPixels(theRect.height);
+
+  return NS_OK;
+}
+
+int32_t
+nsTreeBodyFrame::GetRowAt(int32_t aX, int32_t aY)
+{
+  // Now just mod by our total inner box height and add to our top row index.
+  int32_t row = (aY/mRowHeight)+mTopRowIndex;
+
+  // Check if the coordinates are below our visible space (or within our visible
+  // space but below any row).
+  if (row > mTopRowIndex + mPageLength || row >= mRowCount)
+    return -1;
+
+  return row;
+}
+
+void
+nsTreeBodyFrame::CheckTextForBidi(nsAutoString& aText)
+{
+  // We could check to see whether the prescontext already has bidi enabled,
+  // but usually it won't, so it's probably faster to avoid the call to
+  // GetPresContext() when it's not needed.
+  if (HasRTLChars(aText)) {
+    PresContext()->SetBidiEnabled();
+  }
+}
+
+void
+nsTreeBodyFrame::AdjustForCellText(nsAutoString& aText,
+                                   int32_t aRowIndex,  nsTreeColumn* aColumn,
+                                   nsRenderingContext& aRenderingContext,
+                                   nsFontMetrics& aFontMetrics,
+                                   nsRect& aTextRect)
+{
+  NS_PRECONDITION(aColumn && aColumn->GetFrame(), "invalid column passed");
+
+  DrawTarget* drawTarget = aRenderingContext.GetDrawTarget();
+
+  nscoord maxWidth = aTextRect.width;
+  bool widthIsGreater = nsLayoutUtils::StringWidthIsGreaterThan(aText,
+                                                                aFontMetrics,
+                                                                drawTarget,
+                                                                maxWidth);
+
+  if (aColumn->Overflow()) {
+    DebugOnly<nsresult> rv;
+    nsTreeColumn* nextColumn = aColumn->GetNext();
+    while (nextColumn && widthIsGreater) {
+      while (nextColumn) {
+        nscoord width;
+        rv = nextColumn->GetWidthInTwips(this, &width);
+        NS_ASSERTION(NS_SUCCEEDED(rv), "nextColumn is invalid");
+
+        if (width != 0)
+          break;
+
+        nextColumn = nextColumn->GetNext();
+      }
+
+      if (nextColumn) {
+        nsAutoString nextText;
+        mView->GetCellText(aRowIndex, nextColumn, nextText);
+        // We don't measure or draw this text so no need to check it for
+        // bidi-ness
+
+        if (nextText.Length() == 0) {
+          nscoord width;
+          rv = nextColumn->GetWidthInTwips(this, &width);
+          NS_ASSERTION(NS_SUCCEEDED(rv), "nextColumn is invalid");
+
+          maxWidth += width;
+          widthIsGreater = nsLayoutUtils::StringWidthIsGreaterThan(aText,
+                                                                   aFontMetrics,
+                                                                   drawTarget,
+                                                                   maxWidth);
+
+          nextColumn = nextColumn->GetNext();
+        }
+        else {
+          nextColumn = nullptr;
+        }
+      }
+    }
+  }
+
+  nscoord width;
+  if (widthIsGreater) {
+    // See if the width is even smaller than the ellipsis
+    // If so, clear the text completely.
+    const nsDependentString& kEllipsis = nsContentUtils::GetLocalizedEllipsis();
+    aFontMetrics.SetTextRunRTL(false);
+    nscoord ellipsisWidth =
+      nsLayoutUtils::AppUnitWidthOfString(kEllipsis, aFontMetrics, drawTarget);
+
+    width = maxWidth;
+    if (ellipsisWidth > width)
+      aText.SetLength(0);
+    else if (ellipsisWidth == width)
+      aText.Assign(kEllipsis);
+    else {
+      // We will be drawing an ellipsis, thank you very much.
+      // Subtract out the required width of the ellipsis.
+      // This is the total remaining width we have to play with.
+      width -= ellipsisWidth;
+
+      // Now we crop.
+      switch (aColumn->GetCropStyle()) {
+        default:
+        case 0: {
+          // Crop right.
+          nscoord cwidth;
+          nscoord twidth = 0;
+          uint32_t length = aText.Length();
+          uint32_t i;
+          for (i = 0; i < length; ++i) {
+            char16_t ch = aText[i];
+            // XXX this is horrible and doesn't handle clusters
+            cwidth = nsLayoutUtils::AppUnitWidthOfString(ch, aFontMetrics,
+                                                         drawTarget);
+            if (twidth + cwidth > width)
+              break;
+            twidth += cwidth;
+          }
+          aText.Truncate(i);
+          aText.Append(kEllipsis);
+        }
+        break;
+
+        case 2: {
+          // Crop left.
+          nscoord cwidth;
+          nscoord twidth = 0;
+          int32_t length = aText.Length();
+          int32_t i;
+          for (i=length-1; i >= 0; --i) {
+            char16_t ch = aText[i];
+            cwidth = nsLayoutUtils::AppUnitWidthOfString(ch, aFontMetrics,
+                                                         drawTarget);
+            if (twidth + cwidth > width)
+              break;
+            twidth += cwidth;
+          }
+
+          nsAutoString copy;
+          aText.Right(copy, length-1-i);
+          aText.Assign(kEllipsis);
+          aText += copy;
+        }
+        break;
+
+        case 1:
+        {
+          // Crop center.
+          nsAutoString leftStr, rightStr;
+          nscoord cwidth, twidth = 0;
+          int32_t length = aText.Length();
+          int32_t rightPos = length - 1;
+          for (int32_t leftPos = 0; leftPos < rightPos; ++leftPos) {
+            char16_t ch = aText[leftPos];
+            cwidth = nsLayoutUtils::AppUnitWidthOfString(ch, aFontMetrics,
+                                                         drawTarget);
+            twidth += cwidth;
+            if (twidth > width)
+              break;
+            leftStr.Append(ch);
+
+            ch = aText[rightPos];
+            cwidth = nsLayoutUtils::AppUnitWidthOfString(ch, aFontMetrics,
+                                                         drawTarget);
+            twidth += cwidth;
+            if (twidth > width)
+              break;
+            rightStr.Insert(ch, 0);
+            --rightPos;
+          }
+          aText = leftStr;
+          aText.Append(kEllipsis);
+          aText += rightStr;
+        }
+        break;
+      }
+    }
+  }
+
+  width = nsLayoutUtils::AppUnitWidthOfStringBidi(aText, this, aFontMetrics,
+                                                  aRenderingContext);
+
+  switch (aColumn->GetTextAlignment()) {
+    case NS_STYLE_TEXT_ALIGN_RIGHT: {
+      aTextRect.x += aTextRect.width - width;
+    }
+    break;
+    case NS_STYLE_TEXT_ALIGN_CENTER: {
+      aTextRect.x += (aTextRect.width - width) / 2;
+    }
+    break;
+  }
+
+  aTextRect.width = width;
+}
+
+nsIAtom*
+nsTreeBodyFrame::GetItemWithinCellAt(nscoord aX, const nsRect& aCellRect, 
+                                     int32_t aRowIndex,
+                                     nsTreeColumn* aColumn)
+{
+  NS_PRECONDITION(aColumn && aColumn->GetFrame(), "invalid column passed");
+
+  // Obtain the properties for our cell.
+  PrefillPropertyArray(aRowIndex, aColumn);
+  nsAutoString properties;
+  mView->GetCellProperties(aRowIndex, aColumn, properties);
+  nsTreeUtils::TokenizeProperties(properties, mScratchArray);
+
+  // Resolve style for the cell.
+  nsStyleContext* cellContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecell);
+
+  // Obtain the margins for the cell and then deflate our rect by that 
+  // amount.  The cell is assumed to be contained within the deflated rect.
+  nsRect cellRect(aCellRect);
+  nsMargin cellMargin;
+  cellContext->StyleMargin()->GetMargin(cellMargin);
+  cellRect.Deflate(cellMargin);
+
+  // Adjust the rect for its border and padding.
+  AdjustForBorderPadding(cellContext, cellRect);
+
+  if (aX < cellRect.x || aX >= cellRect.x + cellRect.width) {
+    // The user clicked within the cell's margins/borders/padding.  This constitutes a click on the cell.
+    return nsCSSAnonBoxes::moztreecell;
+  }
+
+  nscoord currX = cellRect.x;
+  nscoord remainingWidth = cellRect.width;
+
+  // Handle right alignment hit testing.
+  bool isRTL = StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
+
+  nsPresContext* presContext = PresContext();
+  nsRenderingContext rc(
+    presContext->PresShell()->CreateReferenceRenderingContext());
+
+  if (aColumn->IsPrimary()) {
+    // If we're the primary column, we have indentation and a twisty.
+    int32_t level;
+    mView->GetLevel(aRowIndex, &level);
+
+    if (!isRTL)
+      currX += mIndentation*level;
+    remainingWidth -= mIndentation*level;
+
+    if ((isRTL && aX > currX + remainingWidth) ||
+        (!isRTL && aX < currX)) {
+      // The user clicked within the indentation.
+      return nsCSSAnonBoxes::moztreecell;
+    }
+
+    // Always leave space for the twisty.
+    nsRect twistyRect(currX, cellRect.y, remainingWidth, cellRect.height);
+    bool hasTwisty = false;
+    bool isContainer = false;
+    mView->IsContainer(aRowIndex, &isContainer);
+    if (isContainer) {
+      bool isContainerEmpty = false;
+      mView->IsContainerEmpty(aRowIndex, &isContainerEmpty);
+      if (!isContainerEmpty)
+        hasTwisty = true;
+    }
+
+    // Resolve style for the twisty.
+    nsStyleContext* twistyContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreetwisty);
+
+    nsRect imageSize;
+    GetTwistyRect(aRowIndex, aColumn, imageSize, twistyRect, presContext,
+                  twistyContext);
+
+    // We will treat a click as hitting the twisty if it happens on the margins, borders, padding,
+    // or content of the twisty object.  By allowing a "slop" into the margin, we make it a little
+    // bit easier for a user to hit the twisty.  (We don't want to be too picky here.)
+    nsMargin twistyMargin;
+    twistyContext->StyleMargin()->GetMargin(twistyMargin);
+    twistyRect.Inflate(twistyMargin);
+    if (isRTL)
+      twistyRect.x = currX + remainingWidth - twistyRect.width;
+
+    // Now we test to see if aX is actually within the twistyRect.  If it is, and if the item should
+    // have a twisty, then we return "twisty".  If it is within the rect but we shouldn't have a twisty,
+    // then we return "cell".
+    if (aX >= twistyRect.x && aX < twistyRect.x + twistyRect.width) {
+      if (hasTwisty)
+        return nsCSSAnonBoxes::moztreetwisty;
+      else
+        return nsCSSAnonBoxes::moztreecell;
+    }
+
+    if (!isRTL)
+      currX += twistyRect.width;
+    remainingWidth -= twistyRect.width;    
+  }
+  
+  // Now test to see if the user hit the icon for the cell.
+  nsRect iconRect(currX, cellRect.y, remainingWidth, cellRect.height);
+  
+  // Resolve style for the image.
+  nsStyleContext* imageContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreeimage);
+
+  nsRect iconSize = GetImageSize(aRowIndex, aColumn, false, imageContext);
+  nsMargin imageMargin;
+  imageContext->StyleMargin()->GetMargin(imageMargin);
+  iconSize.Inflate(imageMargin);
+  iconRect.width = iconSize.width;
+  if (isRTL)
+    iconRect.x = currX + remainingWidth - iconRect.width;
+
+  if (aX >= iconRect.x && aX < iconRect.x + iconRect.width) {
+    // The user clicked on the image.
+    return nsCSSAnonBoxes::moztreeimage;
+  }
+
+  if (!isRTL)
+    currX += iconRect.width;
+  remainingWidth -= iconRect.width;    
+
+  nsAutoString cellText;
+  mView->GetCellText(aRowIndex, aColumn, cellText);
+  // We're going to measure this text so we need to ensure bidi is enabled if
+  // necessary
+  CheckTextForBidi(cellText);
+
+  nsRect textRect(currX, cellRect.y, remainingWidth, cellRect.height);
+
+  nsStyleContext* textContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecelltext);
+
+  nsMargin textMargin;
+  textContext->StyleMargin()->GetMargin(textMargin);
+  textRect.Deflate(textMargin);
+
+  AdjustForBorderPadding(textContext, textRect);
+
+  RefPtr<nsFontMetrics> fm =
+    nsLayoutUtils::GetFontMetricsForStyleContext(textContext);
+  AdjustForCellText(cellText, aRowIndex, aColumn, rc, *fm, textRect);
+
+  if (aX >= textRect.x && aX < textRect.x + textRect.width)
+    return nsCSSAnonBoxes::moztreecelltext;
+  else
+    return nsCSSAnonBoxes::moztreecell;
+}
+
+void
+nsTreeBodyFrame::GetCellAt(nscoord aX, nscoord aY, int32_t* aRow,
+                           nsTreeColumn** aCol, nsIAtom** aChildElt)
+{
+  *aCol = nullptr;
+  *aChildElt = nullptr;
+
+  *aRow = GetRowAt(aX, aY);
+  if (*aRow < 0)
+    return;
+
+  // Determine the column hit.
+  for (nsTreeColumn* currCol = mColumns->GetFirstColumn(); currCol; 
+       currCol = currCol->GetNext()) {
+    nsRect cellRect;
+    nsresult rv = currCol->GetRect(this,
+                                   mInnerBox.y +
+                                         mRowHeight * (*aRow - mTopRowIndex),
+                                   mRowHeight,
+                                   &cellRect);
+    if (NS_FAILED(rv)) {
+      NS_NOTREACHED("column has no frame");
+      continue;
+    }
+
+    if (!OffsetForHorzScroll(cellRect, false))
+      continue;
+
+    if (aX >= cellRect.x && aX < cellRect.x + cellRect.width) {
+      // We know the column hit now.
+      *aCol = currCol;
+
+      if (currCol->IsCycler())
+        // Cyclers contain only images.  Fill this in immediately and return.
+        *aChildElt = nsCSSAnonBoxes::moztreeimage;
+      else
+        *aChildElt = GetItemWithinCellAt(aX, cellRect, *aRow, currCol);
+      break;
+    }
+  }
+}
+
+nsresult
+nsTreeBodyFrame::GetCellWidth(int32_t aRow, nsTreeColumn* aCol,
+                              nsRenderingContext* aRenderingContext,
+                              nscoord& aDesiredSize, nscoord& aCurrentSize)
+{
+  NS_PRECONDITION(aCol, "aCol must not be null");
+  NS_PRECONDITION(aRenderingContext, "aRenderingContext must not be null");
+
+  // The rect for the current cell.
+  nscoord colWidth;
+  nsresult rv = aCol->GetWidthInTwips(this, &colWidth);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsRect cellRect(0, 0, colWidth, mRowHeight);
+
+  int32_t overflow = cellRect.x+cellRect.width-(mInnerBox.x+mInnerBox.width);
+  if (overflow > 0)
+    cellRect.width -= overflow;
+
+  // Adjust borders and padding for the cell.
+  nsStyleContext* cellContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecell);
+  nsMargin bp(0,0,0,0);
+  GetBorderPadding(cellContext, bp);
+
+  aCurrentSize = cellRect.width;
+  aDesiredSize = bp.left + bp.right;
+
+  if (aCol->IsPrimary()) {
+    // If the current Column is a Primary, then we need to take into account 
+    // the indentation and possibly a twisty. 
+
+    // The amount of indentation is the indentation width (|mIndentation|) by the level.
+    int32_t level;
+    mView->GetLevel(aRow, &level);
+    aDesiredSize += mIndentation * level;
+    
+    // Find the twisty rect by computing its size.
+    nsStyleContext* twistyContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreetwisty);
+
+    nsRect imageSize;
+    nsRect twistyRect(cellRect);
+    GetTwistyRect(aRow, aCol, imageSize, twistyRect, PresContext(),
+                  twistyContext);
+
+    // Add in the margins of the twisty element.
+    nsMargin twistyMargin;
+    twistyContext->StyleMargin()->GetMargin(twistyMargin);
+    twistyRect.Inflate(twistyMargin);
+
+    aDesiredSize += twistyRect.width;
+  }
+
+  nsStyleContext* imageContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreeimage);
+
+  // Account for the width of the cell image.
+  nsRect imageSize = GetImageSize(aRow, aCol, false, imageContext);
+  // Add in the margins of the cell image.
+  nsMargin imageMargin;
+  imageContext->StyleMargin()->GetMargin(imageMargin);
+  imageSize.Inflate(imageMargin);
+
+  aDesiredSize += imageSize.width;
+  
+  // Get the cell text.
+  nsAutoString cellText;
+  mView->GetCellText(aRow, aCol, cellText);
+  // We're going to measure this text so we need to ensure bidi is enabled if
+  // necessary
+  CheckTextForBidi(cellText);
+
+  nsStyleContext* textContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecelltext);
+
+  // Get the borders and padding for the text.
+  GetBorderPadding(textContext, bp);
+
+  RefPtr<nsFontMetrics> fm =
+    nsLayoutUtils::GetFontMetricsForStyleContext(textContext);
+  // Get the width of the text itself
+  nscoord width = nsLayoutUtils::AppUnitWidthOfStringBidi(cellText, this, *fm,
+                                                          *aRenderingContext);
+  nscoord totalTextWidth = width + bp.left + bp.right;
+  aDesiredSize += totalTextWidth;
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::IsCellCropped(int32_t aRow, nsITreeColumn* aCol, bool *_retval)
+{  
+  nscoord currentSize, desiredSize;
+  nsresult rv;
+
+  RefPtr<nsTreeColumn> col = GetColumnImpl(aCol);
+  if (!col)
+    return NS_ERROR_INVALID_ARG;
+
+  nsRenderingContext rc(
+    PresContext()->PresShell()->CreateReferenceRenderingContext());
+
+  rv = GetCellWidth(aRow, col, &rc, desiredSize, currentSize);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  *_retval = desiredSize > currentSize;
+
+  return NS_OK;
+}
+
+void
+nsTreeBodyFrame::MarkDirtyIfSelect()
+{
+  nsIContent* baseElement = GetBaseElement();
+
+  if (baseElement && baseElement->IsHTMLElement(nsGkAtoms::select)) {
+    // If we are an intrinsically sized select widget, we may need to
+    // resize, if the widest item was removed or a new item was added.
+    // XXX optimize this more
+
+    mStringWidth = -1;
+    PresContext()->PresShell()->FrameNeedsReflow(this,
+                                                 nsIPresShell::eTreeChange,
+                                                 NS_FRAME_IS_DIRTY);
+  }
+}
+
+nsresult
+nsTreeBodyFrame::CreateTimer(const LookAndFeel::IntID aID,
+                             nsTimerCallbackFunc aFunc, int32_t aType,
+                             nsITimer** aTimer)
+{
+  // Get the delay from the look and feel service.
+  int32_t delay = LookAndFeel::GetInt(aID, 0);
+
+  nsCOMPtr<nsITimer> timer;
+
+  // Create a new timer only if the delay is greater than zero.
+  // Zero value means that this feature is completely disabled.
+  if (delay > 0) {
+    timer = do_CreateInstance("@mozilla.org/timer;1");
+    if (timer)
+      timer->InitWithFuncCallback(aFunc, this, delay, aType);
+  }
+
+  NS_IF_ADDREF(*aTimer = timer);
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::RowCountChanged(int32_t aIndex, int32_t aCount)
+{
+  if (aCount == 0 || !mView)
+    return NS_OK; // Nothing to do.
+
+#ifdef ACCESSIBILITY
+  if (nsIPresShell::IsAccessibilityActive())
+    FireRowCountChangedEvent(aIndex, aCount);
+#endif
+
+  // Adjust our selection.
+  nsCOMPtr<nsITreeSelection> sel;
+  mView->GetSelection(getter_AddRefs(sel));
+  if (sel)
+    sel->AdjustSelection(aIndex, aCount);
+
+  if (mUpdateBatchNest)
+    return NS_OK;
+
+  mRowCount += aCount;
+#ifdef DEBUG
+  int32_t rowCount = mRowCount;
+  mView->GetRowCount(&rowCount);
+  NS_ASSERTION(rowCount == mRowCount, "row count did not change by the amount suggested, check caller");
+#endif
+
+  int32_t count = Abs(aCount);
+  int32_t last = LastVisibleRow();
+  if (aIndex >= mTopRowIndex && aIndex <= last)
+    InvalidateRange(aIndex, last);
+    
+  ScrollParts parts = GetScrollParts();
+
+  if (mTopRowIndex == 0) {    
+    // Just update the scrollbar and return.
+    if (FullScrollbarsUpdate(false)) {
+      MarkDirtyIfSelect();
+    }
+    return NS_OK;
+  }
+
+  bool needsInvalidation = false;
+  // Adjust our top row index.
+  if (aCount > 0) {
+    if (mTopRowIndex > aIndex) {
+      // Rows came in above us.  Augment the top row index.
+      mTopRowIndex += aCount;
+    }
+  }
+  else if (aCount < 0) {
+    if (mTopRowIndex > aIndex+count-1) {
+      // No need to invalidate. The remove happened
+      // completely above us (offscreen).
+      mTopRowIndex -= count;
+    }
+    else if (mTopRowIndex >= aIndex) {
+      // This is a full-blown invalidate.
+      if (mTopRowIndex + mPageLength > mRowCount - 1) {
+        mTopRowIndex = std::max(0, mRowCount - 1 - mPageLength);
+      }
+      needsInvalidation = true;
+    }
+  }
+
+  if (FullScrollbarsUpdate(needsInvalidation)) {
+    MarkDirtyIfSelect();
+  }
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::BeginUpdateBatch()
+{
+  ++mUpdateBatchNest;
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::EndUpdateBatch()
+{
+  NS_ASSERTION(mUpdateBatchNest > 0, "badly nested update batch");
+
+  if (--mUpdateBatchNest == 0) {
+    if (mView) {
+      Invalidate();
+      int32_t countBeforeUpdate = mRowCount;
+      mView->GetRowCount(&mRowCount);
+      if (countBeforeUpdate != mRowCount) {
+        if (mTopRowIndex + mPageLength > mRowCount - 1) {
+          mTopRowIndex = std::max(0, mRowCount - 1 - mPageLength);
+        }
+        FullScrollbarsUpdate(false);
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+void
+nsTreeBodyFrame::PrefillPropertyArray(int32_t aRowIndex, nsTreeColumn* aCol)
+{
+  NS_PRECONDITION(!aCol || aCol->GetFrame(), "invalid column passed");
+  mScratchArray.Clear();
+  
+  // focus
+  if (mFocused)
+    mScratchArray.AppendElement(nsGkAtoms::focus);
+
+  // sort
+  bool sorted = false;
+  mView->IsSorted(&sorted);
+  if (sorted)
+    mScratchArray.AppendElement(nsGkAtoms::sorted);
+
+  // drag session
+  if (mSlots && mSlots->mIsDragging)
+    mScratchArray.AppendElement(nsGkAtoms::dragSession);
+
+  if (aRowIndex != -1) {
+    if (aRowIndex == mMouseOverRow)
+      mScratchArray.AppendElement(nsGkAtoms::hover);
+  
+    nsCOMPtr<nsITreeSelection> selection;
+    mView->GetSelection(getter_AddRefs(selection));
+
+    if (selection) {
+      // selected
+      bool isSelected;
+      selection->IsSelected(aRowIndex, &isSelected);
+      if (isSelected)
+        mScratchArray.AppendElement(nsGkAtoms::selected);
+
+      // current
+      int32_t currentIndex;
+      selection->GetCurrentIndex(&currentIndex);
+      if (aRowIndex == currentIndex)
+        mScratchArray.AppendElement(nsGkAtoms::current);
+  
+      // active
+      if (aCol) {
+        nsCOMPtr<nsITreeColumn> currentColumn;
+        selection->GetCurrentColumn(getter_AddRefs(currentColumn));
+        if (aCol == currentColumn)
+          mScratchArray.AppendElement(nsGkAtoms::active);
+      }
+    }
+
+    // container or leaf
+    bool isContainer = false;
+    mView->IsContainer(aRowIndex, &isContainer);
+    if (isContainer) {
+      mScratchArray.AppendElement(nsGkAtoms::container);
+
+      // open or closed
+      bool isOpen = false;
+      mView->IsContainerOpen(aRowIndex, &isOpen);
+      if (isOpen)
+        mScratchArray.AppendElement(nsGkAtoms::open);
+      else
+        mScratchArray.AppendElement(nsGkAtoms::closed);
+    }
+    else {
+      mScratchArray.AppendElement(nsGkAtoms::leaf);
+    }
+
+    // drop orientation
+    if (mSlots && mSlots->mDropAllowed && mSlots->mDropRow == aRowIndex) {
+      if (mSlots->mDropOrient == nsITreeView::DROP_BEFORE)
+        mScratchArray.AppendElement(nsGkAtoms::dropBefore);
+      else if (mSlots->mDropOrient == nsITreeView::DROP_ON)
+        mScratchArray.AppendElement(nsGkAtoms::dropOn);
+      else if (mSlots->mDropOrient == nsITreeView::DROP_AFTER)
+        mScratchArray.AppendElement(nsGkAtoms::dropAfter);
+    }
+
+    // odd or even
+    if (aRowIndex % 2)
+      mScratchArray.AppendElement(nsGkAtoms::odd);
+    else
+      mScratchArray.AppendElement(nsGkAtoms::even);
+
+    nsIContent* baseContent = GetBaseElement();
+    if (baseContent && baseContent->HasAttr(kNameSpaceID_None, nsGkAtoms::editing))
+      mScratchArray.AppendElement(nsGkAtoms::editing);
+
+    // multiple columns
+    if (mColumns->GetColumnAt(1))
+      mScratchArray.AppendElement(nsGkAtoms::multicol);
+  }
+
+  if (aCol) {
+    mScratchArray.AppendElement(aCol->GetAtom());
+
+    if (aCol->IsPrimary())
+      mScratchArray.AppendElement(nsGkAtoms::primary);
+
+    if (aCol->GetType() == nsITreeColumn::TYPE_CHECKBOX) {
+      mScratchArray.AppendElement(nsGkAtoms::checkbox);
+
+      if (aRowIndex != -1) {
+        nsAutoString value;
+        mView->GetCellValue(aRowIndex, aCol, value);
+        if (value.EqualsLiteral("true"))
+          mScratchArray.AppendElement(nsGkAtoms::checked);
+      }
+    }
+    else if (aCol->GetType() == nsITreeColumn::TYPE_PROGRESSMETER) {
+      mScratchArray.AppendElement(nsGkAtoms::progressmeter);
+
+      if (aRowIndex != -1) {
+        int32_t state;
+        mView->GetProgressMode(aRowIndex, aCol, &state);
+        if (state == nsITreeView::PROGRESS_NORMAL)
+          mScratchArray.AppendElement(nsGkAtoms::progressNormal);
+        else if (state == nsITreeView::PROGRESS_UNDETERMINED)
+          mScratchArray.AppendElement(nsGkAtoms::progressUndetermined);
+      }
+    }
+
+    // Read special properties from attributes on the column content node
+    if (aCol->mContent->AttrValueIs(kNameSpaceID_None,
+                                    nsGkAtoms::insertbefore,
+                                    nsGkAtoms::_true, eCaseMatters))
+      mScratchArray.AppendElement(nsGkAtoms::insertbefore);
+    if (aCol->mContent->AttrValueIs(kNameSpaceID_None,
+                                    nsGkAtoms::insertafter,
+                                    nsGkAtoms::_true, eCaseMatters))
+      mScratchArray.AppendElement(nsGkAtoms::insertafter);
+  }
+}
+
+nsITheme*
+nsTreeBodyFrame::GetTwistyRect(int32_t aRowIndex,
+                               nsTreeColumn* aColumn,
+                               nsRect& aImageRect,
+                               nsRect& aTwistyRect,
+                               nsPresContext* aPresContext,
+                               nsStyleContext* aTwistyContext)
+{
+  // The twisty rect extends all the way to the end of the cell.  This is incorrect.  We need to
+  // determine the twisty rect's true width.  This is done by examining the style context for
+  // a width first.  If it has one, we use that.  If it doesn't, we use the image's natural width.
+  // If the image hasn't loaded and if no width is specified, then we just bail. If there is
+  // a -moz-appearance involved, adjust the rect by the minimum widget size provided by
+  // the theme implementation.
+  aImageRect = GetImageSize(aRowIndex, aColumn, true, aTwistyContext);
+  if (aImageRect.height > aTwistyRect.height)
+    aImageRect.height = aTwistyRect.height;
+  if (aImageRect.width > aTwistyRect.width)
+    aImageRect.width = aTwistyRect.width;
+  else
+    aTwistyRect.width = aImageRect.width;
+
+  bool useTheme = false;
+  nsITheme *theme = nullptr;
+  const nsStyleDisplay* twistyDisplayData = aTwistyContext->StyleDisplay();
+  if (twistyDisplayData->mAppearance) {
+    theme = aPresContext->GetTheme();
+    if (theme && theme->ThemeSupportsWidget(aPresContext, nullptr, twistyDisplayData->mAppearance))
+      useTheme = true;
+  }
+
+  if (useTheme) {
+    LayoutDeviceIntSize minTwistySizePx;
+    bool canOverride = true;
+    theme->GetMinimumWidgetSize(aPresContext, this, twistyDisplayData->mAppearance,
+                                &minTwistySizePx, &canOverride);
+
+    // GMWS() returns size in pixels, we need to convert it back to app units
+    nsSize minTwistySize;
+    minTwistySize.width = aPresContext->DevPixelsToAppUnits(minTwistySizePx.width);
+    minTwistySize.height = aPresContext->DevPixelsToAppUnits(minTwistySizePx.height);
+
+    if (aTwistyRect.width < minTwistySize.width || !canOverride)
+      aTwistyRect.width = minTwistySize.width;
+  }
+
+  return useTheme ? theme : nullptr;
+}
+
+nsresult
+nsTreeBodyFrame::GetImage(int32_t aRowIndex, nsTreeColumn* aCol, bool aUseContext,
+                          nsStyleContext* aStyleContext, bool& aAllowImageRegions, imgIContainer** aResult)
+{
+  *aResult = nullptr;
+
+  nsAutoString imageSrc;
+  mView->GetImageSrc(aRowIndex, aCol, imageSrc);
+  RefPtr<imgRequestProxy> styleRequest;
+  if (!aUseContext && !imageSrc.IsEmpty()) {
+    aAllowImageRegions = false;
+  }
+  else {
+    // Obtain the URL from the style context.
+    aAllowImageRegions = true;
+    styleRequest = aStyleContext->StyleList()->GetListStyleImage();
+    if (!styleRequest)
+      return NS_OK;
+    nsCOMPtr<nsIURI> uri;
+    styleRequest->GetURI(getter_AddRefs(uri));
+    nsAutoCString spec;
+    nsresult rv = uri->GetSpec(spec);
+    NS_ENSURE_SUCCESS(rv, rv);
+    CopyUTF8toUTF16(spec, imageSrc);
+  }
+
+  // Look the image up in our cache.
+  nsTreeImageCacheEntry entry;
+  if (mImageCache.Get(imageSrc, &entry)) {
+    // Find out if the image has loaded.
+    uint32_t status;
+    imgIRequest *imgReq = entry.request;
+    imgReq->GetImageStatus(&status);
+    imgReq->GetImage(aResult); // We hand back the image here.  The GetImage call addrefs *aResult.
+    bool animated = true; // Assuming animated is the safe option
+
+    // We can only call GetAnimated if we're decoded
+    if (*aResult && (status & imgIRequest::STATUS_DECODE_COMPLETE))
+      (*aResult)->GetAnimated(&animated);
+
+    if ((!(status & imgIRequest::STATUS_LOAD_COMPLETE)) || animated) {
+      // We either aren't done loading, or we're animating. Add our row as a listener for invalidations.
+      nsCOMPtr<imgINotificationObserver> obs;
+      imgReq->GetNotificationObserver(getter_AddRefs(obs));
+
+      if (obs) {
+        static_cast<nsTreeImageListener*> (obs.get())->AddCell(aRowIndex, aCol);
+      }
+
+      return NS_OK;
+    }
+  }
+
+  if (!*aResult) {
+    // Create a new nsTreeImageListener object and pass it our row and column
+    // information.
+    nsTreeImageListener* listener = new nsTreeImageListener(this);
+    if (!listener)
+      return NS_ERROR_OUT_OF_MEMORY;
+
+    if (!mCreatedListeners.PutEntry(listener)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    listener->AddCell(aRowIndex, aCol);
+    nsCOMPtr<imgINotificationObserver> imgNotificationObserver = listener;
+
+    RefPtr<imgRequestProxy> imageRequest;
+    if (styleRequest) {
+      styleRequest->Clone(imgNotificationObserver, getter_AddRefs(imageRequest));
+    } else {
+      nsIDocument* doc = mContent->GetComposedDoc();
+      if (!doc)
+        // The page is currently being torn down.  Why bother.
+        return NS_ERROR_FAILURE;
+
+      nsCOMPtr<nsIURI> baseURI = mContent->GetBaseURI();
+
+      nsCOMPtr<nsIURI> srcURI;
+      nsContentUtils::NewURIWithDocumentCharset(getter_AddRefs(srcURI),
+                                                imageSrc,
+                                                doc,
+                                                baseURI);
+      if (!srcURI)
+        return NS_ERROR_FAILURE;
+
+      // XXXbz what's the origin principal for this stuff that comes from our
+      // view?  I guess we should assume that it's the node's principal...
+      nsresult rv = nsContentUtils::LoadImage(srcURI,
+                                              mContent,
+                                              doc,
+                                              mContent->NodePrincipal(),
+                                              doc->GetDocumentURI(),
+                                              doc->GetReferrerPolicy(),
+                                              imgNotificationObserver,
+                                              nsIRequest::LOAD_NORMAL,
+                                              EmptyString(),
+                                              getter_AddRefs(imageRequest));
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+    listener->UnsuppressInvalidation();
+
+    if (!imageRequest)
+      return NS_ERROR_FAILURE;
+
+    // We don't want discarding/decode-on-draw for xul images
+    imageRequest->StartDecoding();
+    imageRequest->LockImage();
+
+    // In a case it was already cached.
+    imageRequest->GetImage(aResult);
+    nsTreeImageCacheEntry cacheEntry(imageRequest, imgNotificationObserver);
+    mImageCache.Put(imageSrc, cacheEntry);
+  }
+  return NS_OK;
+}
+
+nsRect nsTreeBodyFrame::GetImageSize(int32_t aRowIndex, nsTreeColumn* aCol, bool aUseContext,
+                                     nsStyleContext* aStyleContext)
+{
+  // XXX We should respond to visibility rules for collapsed vs. hidden.
+
+  // This method returns the width of the twisty INCLUDING borders and padding.
+  // It first checks the style context for a width.  If none is found, it tries to
+  // use the default image width for the twisty.  If no image is found, it defaults
+  // to border+padding.
+  nsRect r(0,0,0,0);
+  nsMargin bp(0,0,0,0);
+  GetBorderPadding(aStyleContext, bp);
+  r.Inflate(bp);
+
+  // Now r contains our border+padding info.  We now need to get our width and
+  // height.
+  bool needWidth = false;
+  bool needHeight = false;
+
+  // We have to load image even though we already have a size.
+  // Don't change this, otherwise things start to go crazy.
+  bool useImageRegion = true;
+  nsCOMPtr<imgIContainer> image;
+  GetImage(aRowIndex, aCol, aUseContext, aStyleContext, useImageRegion, getter_AddRefs(image));
+
+  const nsStylePosition* myPosition = aStyleContext->StylePosition();
+  const nsStyleList* myList = aStyleContext->StyleList();
+
+  if (useImageRegion) {
+    r.x += myList->mImageRegion.x;
+    r.y += myList->mImageRegion.y;
+  }
+
+  if (myPosition->mWidth.GetUnit() == eStyleUnit_Coord)  {
+    int32_t val = myPosition->mWidth.GetCoordValue();
+    r.width += val;
+  }
+  else if (useImageRegion && myList->mImageRegion.width > 0)
+    r.width += myList->mImageRegion.width;
+  else 
+    needWidth = true;
+
+  if (myPosition->mHeight.GetUnit() == eStyleUnit_Coord)  {
+    int32_t val = myPosition->mHeight.GetCoordValue();
+    r.height += val;
+  }
+  else if (useImageRegion && myList->mImageRegion.height > 0)
+    r.height += myList->mImageRegion.height;
+  else 
+    needHeight = true;
+
+  if (image) {
+    if (needWidth || needHeight) {
+      // Get the natural image size.
+
+      if (needWidth) {
+        // Get the size from the image.
+        nscoord width;
+        image->GetWidth(&width);
+        r.width += nsPresContext::CSSPixelsToAppUnits(width); 
+      }
+    
+      if (needHeight) {
+        nscoord height;
+        image->GetHeight(&height);
+        r.height += nsPresContext::CSSPixelsToAppUnits(height); 
+      }
+    }
+  }
+
+  return r;
+}
+
+// GetImageDestSize returns the destination size of the image.
+// The width and height do not include borders and padding.
+// The width and height have not been adjusted to fit in the row height
+// or cell width.
+// The width and height reflect the destination size specified in CSS,
+// or the image region specified in CSS, or the natural size of the
+// image.
+// If only the destination width has been specified in CSS, the height is
+// calculated to maintain the aspect ratio of the image.
+// If only the destination height has been specified in CSS, the width is
+// calculated to maintain the aspect ratio of the image.
+nsSize
+nsTreeBodyFrame::GetImageDestSize(nsStyleContext* aStyleContext,
+                                  bool useImageRegion,
+                                  imgIContainer* image)
+{
+  nsSize size(0,0);
+
+  // We need to get the width and height.
+  bool needWidth = false;
+  bool needHeight = false;
+
+  // Get the style position to see if the CSS has specified the
+  // destination width/height.
+  const nsStylePosition* myPosition = aStyleContext->StylePosition();
+
+  if (myPosition->mWidth.GetUnit() == eStyleUnit_Coord) {
+    // CSS has specified the destination width.
+    size.width = myPosition->mWidth.GetCoordValue();
+  }
+  else {
+    // We'll need to get the width of the image/region.
+    needWidth = true;
+  }
+
+  if (myPosition->mHeight.GetUnit() == eStyleUnit_Coord)  {
+    // CSS has specified the destination height.
+    size.height = myPosition->mHeight.GetCoordValue();
+  }
+  else {
+    // We'll need to get the height of the image/region.
+    needHeight = true;
+  }
+
+  if (needWidth || needHeight) {
+    // We need to get the size of the image/region.
+    nsSize imageSize(0,0);
+
+    const nsStyleList* myList = aStyleContext->StyleList();
+
+    if (useImageRegion && myList->mImageRegion.width > 0) {
+      // CSS has specified an image region.
+      // Use the width of the image region.
+      imageSize.width = myList->mImageRegion.width;
+    }
+    else if (image) {
+      nscoord width;
+      image->GetWidth(&width);
+      imageSize.width = nsPresContext::CSSPixelsToAppUnits(width);
+    }
+
+    if (useImageRegion && myList->mImageRegion.height > 0) {
+      // CSS has specified an image region.
+      // Use the height of the image region.
+      imageSize.height = myList->mImageRegion.height;
+    }
+    else if (image) {
+      nscoord height;
+      image->GetHeight(&height);
+      imageSize.height = nsPresContext::CSSPixelsToAppUnits(height);
+    }
+
+    if (needWidth) {
+      if (!needHeight && imageSize.height != 0) {
+        // The CSS specified the destination height, but not the destination
+        // width. We need to calculate the width so that we maintain the
+        // image's aspect ratio.
+        size.width = imageSize.width * size.height / imageSize.height;
+      }
+      else {
+        size.width = imageSize.width;
+      }
+    }
+
+    if (needHeight) {
+      if (!needWidth && imageSize.width != 0) {
+        // The CSS specified the destination width, but not the destination
+        // height. We need to calculate the height so that we maintain the
+        // image's aspect ratio.
+        size.height = imageSize.height * size.width / imageSize.width;
+      }
+      else {
+        size.height = imageSize.height;
+      }
+    }
+  }
+
+  return size;
+}
+
+// GetImageSourceRect returns the source rectangle of the image to be
+// displayed.
+// The width and height reflect the image region specified in CSS, or
+// the natural size of the image.
+// The width and height do not include borders and padding.
+// The width and height do not reflect the destination size specified
+// in CSS.
+nsRect
+nsTreeBodyFrame::GetImageSourceRect(nsStyleContext* aStyleContext,
+                                    bool useImageRegion,
+                                    imgIContainer* image)
+{
+  nsRect r(0,0,0,0);
+
+  const nsStyleList* myList = aStyleContext->StyleList();
+
+  if (useImageRegion &&
+      (myList->mImageRegion.width > 0 || myList->mImageRegion.height > 0)) {
+    // CSS has specified an image region.
+    r = myList->mImageRegion;
+  }
+  else if (image) {
+    // Use the actual image size.
+    nscoord coord;
+    image->GetWidth(&coord);
+    r.width = nsPresContext::CSSPixelsToAppUnits(coord);
+    image->GetHeight(&coord);
+    r.height = nsPresContext::CSSPixelsToAppUnits(coord);
+  }
+
+  return r;
+}
+
+int32_t nsTreeBodyFrame::GetRowHeight()
+{
+  // Look up the correct height.  It is equal to the specified height
+  // + the specified margins.
+  mScratchArray.Clear();
+  nsStyleContext* rowContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreerow);
+  if (rowContext) {
+    const nsStylePosition* myPosition = rowContext->StylePosition();
+
+    nscoord minHeight = 0;
+    if (myPosition->mMinHeight.GetUnit() == eStyleUnit_Coord)
+      minHeight = myPosition->mMinHeight.GetCoordValue();
+
+    nscoord height = 0;
+    if (myPosition->mHeight.GetUnit() == eStyleUnit_Coord)
+      height = myPosition->mHeight.GetCoordValue();
+
+    if (height < minHeight)
+      height = minHeight;
+
+    if (height > 0) {
+      height = nsPresContext::AppUnitsToIntCSSPixels(height);
+      height += height % 2;
+      height = nsPresContext::CSSPixelsToAppUnits(height);
+
+      // XXX Check box-sizing to determine if border/padding should augment the height
+      // Inflate the height by our margins.
+      nsRect rowRect(0,0,0,height);
+      nsMargin rowMargin;
+      rowContext->StyleMargin()->GetMargin(rowMargin);
+      rowRect.Inflate(rowMargin);
+      height = rowRect.height;
+      return height;
+    }
+  }
+
+  return nsPresContext::CSSPixelsToAppUnits(18); // As good a default as any.
+}
+
+int32_t nsTreeBodyFrame::GetIndentation()
+{
+  // Look up the correct indentation.  It is equal to the specified indentation width.
+  mScratchArray.Clear();
+  nsStyleContext* indentContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreeindentation);
+  if (indentContext) {
+    const nsStylePosition* myPosition = indentContext->StylePosition();
+    if (myPosition->mWidth.GetUnit() == eStyleUnit_Coord)  {
+      nscoord val = myPosition->mWidth.GetCoordValue();
+      return val;
+    }
+  }
+
+  return nsPresContext::CSSPixelsToAppUnits(16); // As good a default as any.
+}
+
+void nsTreeBodyFrame::CalcInnerBox()
+{
+  mInnerBox.SetRect(0, 0, mRect.width, mRect.height);
+  AdjustForBorderPadding(mStyleContext, mInnerBox);
+}
+
+nscoord
+nsTreeBodyFrame::CalcHorzWidth(const ScrollParts& aParts)
+{
+  // Compute the adjustment to the last column. This varies depending on the
+  // visibility of the columnpicker and the scrollbar.
+  if (aParts.mColumnsFrame)
+    mAdjustWidth = mRect.width - aParts.mColumnsFrame->GetRect().width;
+  else
+    mAdjustWidth = 0;
+
+  nscoord width = 0;
+
+  // We calculate this from the scrollable frame, so that it 
+  // properly covers all contingencies of what could be 
+  // scrollable (columns, body, etc...)
+
+  if (aParts.mColumnsScrollFrame) {
+    width = aParts.mColumnsScrollFrame->GetScrollRange().width +
+      aParts.mColumnsScrollFrame->GetScrollPortRect().width;
+  }
+
+  // If no horz scrolling periphery is present, then just return our width
+  if (width == 0)
+    width = mRect.width;
+
+  return width;
+}
+
+nsresult
+nsTreeBodyFrame::GetCursor(const nsPoint& aPoint,
+                           nsIFrame::Cursor& aCursor)
+{
+  // Check the GetScriptHandlingObject so we don't end up running code when
+  // the document is a zombie.
+  bool dummy;
+  if (mView && GetContent()->GetComposedDoc()->GetScriptHandlingObject(dummy)) {
+    int32_t row;
+    nsTreeColumn* col;
+    nsIAtom* child;
+    GetCellAt(aPoint.x, aPoint.y, &row, &col, &child);
+
+    if (child) {
+      // Our scratch array is already prefilled.
+      nsStyleContext* childContext = GetPseudoStyleContext(child);
+
+      FillCursorInformationFromStyle(childContext->StyleUserInterface(),
+                                     aCursor);
+      if (aCursor.mCursor == NS_STYLE_CURSOR_AUTO)
+        aCursor.mCursor = NS_STYLE_CURSOR_DEFAULT;
+
+      return NS_OK;
+    }
+  }
+
+  return nsLeafBoxFrame::GetCursor(aPoint, aCursor);
+}
+
+static uint32_t GetDropEffect(WidgetGUIEvent* aEvent)
+{
+  NS_ASSERTION(aEvent->mClass == eDragEventClass, "wrong event type");
+  WidgetDragEvent* dragEvent = aEvent->AsDragEvent();
+  nsContentUtils::SetDataTransferInEvent(dragEvent);
+
+  uint32_t action = 0;
+  if (dragEvent->mDataTransfer) {
+    dragEvent->mDataTransfer->GetDropEffectInt(&action);
+  }
+  return action;
+}
+
+nsresult
+nsTreeBodyFrame::HandleEvent(nsPresContext* aPresContext,
+                             WidgetGUIEvent* aEvent,
+                             nsEventStatus* aEventStatus)
+{
+  if (aEvent->mMessage == eMouseOver || aEvent->mMessage == eMouseMove) {
+    nsPoint pt = nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, this);
+    int32_t xTwips = pt.x - mInnerBox.x;
+    int32_t yTwips = pt.y - mInnerBox.y;
+    int32_t newrow = GetRowAt(xTwips, yTwips);
+    if (mMouseOverRow != newrow) {
+      // redraw the old and the new row
+      if (mMouseOverRow != -1)
+        InvalidateRow(mMouseOverRow);
+      mMouseOverRow = newrow;
+      if (mMouseOverRow != -1)
+        InvalidateRow(mMouseOverRow);
+    }
+  } else if (aEvent->mMessage == eMouseOut) {
+    if (mMouseOverRow != -1) {
+      InvalidateRow(mMouseOverRow);
+      mMouseOverRow = -1;
+    }
+  } else if (aEvent->mMessage == eDragEnter) {
+    if (!mSlots)
+      mSlots = new Slots();
+
+    // Cache several things we'll need throughout the course of our work. These
+    // will all get released on a drag exit.
+
+    if (mSlots->mTimer) {
+      mSlots->mTimer->Cancel();
+      mSlots->mTimer = nullptr;
+    }
+
+    // Cache the drag session.
+    mSlots->mIsDragging = true;
+    mSlots->mDropRow = -1;
+    mSlots->mDropOrient = -1;
+    mSlots->mDragAction = GetDropEffect(aEvent);
+  } else if (aEvent->mMessage == eDragOver) {
+    // The mouse is hovering over this tree. If we determine things are
+    // different from the last time, invalidate the drop feedback at the old
+    // position, query the view to see if the current location is droppable,
+    // and then invalidate the drop feedback at the new location if it is.
+    // The mouse may or may not have changed position from the last time
+    // we were called, so optimize out a lot of the extra notifications by
+    // checking if anything changed first. For drop feedback we use drop,
+    // dropBefore and dropAfter property.
+
+    if (!mView || !mSlots)
+      return NS_OK;
+
+    // Save last values, we will need them.
+    int32_t lastDropRow = mSlots->mDropRow;
+    int16_t lastDropOrient = mSlots->mDropOrient;
+#ifndef XP_MACOSX
+    int16_t lastScrollLines = mSlots->mScrollLines;
+#endif
+
+    // Find out the current drag action
+    uint32_t lastDragAction = mSlots->mDragAction;
+    mSlots->mDragAction = GetDropEffect(aEvent);
+
+    // Compute the row mouse is over and the above/below/on state.
+    // Below we'll use this to see if anything changed.
+    // Also check if we want to auto-scroll.
+    ComputeDropPosition(aEvent, &mSlots->mDropRow, &mSlots->mDropOrient, &mSlots->mScrollLines);
+
+    // While we're here, handle tracking of scrolling during a drag.
+    if (mSlots->mScrollLines) {
+      if (mSlots->mDropAllowed) {
+        // Invalidate primary cell at old location.
+        mSlots->mDropAllowed = false;
+        InvalidateDropFeedback(lastDropRow, lastDropOrient);
+      }
+#ifdef XP_MACOSX
+      ScrollByLines(mSlots->mScrollLines);
+#else
+      if (!lastScrollLines) {
+        // Cancel any previously initialized timer.
+        if (mSlots->mTimer) {
+          mSlots->mTimer->Cancel();
+          mSlots->mTimer = nullptr;
+        }
+
+        // Set a timer to trigger the tree scrolling.
+        CreateTimer(LookAndFeel::eIntID_TreeLazyScrollDelay,
+                    LazyScrollCallback, nsITimer::TYPE_ONE_SHOT,
+                    getter_AddRefs(mSlots->mTimer));
+       }
+#endif
+      // Bail out to prevent spring loaded timer and feedback line settings.
+      return NS_OK;
+    }
+
+    // If changed from last time, invalidate primary cell at the old location and if allowed, 
+    // invalidate primary cell at the new location. If nothing changed, just bail.
+    if (mSlots->mDropRow != lastDropRow ||
+        mSlots->mDropOrient != lastDropOrient ||
+        mSlots->mDragAction != lastDragAction) {
+
+      // Invalidate row at the old location.
+      if (mSlots->mDropAllowed) {
+        mSlots->mDropAllowed = false;
+        InvalidateDropFeedback(lastDropRow, lastDropOrient);
+      }
+
+      if (mSlots->mTimer) {
+        // Timer is active but for a different row than the current one, kill it.
+        mSlots->mTimer->Cancel();
+        mSlots->mTimer = nullptr;
+      }
+
+      if (mSlots->mDropRow >= 0) {
+        if (!mSlots->mTimer && mSlots->mDropOrient == nsITreeView::DROP_ON) {
+          // Either there wasn't a timer running or it was just killed above.
+          // If over a folder, start up a timer to open the folder.
+          bool isContainer = false;
+          mView->IsContainer(mSlots->mDropRow, &isContainer);
+          if (isContainer) {
+            bool isOpen = false;
+            mView->IsContainerOpen(mSlots->mDropRow, &isOpen);
+            if (!isOpen) {
+              // This node isn't expanded, set a timer to expand it.
+              CreateTimer(LookAndFeel::eIntID_TreeOpenDelay,
+                          OpenCallback, nsITimer::TYPE_ONE_SHOT,
+                          getter_AddRefs(mSlots->mTimer));
+            }
+          }
+        }
+
+        // The dataTransfer was initialized by the call to GetDropEffect above.
+        bool canDropAtNewLocation = false;
+        mView->CanDrop(mSlots->mDropRow, mSlots->mDropOrient,
+                       aEvent->AsDragEvent()->mDataTransfer,
+                       &canDropAtNewLocation);
+
+        if (canDropAtNewLocation) {
+          // Invalidate row at the new location.
+          mSlots->mDropAllowed = canDropAtNewLocation;
+          InvalidateDropFeedback(mSlots->mDropRow, mSlots->mDropOrient);
+        }
+      }
+    }
+
+    // Indicate that the drop is allowed by preventing the default behaviour.
+    if (mSlots->mDropAllowed)
+      *aEventStatus = nsEventStatus_eConsumeNoDefault;
+  } else if (aEvent->mMessage == eDrop) {
+     // this event was meant for another frame, so ignore it
+     if (!mSlots)
+       return NS_OK;
+
+    // Tell the view where the drop happened.
+
+    // Remove the drop folder and all its parents from the array.
+    int32_t parentIndex;
+    nsresult rv = mView->GetParentIndex(mSlots->mDropRow, &parentIndex);
+    while (NS_SUCCEEDED(rv) && parentIndex >= 0) {
+      mSlots->mArray.RemoveElement(parentIndex);
+      rv = mView->GetParentIndex(parentIndex, &parentIndex);
+    }
+
+    NS_ASSERTION(aEvent->mClass == eDragEventClass, "wrong event type");
+    WidgetDragEvent* dragEvent = aEvent->AsDragEvent();
+    nsContentUtils::SetDataTransferInEvent(dragEvent);
+
+    mView->Drop(mSlots->mDropRow, mSlots->mDropOrient,
+                dragEvent->mDataTransfer);
+    mSlots->mDropRow = -1;
+    mSlots->mDropOrient = -1;
+    mSlots->mIsDragging = false;
+    *aEventStatus = nsEventStatus_eConsumeNoDefault; // already handled the drop
+  } else if (aEvent->mMessage == eDragExit) {
+    // this event was meant for another frame, so ignore it
+    if (!mSlots)
+      return NS_OK;
+
+    // Clear out all our tracking vars.
+
+    if (mSlots->mDropAllowed) {
+      mSlots->mDropAllowed = false;
+      InvalidateDropFeedback(mSlots->mDropRow, mSlots->mDropOrient);
+    }
+    else
+      mSlots->mDropAllowed = false;
+    mSlots->mIsDragging = false;
+    mSlots->mScrollLines = 0;
+    // If a drop is occuring, the exit event will fire just before the drop
+    // event, so don't reset mDropRow or mDropOrient as these fields are used
+    // by the drop event.
+    if (mSlots->mTimer) {
+      mSlots->mTimer->Cancel();
+      mSlots->mTimer = nullptr;
+    }
+
+    if (!mSlots->mArray.IsEmpty()) {
+      // Close all spring loaded folders except the drop folder.
+      CreateTimer(LookAndFeel::eIntID_TreeCloseDelay,
+                  CloseCallback, nsITimer::TYPE_ONE_SHOT,
+                  getter_AddRefs(mSlots->mTimer));
+    }
+  }
+
+  return NS_OK;
+}
+
+class nsDisplayTreeBody final : public nsDisplayItem {
+public:
+  nsDisplayTreeBody(nsDisplayListBuilder* aBuilder, nsFrame* aFrame) :
+    nsDisplayItem(aBuilder, aFrame),
+    mDisableSubpixelAA(false) {
+    MOZ_COUNT_CTOR(nsDisplayTreeBody);
+  }
+#ifdef NS_BUILD_REFCNT_LOGGING
+  virtual ~nsDisplayTreeBody() {
+    MOZ_COUNT_DTOR(nsDisplayTreeBody);
+  }
+#endif
+
+  nsDisplayItemGeometry* AllocateGeometry(nsDisplayListBuilder* aBuilder) override
+  {
+    return new nsDisplayItemGenericImageGeometry(this, aBuilder);
+  }
+
+  void ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
+                                 const nsDisplayItemGeometry* aGeometry,
+                                 nsRegion *aInvalidRegion) override
+  {
+    auto geometry =
+      static_cast<const nsDisplayItemGenericImageGeometry*>(aGeometry);
+
+    if (aBuilder->ShouldSyncDecodeImages() &&
+        geometry->ShouldInvalidateToSyncDecodeImages()) {
+      bool snap;
+      aInvalidRegion->Or(*aInvalidRegion, GetBounds(aBuilder, &snap));
+    }
+
+    nsDisplayItem::ComputeInvalidationRegion(aBuilder, aGeometry, aInvalidRegion);
+  }
+
+  virtual void Paint(nsDisplayListBuilder* aBuilder,
+                     nsRenderingContext* aCtx) override
+  {
+    DrawTargetAutoDisableSubpixelAntialiasing disable(aCtx->GetDrawTarget(),
+                                                      mDisableSubpixelAA);
+
+    DrawResult result = static_cast<nsTreeBodyFrame*>(mFrame)
+      ->PaintTreeBody(*aCtx, mVisibleRect, ToReferenceFrame());
+
+    nsDisplayItemGenericImageGeometry::UpdateDrawResult(this, result);
+  }
+
+  NS_DISPLAY_DECL_NAME("XULTreeBody", TYPE_XUL_TREE_BODY)
+
+  virtual nsRect GetComponentAlphaBounds(nsDisplayListBuilder* aBuilder) override
+  {
+    bool snap;
+    return GetBounds(aBuilder, &snap);
+  }
+  virtual void DisableComponentAlpha() override {
+    mDisableSubpixelAA = true;
+  }
+
+  bool mDisableSubpixelAA;
+};
+
+// Painting routines
+void
+nsTreeBodyFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                  const nsRect&           aDirtyRect,
+                                  const nsDisplayListSet& aLists)
+{
+  // REVIEW: why did we paint if we were collapsed? that makes no sense!
+  if (!IsVisibleForPainting(aBuilder))
+    return; // We're invisible.  Don't paint.
+
+  // Handles painting our background, border, and outline.
+  nsLeafBoxFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);
+
+  // Bail out now if there's no view or we can't run script because the
+  // document is a zombie
+  if (!mView || !GetContent ()->GetComposedDoc()->GetWindow())
+    return;
+
+#ifdef XP_MACOSX
+  nsIContent* baseElement = GetBaseElement();
+  nsIFrame* treeFrame =
+    baseElement ? baseElement->GetPrimaryFrame() : nullptr;
+  nsCOMPtr<nsITreeSelection> selection;
+  mView->GetSelection(getter_AddRefs(selection));
+  nsITheme* theme = PresContext()->GetTheme();
+  // On Mac, we support native theming of selected rows. On 10.10 and higher,
+  // this means applying vibrancy which require us to register the theme
+  // geometrics for the row. In order to make the vibrancy effect to work
+  // properly, we also need the tree to be themed as a source list.
+  if (selection && treeFrame && theme &&
+      treeFrame->StyleDisplay()->mAppearance == NS_THEME_MAC_SOURCE_LIST) {
+    // Loop through our onscreen rows. If the row is selected and a
+    // -moz-appearance is provided, RegisterThemeGeometry might be necessary.
+    const auto end = std::min(mRowCount, LastVisibleRow() + 1);
+    for (auto i = FirstVisibleRow(); i < end; i++) {
+      bool isSelected;
+      selection->IsSelected(i, &isSelected);
+      if (isSelected) {
+        PrefillPropertyArray(i, nullptr);
+        nsAutoString properties;
+        mView->GetRowProperties(i, properties);
+        nsTreeUtils::TokenizeProperties(properties, mScratchArray);
+        nsStyleContext* rowContext =
+          GetPseudoStyleContext(nsCSSAnonBoxes::moztreerow);
+        auto appearance = rowContext->StyleDisplay()->mAppearance;
+        if (appearance) {
+          if (theme->ThemeSupportsWidget(PresContext(), this, appearance)) {
+            nsITheme::ThemeGeometryType type =
+              theme->ThemeGeometryTypeForWidget(this, appearance);
+            if (type != nsITheme::eThemeGeometryTypeUnknown) {
+              nsRect rowRect(mInnerBox.x, mInnerBox.y + mRowHeight *
+                             (i - FirstVisibleRow()), mInnerBox.width,
+                             mRowHeight);
+              aBuilder->RegisterThemeGeometry(type,
+                LayoutDeviceIntRect::FromUnknownRect(
+                  (rowRect + aBuilder->ToReferenceFrame(this)).ToNearestPixels(
+                    PresContext()->AppUnitsPerDevPixel())));
+            }
+          }
+        }
+      }
+    }
+  }
+#endif
+
+  aLists.Content()->AppendNewToTop(new (aBuilder)
+    nsDisplayTreeBody(aBuilder, this));
+}
+
+DrawResult
+nsTreeBodyFrame::PaintTreeBody(nsRenderingContext& aRenderingContext,
+                               const nsRect& aDirtyRect, nsPoint aPt)
+{
+  // Update our available height and our page count.
+  CalcInnerBox();
+
+  DrawTarget* drawTarget = aRenderingContext.GetDrawTarget();
+  gfxContext* gfx = aRenderingContext.ThebesContext();
+
+  gfx->Save();
+  gfx->Clip(NSRectToSnappedRect(mInnerBox + aPt,
+                                PresContext()->AppUnitsPerDevPixel(),
+                                *drawTarget));
+  int32_t oldPageCount = mPageLength;
+  if (!mHasFixedRowCount)
+    mPageLength = mInnerBox.height/mRowHeight;
+
+  if (oldPageCount != mPageLength || mHorzWidth != CalcHorzWidth(GetScrollParts())) {
+    // Schedule a ResizeReflow that will update our info properly.
+    PresContext()->PresShell()->
+      FrameNeedsReflow(this, nsIPresShell::eResize, NS_FRAME_IS_DIRTY);
+  }
+#ifdef DEBUG
+  int32_t rowCount = mRowCount;
+  mView->GetRowCount(&rowCount);
+  NS_WARNING_ASSERTION(mRowCount == rowCount, "row count changed unexpectedly");
+#endif
+
+  DrawResult result = DrawResult::SUCCESS;
+
+  // Loop through our columns and paint them (e.g., for sorting).  This is only
+  // relevant when painting backgrounds, since columns contain no content.  Content
+  // is contained in the rows.
+  for (nsTreeColumn* currCol = mColumns->GetFirstColumn(); currCol;
+       currCol = currCol->GetNext()) {
+    nsRect colRect;
+    nsresult rv = currCol->GetRect(this, mInnerBox.y, mInnerBox.height,
+                                   &colRect);
+    // Don't paint hidden columns.
+    if (NS_FAILED(rv) || colRect.width == 0) continue;
+
+    if (OffsetForHorzScroll(colRect, false)) {
+      nsRect dirtyRect;
+      colRect += aPt;
+      if (dirtyRect.IntersectRect(aDirtyRect, colRect)) {
+        result &=
+          PaintColumn(currCol, colRect, PresContext(), aRenderingContext, aDirtyRect);
+      }
+    }
+  }
+  // Loop through our on-screen rows.
+  for (int32_t i = mTopRowIndex; i < mRowCount && i <= mTopRowIndex+mPageLength; i++) {
+    nsRect rowRect(mInnerBox.x, mInnerBox.y+mRowHeight*(i-mTopRowIndex), mInnerBox.width, mRowHeight);
+    nsRect dirtyRect;
+    if (dirtyRect.IntersectRect(aDirtyRect, rowRect + aPt) &&
+        rowRect.y < (mInnerBox.y+mInnerBox.height)) {
+      result &=
+        PaintRow(i, rowRect + aPt, PresContext(), aRenderingContext, aDirtyRect, aPt);
+    }
+  }
+
+  if (mSlots && mSlots->mDropAllowed && (mSlots->mDropOrient == nsITreeView::DROP_BEFORE ||
+      mSlots->mDropOrient == nsITreeView::DROP_AFTER)) {
+    nscoord yPos = mInnerBox.y + mRowHeight * (mSlots->mDropRow - mTopRowIndex) - mRowHeight / 2;
+    nsRect feedbackRect(mInnerBox.x, yPos, mInnerBox.width, mRowHeight);
+    if (mSlots->mDropOrient == nsITreeView::DROP_AFTER)
+      feedbackRect.y += mRowHeight;
+
+    nsRect dirtyRect;
+    feedbackRect += aPt;
+    if (dirtyRect.IntersectRect(aDirtyRect, feedbackRect)) {
+      result &=
+        PaintDropFeedback(feedbackRect, PresContext(), aRenderingContext,
+                          aDirtyRect, aPt);
+    }
+  }
+  gfx->Restore();
+
+  return result;
+}
+
+
+
+DrawResult
+nsTreeBodyFrame::PaintColumn(nsTreeColumn*        aColumn,
+                             const nsRect&        aColumnRect,
+                             nsPresContext*      aPresContext,
+                             nsRenderingContext& aRenderingContext,
+                             const nsRect&        aDirtyRect)
+{
+  NS_PRECONDITION(aColumn && aColumn->GetFrame(), "invalid column passed");
+
+  // Now obtain the properties for our cell.
+  PrefillPropertyArray(-1, aColumn);
+  nsAutoString properties;
+  mView->GetColumnProperties(aColumn, properties);
+  nsTreeUtils::TokenizeProperties(properties, mScratchArray);
+
+  // Resolve style for the column.  It contains all the info we need to lay ourselves
+  // out and to paint.
+  nsStyleContext* colContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecolumn);
+
+  // Obtain the margins for the cell and then deflate our rect by that 
+  // amount.  The cell is assumed to be contained within the deflated rect.
+  nsRect colRect(aColumnRect);
+  nsMargin colMargin;
+  colContext->StyleMargin()->GetMargin(colMargin);
+  colRect.Deflate(colMargin);
+
+  return PaintBackgroundLayer(colContext, aPresContext, aRenderingContext,
+                              colRect, aDirtyRect);
+}
+
+DrawResult
+nsTreeBodyFrame::PaintRow(int32_t              aRowIndex,
+                          const nsRect&        aRowRect,
+                          nsPresContext*       aPresContext,
+                          nsRenderingContext& aRenderingContext,
+                          const nsRect&        aDirtyRect,
+                          nsPoint              aPt)
+{
+  // We have been given a rect for our row.  We treat this row like a full-blown
+  // frame, meaning that it can have borders, margins, padding, and a background.
+  
+  // Without a view, we have no data. Check for this up front.
+  if (!mView) {
+    return DrawResult::SUCCESS;
+  }
+
+  nsresult rv;
+
+  // Now obtain the properties for our row.
+  // XXX Automatically fill in the following props: open, closed, container, leaf, selected, focused
+  PrefillPropertyArray(aRowIndex, nullptr);
+
+  nsAutoString properties;
+  mView->GetRowProperties(aRowIndex, properties);
+  nsTreeUtils::TokenizeProperties(properties, mScratchArray);
+
+  // Resolve style for the row.  It contains all the info we need to lay ourselves
+  // out and to paint.
+  nsStyleContext* rowContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreerow);
+
+  // Obtain the margins for the row and then deflate our rect by that 
+  // amount.  The row is assumed to be contained within the deflated rect.
+  nsRect rowRect(aRowRect);
+  nsMargin rowMargin;
+  rowContext->StyleMargin()->GetMargin(rowMargin);
+  rowRect.Deflate(rowMargin);
+
+  DrawResult result = DrawResult::SUCCESS;
+
+  // Paint our borders and background for our row rect.
+  nsITheme* theme = nullptr;
+  auto appearance = rowContext->StyleDisplay()->mAppearance;
+  if (appearance) {
+    theme = aPresContext->GetTheme();
+  }
+  gfxContext* ctx = aRenderingContext.ThebesContext();
+  // Save the current font smoothing background color in case we change it.
+  Color originalColor(ctx->GetFontSmoothingBackgroundColor());
+  if (theme && theme->ThemeSupportsWidget(aPresContext, nullptr, appearance)) {
+    nscolor color;
+    if (theme->WidgetProvidesFontSmoothingBackgroundColor(this, appearance,
+                                                          &color)) {
+      // Set the font smoothing background color provided by the widget.
+      ctx->SetFontSmoothingBackgroundColor(ToDeviceColor(color));
+    }
+    nsRect dirty;
+    dirty.IntersectRect(rowRect, aDirtyRect);
+    theme->DrawWidgetBackground(&aRenderingContext, this, appearance, rowRect,
+                                dirty);
+  } else {
+    result &= PaintBackgroundLayer(rowContext, aPresContext, aRenderingContext,
+                                   rowRect, aDirtyRect);
+  }
+  
+  // Adjust the rect for its border and padding.
+  nsRect originalRowRect = rowRect;
+  AdjustForBorderPadding(rowContext, rowRect);
+
+  bool isSeparator = false;
+  mView->IsSeparator(aRowIndex, &isSeparator);
+  if (isSeparator) {
+    // The row is a separator.
+
+    nscoord primaryX = rowRect.x;
+    nsTreeColumn* primaryCol = mColumns->GetPrimaryColumn();
+    if (primaryCol) {
+      // Paint the primary cell.
+      nsRect cellRect;
+      rv = primaryCol->GetRect(this, rowRect.y, rowRect.height, &cellRect);
+      if (NS_FAILED(rv)) {
+        NS_NOTREACHED("primary column is invalid");
+        return result;
+      }
+
+      if (OffsetForHorzScroll(cellRect, false)) {
+        cellRect.x += aPt.x;
+        nsRect dirtyRect;
+        nsRect checkRect(cellRect.x, originalRowRect.y,
+                         cellRect.width, originalRowRect.height);
+        if (dirtyRect.IntersectRect(aDirtyRect, checkRect)) {
+          result &= PaintCell(aRowIndex, primaryCol, cellRect, aPresContext,
+                              aRenderingContext, aDirtyRect, primaryX, aPt);
+        }
+      }
+
+      // Paint the left side of the separator.
+      nscoord currX;
+      nsTreeColumn* previousCol = primaryCol->GetPrevious();
+      if (previousCol) {
+        nsRect prevColRect;
+        rv = previousCol->GetRect(this, 0, 0, &prevColRect);
+        if (NS_SUCCEEDED(rv)) {
+          currX = (prevColRect.x - mHorzPosition) + prevColRect.width + aPt.x;
+        } else {
+          NS_NOTREACHED("The column before the primary column is invalid");
+          currX = rowRect.x;
+        }
+      } else {
+        currX = rowRect.x;
+      }
+
+      int32_t level;
+      mView->GetLevel(aRowIndex, &level);
+      if (level == 0)
+        currX += mIndentation;
+
+      if (currX > rowRect.x) {
+        nsRect separatorRect(rowRect);
+        separatorRect.width -= rowRect.x + rowRect.width - currX;
+        result &= PaintSeparator(aRowIndex, separatorRect, aPresContext,
+                                 aRenderingContext, aDirtyRect);
+      }
+    }
+
+    // Paint the right side (whole) separator.
+    nsRect separatorRect(rowRect);
+    if (primaryX > rowRect.x) {
+      separatorRect.width -= primaryX - rowRect.x;
+      separatorRect.x += primaryX - rowRect.x;
+    }
+    result &= PaintSeparator(aRowIndex, separatorRect, aPresContext,
+                             aRenderingContext, aDirtyRect);
+  }
+  else {
+    // Now loop over our cells. Only paint a cell if it intersects with our dirty rect.
+    for (nsTreeColumn* currCol = mColumns->GetFirstColumn(); currCol;
+         currCol = currCol->GetNext()) {
+      nsRect cellRect;
+      rv = currCol->GetRect(this, rowRect.y, rowRect.height, &cellRect);
+      // Don't paint cells in hidden columns.
+      if (NS_FAILED(rv) || cellRect.width == 0)
+        continue;
+
+      if (OffsetForHorzScroll(cellRect, false)) {
+        cellRect.x += aPt.x;
+
+        // for primary columns, use the row's vertical size so that the
+        // lines get drawn properly
+        nsRect checkRect = cellRect;
+        if (currCol->IsPrimary())
+          checkRect = nsRect(cellRect.x, originalRowRect.y,
+                             cellRect.width, originalRowRect.height);
+
+        nsRect dirtyRect;
+        nscoord dummy;
+        if (dirtyRect.IntersectRect(aDirtyRect, checkRect))
+          result &= PaintCell(aRowIndex, currCol, cellRect, aPresContext,
+                              aRenderingContext, aDirtyRect, dummy, aPt);
+      }
+    }
+  }
+  // If we've changed the font smoothing background color for this row, restore
+  // the color to the original one.
+  if (originalColor != ctx->GetFontSmoothingBackgroundColor()) {
+    ctx->SetFontSmoothingBackgroundColor(originalColor);
+  }
+
+  return result;
+}
+
+DrawResult
+nsTreeBodyFrame::PaintSeparator(int32_t              aRowIndex,
+                                const nsRect&        aSeparatorRect,
+                                nsPresContext*      aPresContext,
+                                nsRenderingContext& aRenderingContext,
+                                const nsRect&        aDirtyRect)
+{
+  // Resolve style for the separator.
+  nsStyleContext* separatorContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreeseparator);
+  bool useTheme = false;
+  nsITheme *theme = nullptr;
+  const nsStyleDisplay* displayData = separatorContext->StyleDisplay();
+  if ( displayData->mAppearance ) {
+    theme = aPresContext->GetTheme();
+    if (theme && theme->ThemeSupportsWidget(aPresContext, nullptr, displayData->mAppearance))
+      useTheme = true;
+  }
+
+  DrawResult result = DrawResult::SUCCESS;
+
+  // use -moz-appearance if provided.
+  if (useTheme) {
+    nsRect dirty;
+    dirty.IntersectRect(aSeparatorRect, aDirtyRect);
+    theme->DrawWidgetBackground(&aRenderingContext, this,
+                                displayData->mAppearance, aSeparatorRect, dirty); 
+  }
+  else {
+    const nsStylePosition* stylePosition = separatorContext->StylePosition();
+
+    // Obtain the height for the separator or use the default value.
+    nscoord height;
+    if (stylePosition->mHeight.GetUnit() == eStyleUnit_Coord)
+      height = stylePosition->mHeight.GetCoordValue();
+    else {
+      // Use default height 2px.
+      height = nsPresContext::CSSPixelsToAppUnits(2);
+    }
+
+    // Obtain the margins for the separator and then deflate our rect by that 
+    // amount. The separator is assumed to be contained within the deflated rect.
+    nsRect separatorRect(aSeparatorRect.x, aSeparatorRect.y, aSeparatorRect.width, height);
+    nsMargin separatorMargin;
+    separatorContext->StyleMargin()->GetMargin(separatorMargin);
+    separatorRect.Deflate(separatorMargin);
+
+    // Center the separator.
+    separatorRect.y += (aSeparatorRect.height - height) / 2;
+
+    result &= PaintBackgroundLayer(separatorContext, aPresContext,
+                                   aRenderingContext, separatorRect,
+                                   aDirtyRect);
+  }
+
+  return result;
+}
+
+DrawResult
+nsTreeBodyFrame::PaintCell(int32_t              aRowIndex,
+                           nsTreeColumn*        aColumn,
+                           const nsRect&        aCellRect,
+                           nsPresContext*       aPresContext,
+                           nsRenderingContext& aRenderingContext,
+                           const nsRect&        aDirtyRect,
+                           nscoord&             aCurrX,
+                           nsPoint              aPt)
+{
+  NS_PRECONDITION(aColumn && aColumn->GetFrame(), "invalid column passed");
+
+  // Now obtain the properties for our cell.
+  // XXX Automatically fill in the following props: open, closed, container, leaf, selected, focused, and the col ID.
+  PrefillPropertyArray(aRowIndex, aColumn);
+  nsAutoString properties;
+  mView->GetCellProperties(aRowIndex, aColumn, properties);
+  nsTreeUtils::TokenizeProperties(properties, mScratchArray);
+
+  // Resolve style for the cell.  It contains all the info we need to lay ourselves
+  // out and to paint.
+  nsStyleContext* cellContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecell);
+
+  bool isRTL = StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
+
+  // Obtain the margins for the cell and then deflate our rect by that 
+  // amount.  The cell is assumed to be contained within the deflated rect.
+  nsRect cellRect(aCellRect);
+  nsMargin cellMargin;
+  cellContext->StyleMargin()->GetMargin(cellMargin);
+  cellRect.Deflate(cellMargin);
+
+  // Paint our borders and background for our row rect.
+  DrawResult result = PaintBackgroundLayer(cellContext, aPresContext,
+                                           aRenderingContext, cellRect,
+                                           aDirtyRect);
+
+  // Adjust the rect for its border and padding.
+  AdjustForBorderPadding(cellContext, cellRect);
+
+  nscoord currX = cellRect.x;
+  nscoord remainingWidth = cellRect.width;
+
+  // Now we paint the contents of the cells.
+  // Directionality of the tree determines the order in which we paint.  
+  // NS_STYLE_DIRECTION_LTR means paint from left to right.
+  // NS_STYLE_DIRECTION_RTL means paint from right to left.
+
+  if (aColumn->IsPrimary()) {
+    // If we're the primary column, we need to indent and paint the twisty and any connecting lines
+    // between siblings.
+
+    int32_t level;
+    mView->GetLevel(aRowIndex, &level);
+
+    if (!isRTL)
+      currX += mIndentation * level;
+    remainingWidth -= mIndentation * level;
+
+    // Resolve the style to use for the connecting lines.
+    nsStyleContext* lineContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreeline);
+    
+    if (mIndentation && level &&
+        lineContext->StyleVisibility()->IsVisibleOrCollapsed()) {
+      // Paint the thread lines.
+
+      // Get the size of the twisty. We don't want to paint the twisty
+      // before painting of connecting lines since it would paint lines over
+      // the twisty. But we need to leave a place for it.
+      nsStyleContext* twistyContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreetwisty);
+
+      nsRect imageSize;
+      nsRect twistyRect(aCellRect);
+      GetTwistyRect(aRowIndex, aColumn, imageSize, twistyRect, aPresContext,
+                    twistyContext);
+
+      nsMargin twistyMargin;
+      twistyContext->StyleMargin()->GetMargin(twistyMargin);
+      twistyRect.Inflate(twistyMargin);
+
+      aRenderingContext.ThebesContext()->Save();
+
+      const nsStyleBorder* borderStyle = lineContext->StyleBorder();
+      // Resolve currentcolor values against the treeline context
+      nscolor color = lineContext->StyleColor()->
+        CalcComplexColor(borderStyle->mBorderLeftColor);
+      ColorPattern colorPatt(ToDeviceColor(color));
+
+      uint8_t style = borderStyle->GetBorderStyle(NS_SIDE_LEFT);
+      StrokeOptions strokeOptions;
+      nsLayoutUtils::InitDashPattern(strokeOptions, style);
+
+      nscoord srcX = currX + twistyRect.width - mIndentation / 2;
+      nscoord lineY = (aRowIndex - mTopRowIndex) * mRowHeight + aPt.y;
+
+      DrawTarget* drawTarget = aRenderingContext.GetDrawTarget();
+      nsPresContext* pc = PresContext();
+
+      // Don't paint off our cell.
+      if (srcX <= cellRect.x + cellRect.width) {
+        nscoord destX = currX + twistyRect.width;
+        if (destX > cellRect.x + cellRect.width)
+          destX = cellRect.x + cellRect.width;
+        if (isRTL) {
+          srcX = currX + remainingWidth - (srcX - cellRect.x);
+          destX = currX + remainingWidth - (destX - cellRect.x);
+        }
+        Point p1(pc->AppUnitsToGfxUnits(srcX),
+                 pc->AppUnitsToGfxUnits(lineY + mRowHeight / 2));
+        Point p2(pc->AppUnitsToGfxUnits(destX),
+                 pc->AppUnitsToGfxUnits(lineY + mRowHeight / 2));
+        SnapLineToDevicePixelsForStroking(p1, p2, *drawTarget,
+                                          strokeOptions.mLineWidth);
+        drawTarget->StrokeLine(p1, p2, colorPatt, strokeOptions);
+      }
+
+      int32_t currentParent = aRowIndex;
+      for (int32_t i = level; i > 0; i--) {
+        if (srcX <= cellRect.x + cellRect.width) {
+          // Paint full vertical line only if we have next sibling.
+          bool hasNextSibling;
+          mView->HasNextSibling(currentParent, aRowIndex, &hasNextSibling);
+          if (hasNextSibling || i == level) {
+            Point p1(pc->AppUnitsToGfxUnits(srcX),
+                     pc->AppUnitsToGfxUnits(lineY));
+            Point p2;
+            p2.x = pc->AppUnitsToGfxUnits(srcX);
+
+            if (hasNextSibling)
+              p2.y = pc->AppUnitsToGfxUnits(lineY + mRowHeight);
+            else if (i == level)
+              p2.y = pc->AppUnitsToGfxUnits(lineY + mRowHeight / 2);
+
+            SnapLineToDevicePixelsForStroking(p1, p2, *drawTarget,
+                                              strokeOptions.mLineWidth);
+            drawTarget->StrokeLine(p1, p2, colorPatt, strokeOptions);
+          }          
+        }
+
+        int32_t parent;
+        if (NS_FAILED(mView->GetParentIndex(currentParent, &parent)) || parent < 0)
+          break;
+        currentParent = parent;
+        srcX -= mIndentation;
+      }
+
+      aRenderingContext.ThebesContext()->Restore();
+    }
+
+    // Always leave space for the twisty.
+    nsRect twistyRect(currX, cellRect.y, remainingWidth, cellRect.height);
+    result &= PaintTwisty(aRowIndex, aColumn, twistyRect, aPresContext,
+                          aRenderingContext, aDirtyRect, remainingWidth,
+                          currX);
+  }
+  
+  // Now paint the icon for our cell.
+  nsRect iconRect(currX, cellRect.y, remainingWidth, cellRect.height);
+  nsRect dirtyRect;
+  if (dirtyRect.IntersectRect(aDirtyRect, iconRect)) {
+    result &= PaintImage(aRowIndex, aColumn, iconRect, aPresContext,
+                         aRenderingContext, aDirtyRect, remainingWidth,
+                         currX);
+  }
+
+  // Now paint our element, but only if we aren't a cycler column.
+  // XXX until we have the ability to load images, allow the view to 
+  // insert text into cycler columns...
+  if (!aColumn->IsCycler()) {
+    nsRect elementRect(currX, cellRect.y, remainingWidth, cellRect.height);
+    nsRect dirtyRect;
+    if (dirtyRect.IntersectRect(aDirtyRect, elementRect)) {
+      switch (aColumn->GetType()) {
+        case nsITreeColumn::TYPE_TEXT:
+        case nsITreeColumn::TYPE_PASSWORD:
+          result &= PaintText(aRowIndex, aColumn, elementRect, aPresContext,
+                              aRenderingContext, aDirtyRect, currX);
+          break;
+        case nsITreeColumn::TYPE_CHECKBOX:
+          result &= PaintCheckbox(aRowIndex, aColumn, elementRect, aPresContext,
+                                  aRenderingContext, aDirtyRect);
+          break;
+        case nsITreeColumn::TYPE_PROGRESSMETER:
+          int32_t state;
+          mView->GetProgressMode(aRowIndex, aColumn, &state);
+          switch (state) {
+            case nsITreeView::PROGRESS_NORMAL:
+            case nsITreeView::PROGRESS_UNDETERMINED:
+              result &= PaintProgressMeter(aRowIndex, aColumn, elementRect,
+                                           aPresContext, aRenderingContext,
+                                           aDirtyRect);
+              break;
+            case nsITreeView::PROGRESS_NONE:
+            default:
+              result &= PaintText(aRowIndex, aColumn, elementRect, aPresContext,
+                                  aRenderingContext, aDirtyRect, currX);
+              break;
+          }
+          break;
+      }
+    }
+  }
+
+  aCurrX = currX;
+
+  return result;
+}
+
+DrawResult
+nsTreeBodyFrame::PaintTwisty(int32_t              aRowIndex,
+                             nsTreeColumn*        aColumn,
+                             const nsRect&        aTwistyRect,
+                             nsPresContext*      aPresContext,
+                             nsRenderingContext& aRenderingContext,
+                             const nsRect&        aDirtyRect,
+                             nscoord&             aRemainingWidth,
+                             nscoord&             aCurrX)
+{
+  NS_PRECONDITION(aColumn && aColumn->GetFrame(), "invalid column passed");
+
+  bool isRTL = StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
+  nscoord rightEdge = aCurrX + aRemainingWidth;
+  // Paint the twisty, but only if we are a non-empty container.
+  bool shouldPaint = false;
+  bool isContainer = false;
+  mView->IsContainer(aRowIndex, &isContainer);
+  if (isContainer) {
+    bool isContainerEmpty = false;
+    mView->IsContainerEmpty(aRowIndex, &isContainerEmpty);
+    if (!isContainerEmpty)
+      shouldPaint = true;
+  }
+
+  // Resolve style for the twisty.
+  nsStyleContext* twistyContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreetwisty);
+
+  // Obtain the margins for the twisty and then deflate our rect by that 
+  // amount.  The twisty is assumed to be contained within the deflated rect.
+  nsRect twistyRect(aTwistyRect);
+  nsMargin twistyMargin;
+  twistyContext->StyleMargin()->GetMargin(twistyMargin);
+  twistyRect.Deflate(twistyMargin);
+
+  nsRect imageSize;
+  nsITheme* theme = GetTwistyRect(aRowIndex, aColumn, imageSize, twistyRect,
+                                  aPresContext, twistyContext);
+
+  // Subtract out the remaining width.  This is done even when we don't actually paint a twisty in 
+  // this cell, so that cells in different rows still line up.
+  nsRect copyRect(twistyRect);
+  copyRect.Inflate(twistyMargin);
+  aRemainingWidth -= copyRect.width;
+  if (!isRTL)
+    aCurrX += copyRect.width;
+
+  DrawResult result = DrawResult::SUCCESS;
+
+  if (shouldPaint) {
+    // Paint our borders and background for our image rect.
+    result &= PaintBackgroundLayer(twistyContext, aPresContext,
+                                   aRenderingContext, twistyRect,
+                                   aDirtyRect);
+
+    if (theme) {
+      if (isRTL)
+        twistyRect.x = rightEdge - twistyRect.width;
+      // yeah, I know it says we're drawing a background, but a twisty is really a fg
+      // object since it doesn't have anything that gecko would want to draw over it. Besides,
+      // we have to prevent imagelib from drawing it.
+      nsRect dirty;
+      dirty.IntersectRect(twistyRect, aDirtyRect);
+      theme->DrawWidgetBackground(&aRenderingContext, this, 
+                                  twistyContext->StyleDisplay()->mAppearance, twistyRect, dirty);
+    }
+    else {
+      // Time to paint the twisty.
+      // Adjust the rect for its border and padding.
+      nsMargin bp(0,0,0,0);
+      GetBorderPadding(twistyContext, bp);
+      twistyRect.Deflate(bp);
+      if (isRTL)
+        twistyRect.x = rightEdge - twistyRect.width;
+      imageSize.Deflate(bp);
+
+      // Get the image for drawing.
+      nsCOMPtr<imgIContainer> image;
+      bool useImageRegion = true;
+      GetImage(aRowIndex, aColumn, true, twistyContext, useImageRegion, getter_AddRefs(image));
+      if (image) {
+        nsPoint pt = twistyRect.TopLeft();
+
+        // Center the image. XXX Obey vertical-align style prop?
+        if (imageSize.height < twistyRect.height) {
+          pt.y += (twistyRect.height - imageSize.height)/2;
+        }
+
+        // Paint the image.
+        result &=
+          nsLayoutUtils::DrawSingleUnscaledImage(
+              *aRenderingContext.ThebesContext(), aPresContext, image,
+              SamplingFilter::POINT, pt, &aDirtyRect,
+              imgIContainer::FLAG_NONE, &imageSize);
+      }
+    }
+  }
+
+  return result;
+}
+
+DrawResult
+nsTreeBodyFrame::PaintImage(int32_t              aRowIndex,
+                            nsTreeColumn*        aColumn,
+                            const nsRect&        aImageRect,
+                            nsPresContext*       aPresContext,
+                            nsRenderingContext& aRenderingContext,
+                            const nsRect&        aDirtyRect,
+                            nscoord&             aRemainingWidth,
+                            nscoord&             aCurrX)
+{
+  NS_PRECONDITION(aColumn && aColumn->GetFrame(), "invalid column passed");
+
+  bool isRTL = StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
+  nscoord rightEdge = aCurrX + aRemainingWidth;
+  // Resolve style for the image.
+  nsStyleContext* imageContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreeimage);
+
+  // Obtain opacity value for the image.
+  float opacity = imageContext->StyleEffects()->mOpacity;
+
+  // Obtain the margins for the image and then deflate our rect by that
+  // amount.  The image is assumed to be contained within the deflated rect.
+  nsRect imageRect(aImageRect);
+  nsMargin imageMargin;
+  imageContext->StyleMargin()->GetMargin(imageMargin);
+  imageRect.Deflate(imageMargin);
+
+  // Get the image.
+  bool useImageRegion = true;
+  nsCOMPtr<imgIContainer> image;
+  GetImage(aRowIndex, aColumn, false, imageContext, useImageRegion, getter_AddRefs(image));
+
+  // Get the image destination size.
+  nsSize imageDestSize = GetImageDestSize(imageContext, useImageRegion, image);
+  if (!imageDestSize.width || !imageDestSize.height) {
+    return DrawResult::SUCCESS;
+  }
+
+  // Get the borders and padding.
+  nsMargin bp(0,0,0,0);
+  GetBorderPadding(imageContext, bp);
+
+  // destRect will be passed as the aDestRect argument in the DrawImage method.
+  // Start with the imageDestSize width and height.
+  nsRect destRect(0, 0, imageDestSize.width, imageDestSize.height);
+  // Inflate destRect for borders and padding so that we can compare/adjust
+  // with respect to imageRect.
+  destRect.Inflate(bp);
+
+  // The destRect width and height have not been adjusted to fit within the
+  // cell width and height.
+  // We must adjust the width even if image is null, because the width is used
+  // to update the aRemainingWidth and aCurrX values.
+  // Since the height isn't used unless the image is not null, we will adjust
+  // the height inside the if (image) block below.
+
+  if (destRect.width > imageRect.width) {
+    // The destRect is too wide to fit within the cell width.
+    // Adjust destRect width to fit within the cell width.
+    destRect.width = imageRect.width;
+  }
+  else {
+    // The cell is wider than the destRect.
+    // In a cycler column, the image is centered horizontally.
+    if (!aColumn->IsCycler()) {
+      // If this column is not a cycler, we won't center the image horizontally.
+      // We adjust the imageRect width so that the image is placed at the start
+      // of the cell.
+      imageRect.width = destRect.width;
+    }
+  }
+
+  DrawResult result = DrawResult::SUCCESS;
+
+  if (image) {
+    if (isRTL)
+      imageRect.x = rightEdge - imageRect.width;
+    // Paint our borders and background for our image rect
+    result &= PaintBackgroundLayer(imageContext, aPresContext,
+                                   aRenderingContext, imageRect,
+                                   aDirtyRect);
+
+    // The destRect x and y have not been set yet. Let's do that now.
+    // Initially, we use the imageRect x and y.
+    destRect.x = imageRect.x;
+    destRect.y = imageRect.y;
+
+    if (destRect.width < imageRect.width) {
+      // The destRect width is smaller than the cell width.
+      // Center the image horizontally in the cell.
+      // Adjust the destRect x accordingly.
+      destRect.x += (imageRect.width - destRect.width)/2;
+    }
+
+    // Now it's time to adjust the destRect height to fit within the cell height.
+    if (destRect.height > imageRect.height) {
+      // The destRect height is larger than the cell height.
+      // Adjust destRect height to fit within the cell height.
+      destRect.height = imageRect.height;
+    }
+    else if (destRect.height < imageRect.height) {
+      // The destRect height is smaller than the cell height.
+      // Center the image vertically in the cell.
+      // Adjust the destRect y accordingly.
+      destRect.y += (imageRect.height - destRect.height)/2;
+    }
+
+    // It's almost time to paint the image.
+    // Deflate destRect for the border and padding.
+    destRect.Deflate(bp);
+
+    // Compute the area where our whole image would be mapped, to get the
+    // desired subregion onto our actual destRect:
+    nsRect wholeImageDest;
+    CSSIntSize rawImageCSSIntSize;
+    if (NS_SUCCEEDED(image->GetWidth(&rawImageCSSIntSize.width)) &&
+        NS_SUCCEEDED(image->GetHeight(&rawImageCSSIntSize.height))) {
+      // Get the image source rectangle - the rectangle containing the part of
+      // the image that we are going to display.  sourceRect will be passed as
+      // the aSrcRect argument in the DrawImage method.
+      nsRect sourceRect = GetImageSourceRect(imageContext, useImageRegion, image);
+
+      // Let's say that the image is 100 pixels tall and that the CSS has
+      // specified that the destination height should be 50 pixels tall. Let's
+      // say that the cell height is only 20 pixels. So, in those 20 visible
+      // pixels, we want to see the top 20/50ths of the image.  So, the
+      // sourceRect.height should be 100 * 20 / 50, which is 40 pixels.
+      // Essentially, we are scaling the image as dictated by the CSS
+      // destination height and width, and we are then clipping the scaled
+      // image by the cell width and height.
+      nsSize rawImageSize(CSSPixel::ToAppUnits(rawImageCSSIntSize));
+      wholeImageDest =
+        nsLayoutUtils::GetWholeImageDestination(rawImageSize, sourceRect,
+                                                nsRect(destRect.TopLeft(),
+                                                       imageDestSize));
+    } else {
+      // GetWidth/GetHeight failed, so we can't easily map a subregion of the
+      // source image onto the destination area.
+      // * If this happens with a RasterImage, it probably means the image is
+      // in an error state, and we shouldn't draw anything. Hence, we leave
+      // wholeImageDest as an empty rect (its initial state).
+      // * If this happens with a VectorImage, it probably means the image has
+      // no explicit width or height attribute -- but we can still proceed and
+      // just treat the destination area as our whole SVG image area. Hence, we
+      // set wholeImageDest to the full destRect.
+      if (image->GetType() == imgIContainer::TYPE_VECTOR) {
+        wholeImageDest = destRect;
+      }
+    }
+
+    gfxContext* ctx = aRenderingContext.ThebesContext();
+    if (opacity != 1.0f) {
+      ctx->PushGroupForBlendBack(gfxContentType::COLOR_ALPHA, opacity);
+    }
+
+    result &=
+      nsLayoutUtils::DrawImage(*ctx, aPresContext, image,
+        nsLayoutUtils::GetSamplingFilterForFrame(this),
+        wholeImageDest, destRect, destRect.TopLeft(), aDirtyRect,
+        imgIContainer::FLAG_NONE);
+
+    if (opacity != 1.0f) {
+      ctx->PopGroupAndBlend();
+    }
+  }
+
+  // Update the aRemainingWidth and aCurrX values.
+  imageRect.Inflate(imageMargin);
+  aRemainingWidth -= imageRect.width;
+  if (!isRTL) {
+    aCurrX += imageRect.width;
+  }
+
+  return result;
+}
+
+// Disable PGO for PaintText because MSVC 2015 seems to have decided
+// that it can null out the alreadyAddRefed<nsFontMetrics> used to
+// initialize fontMet after storing fontMet on the stack in the same
+// space, overwriting fontMet's stack storage with null.
+#ifdef _MSC_VER
+# pragma optimize("g", off)
+#endif
+DrawResult
+nsTreeBodyFrame::PaintText(int32_t              aRowIndex,
+                           nsTreeColumn*        aColumn,
+                           const nsRect&        aTextRect,
+                           nsPresContext*      aPresContext,
+                           nsRenderingContext& aRenderingContext,
+                           const nsRect&        aDirtyRect,
+                           nscoord&             aCurrX)
+{
+  NS_PRECONDITION(aColumn && aColumn->GetFrame(), "invalid column passed");
+
+  bool isRTL = StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
+
+  // Now obtain the text for our cell.
+  nsAutoString text;
+  mView->GetCellText(aRowIndex, aColumn, text);
+
+  if (aColumn->Type() == nsITreeColumn::TYPE_PASSWORD) {
+    TextEditRules::FillBufWithPWChars(&text, text.Length());
+  }
+
+  // We're going to paint this text so we need to ensure bidi is enabled if
+  // necessary
+  CheckTextForBidi(text);
+
+  DrawResult result = DrawResult::SUCCESS;
+
+  if (text.Length() == 0) {
+    // Don't paint an empty string. XXX What about background/borders? Still paint?
+    return result;
+  }
+
+  int32_t appUnitsPerDevPixel = PresContext()->AppUnitsPerDevPixel();
+  DrawTarget* drawTarget = aRenderingContext.GetDrawTarget();
+
+  // Resolve style for the text.  It contains all the info we need to lay ourselves
+  // out and to paint.
+  nsStyleContext* textContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecelltext);
+
+  // Obtain opacity value for the image.
+  float opacity = textContext->StyleEffects()->mOpacity;
+
+  // Obtain the margins for the text and then deflate our rect by that 
+  // amount.  The text is assumed to be contained within the deflated rect.
+  nsRect textRect(aTextRect);
+  nsMargin textMargin;
+  textContext->StyleMargin()->GetMargin(textMargin);
+  textRect.Deflate(textMargin);
+
+  // Adjust the rect for its border and padding.
+  nsMargin bp(0,0,0,0);
+  GetBorderPadding(textContext, bp);
+  textRect.Deflate(bp);
+
+  // Compute our text size.
+  RefPtr<nsFontMetrics> fontMet =
+    nsLayoutUtils::GetFontMetricsForStyleContext(textContext);
+
+  nscoord height = fontMet->MaxHeight();
+  nscoord baseline = fontMet->MaxAscent();
+
+  // Center the text. XXX Obey vertical-align style prop?
+  if (height < textRect.height) {
+    textRect.y += (textRect.height - height)/2;
+    textRect.height = height;
+  }
+
+  // Set our font.
+  AdjustForCellText(text, aRowIndex, aColumn, aRenderingContext, *fontMet, textRect);
+  textRect.Inflate(bp);
+
+  // Subtract out the remaining width.
+  if (!isRTL)
+    aCurrX += textRect.width + textMargin.LeftRight();
+
+  result &= PaintBackgroundLayer(textContext, aPresContext, aRenderingContext,
+                                 textRect, aDirtyRect);
+
+  // Time to paint our text.
+  textRect.Deflate(bp);
+
+  // Set our color.
+  ColorPattern color(ToDeviceColor(textContext->StyleColor()->mColor));
+
+  // Draw decorations.
+  uint8_t decorations = textContext->StyleTextReset()->mTextDecorationLine;
+
+  nscoord offset;
+  nscoord size;
+  if (decorations & (NS_STYLE_TEXT_DECORATION_LINE_OVERLINE |
+                     NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE)) {
+    fontMet->GetUnderline(offset, size);
+    if (decorations & NS_STYLE_TEXT_DECORATION_LINE_OVERLINE) {
+      nsRect r(textRect.x, textRect.y, textRect.width, size);
+      Rect devPxRect =
+        NSRectToSnappedRect(r, appUnitsPerDevPixel, *drawTarget);
+      drawTarget->FillRect(devPxRect, color);
+    }
+    if (decorations & NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE) {
+      nsRect r(textRect.x, textRect.y + baseline - offset,
+               textRect.width, size);
+      Rect devPxRect =
+        NSRectToSnappedRect(r, appUnitsPerDevPixel, *drawTarget);
+      drawTarget->FillRect(devPxRect, color);
+    }
+  }
+  if (decorations & NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH) {
+    fontMet->GetStrikeout(offset, size);
+    nsRect r(textRect.x, textRect.y + baseline - offset, textRect.width, size);
+    Rect devPxRect =
+      NSRectToSnappedRect(r, appUnitsPerDevPixel, *drawTarget);
+    drawTarget->FillRect(devPxRect, color);
+  }
+  nsStyleContext* cellContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecell);
+
+  gfxContext* ctx = aRenderingContext.ThebesContext();
+  if (opacity != 1.0f) {
+    ctx->PushGroupForBlendBack(gfxContentType::COLOR_ALPHA, opacity);
+  }
+
+  ctx->SetColor(Color::FromABGR(textContext->StyleColor()->mColor));
+  nsLayoutUtils::DrawString(this, *fontMet, &aRenderingContext, text.get(),
+                            text.Length(),
+                            textRect.TopLeft() + nsPoint(0, baseline),
+                            cellContext);
+
+  if (opacity != 1.0f) {
+    ctx->PopGroupAndBlend();
+  }
+
+  return result;
+}
+#ifdef _MSC_VER
+# pragma optimize("", on)
+#endif
+
+DrawResult
+nsTreeBodyFrame::PaintCheckbox(int32_t              aRowIndex,
+                               nsTreeColumn*        aColumn,
+                               const nsRect&        aCheckboxRect,
+                               nsPresContext*      aPresContext,
+                               nsRenderingContext& aRenderingContext,
+                               const nsRect&        aDirtyRect)
+{
+  NS_PRECONDITION(aColumn && aColumn->GetFrame(), "invalid column passed");
+
+  // Resolve style for the checkbox.
+  nsStyleContext* checkboxContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreecheckbox);
+
+  nscoord rightEdge = aCheckboxRect.XMost();
+
+  // Obtain the margins for the checkbox and then deflate our rect by that 
+  // amount.  The checkbox is assumed to be contained within the deflated rect.
+  nsRect checkboxRect(aCheckboxRect);
+  nsMargin checkboxMargin;
+  checkboxContext->StyleMargin()->GetMargin(checkboxMargin);
+  checkboxRect.Deflate(checkboxMargin);
+  
+  nsRect imageSize = GetImageSize(aRowIndex, aColumn, true, checkboxContext);
+
+  if (imageSize.height > checkboxRect.height)
+    imageSize.height = checkboxRect.height;
+  if (imageSize.width > checkboxRect.width)
+    imageSize.width = checkboxRect.width;
+
+  if (StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL)
+    checkboxRect.x = rightEdge - checkboxRect.width;
+
+  // Paint our borders and background for our image rect.
+  DrawResult result = PaintBackgroundLayer(checkboxContext, aPresContext,
+                                           aRenderingContext, checkboxRect,
+                                           aDirtyRect);
+
+  // Time to paint the checkbox.
+  // Adjust the rect for its border and padding.
+  nsMargin bp(0,0,0,0);
+  GetBorderPadding(checkboxContext, bp);
+  checkboxRect.Deflate(bp);
+
+  // Get the image for drawing.
+  nsCOMPtr<imgIContainer> image;
+  bool useImageRegion = true;
+  GetImage(aRowIndex, aColumn, true, checkboxContext, useImageRegion, getter_AddRefs(image));
+  if (image) {
+    nsPoint pt = checkboxRect.TopLeft();
+          
+    if (imageSize.height < checkboxRect.height) {
+      pt.y += (checkboxRect.height - imageSize.height)/2;
+    }
+
+    if (imageSize.width < checkboxRect.width) {
+      pt.x += (checkboxRect.width - imageSize.width)/2;
+    }
+
+    // Paint the image.
+    result &=
+      nsLayoutUtils::DrawSingleUnscaledImage(*aRenderingContext.ThebesContext(),
+        aPresContext,
+        image, SamplingFilter::POINT, pt, &aDirtyRect,
+        imgIContainer::FLAG_NONE, &imageSize);
+  }
+
+  return result;
+}
+
+DrawResult
+nsTreeBodyFrame::PaintProgressMeter(int32_t              aRowIndex,
+                                    nsTreeColumn*        aColumn,
+                                    const nsRect&        aProgressMeterRect,
+                                    nsPresContext*      aPresContext,
+                                    nsRenderingContext& aRenderingContext,
+                                    const nsRect&        aDirtyRect)
+{
+  NS_PRECONDITION(aColumn && aColumn->GetFrame(), "invalid column passed");
+
+  // Resolve style for the progress meter.  It contains all the info we need
+  // to lay ourselves out and to paint.
+  nsStyleContext* meterContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreeprogressmeter);
+
+  // Obtain the margins for the progress meter and then deflate our rect by that 
+  // amount. The progress meter is assumed to be contained within the deflated
+  // rect.
+  nsRect meterRect(aProgressMeterRect);
+  nsMargin meterMargin;
+  meterContext->StyleMargin()->GetMargin(meterMargin);
+  meterRect.Deflate(meterMargin);
+
+  // Paint our borders and background for our progress meter rect.
+  DrawResult result = PaintBackgroundLayer(meterContext, aPresContext,
+                                           aRenderingContext, meterRect,
+                                           aDirtyRect);
+
+  // Time to paint our progress. 
+  int32_t state;
+  mView->GetProgressMode(aRowIndex, aColumn, &state);
+  if (state == nsITreeView::PROGRESS_NORMAL) {
+    // Adjust the rect for its border and padding.
+    AdjustForBorderPadding(meterContext, meterRect);
+
+    // Now obtain the value for our cell.
+    nsAutoString value;
+    mView->GetCellValue(aRowIndex, aColumn, value);
+
+    nsresult rv;
+    int32_t intValue = value.ToInteger(&rv);
+    if (intValue < 0)
+      intValue = 0;
+    else if (intValue > 100)
+      intValue = 100;
+
+    nscoord meterWidth = NSToCoordRound((float)intValue / 100 * meterRect.width);
+    if (StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL)
+      meterRect.x += meterRect.width - meterWidth; // right align
+    meterRect.width = meterWidth;
+    bool useImageRegion = true;
+    nsCOMPtr<imgIContainer> image;
+    GetImage(aRowIndex, aColumn, true, meterContext, useImageRegion, getter_AddRefs(image));
+    if (image) {
+      int32_t width, height;
+      image->GetWidth(&width);
+      image->GetHeight(&height);
+      nsSize size(width*nsDeviceContext::AppUnitsPerCSSPixel(),
+                  height*nsDeviceContext::AppUnitsPerCSSPixel());
+      result &=
+        nsLayoutUtils::DrawImage(*aRenderingContext.ThebesContext(),
+          aPresContext, image,
+          nsLayoutUtils::GetSamplingFilterForFrame(this),
+          nsRect(meterRect.TopLeft(), size), meterRect, meterRect.TopLeft(),
+          aDirtyRect, imgIContainer::FLAG_NONE);
+    } else {
+      DrawTarget* drawTarget = aRenderingContext.GetDrawTarget();
+      int32_t appUnitsPerDevPixel = PresContext()->AppUnitsPerDevPixel();
+      Rect rect =
+        NSRectToSnappedRect(meterRect, appUnitsPerDevPixel, *drawTarget);
+      ColorPattern color(ToDeviceColor(meterContext->StyleColor()->mColor));
+      drawTarget->FillRect(rect, color);
+    }
+  }
+  else if (state == nsITreeView::PROGRESS_UNDETERMINED) {
+    // Adjust the rect for its border and padding.
+    AdjustForBorderPadding(meterContext, meterRect);
+
+    bool useImageRegion = true;
+    nsCOMPtr<imgIContainer> image;
+    GetImage(aRowIndex, aColumn, true, meterContext, useImageRegion, getter_AddRefs(image));
+    if (image) {
+      int32_t width, height;
+      image->GetWidth(&width);
+      image->GetHeight(&height);
+      nsSize size(width*nsDeviceContext::AppUnitsPerCSSPixel(),
+                  height*nsDeviceContext::AppUnitsPerCSSPixel());
+      result &=
+        nsLayoutUtils::DrawImage(*aRenderingContext.ThebesContext(),
+          aPresContext, image,
+          nsLayoutUtils::GetSamplingFilterForFrame(this),
+          nsRect(meterRect.TopLeft(), size), meterRect, meterRect.TopLeft(),
+          aDirtyRect, imgIContainer::FLAG_NONE);
+    }
+  }
+
+  return result;
+}
+
+
+DrawResult
+nsTreeBodyFrame::PaintDropFeedback(const nsRect&        aDropFeedbackRect,
+                                   nsPresContext*      aPresContext,
+                                   nsRenderingContext& aRenderingContext,
+                                   const nsRect&        aDirtyRect,
+                                   nsPoint              aPt)
+{
+  // Paint the drop feedback in between rows.
+
+  nscoord currX;
+
+  // Adjust for the primary cell.
+  nsTreeColumn* primaryCol = mColumns->GetPrimaryColumn();
+
+  if (primaryCol) {
+#ifdef DEBUG
+    nsresult rv =
+#endif
+      primaryCol->GetXInTwips(this, &currX);
+    NS_ASSERTION(NS_SUCCEEDED(rv), "primary column is invalid?");
+
+    currX += aPt.x - mHorzPosition;
+  } else {
+    currX = aDropFeedbackRect.x;
+  }
+
+  PrefillPropertyArray(mSlots->mDropRow, primaryCol);
+
+  // Resolve the style to use for the drop feedback.
+  nsStyleContext* feedbackContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreedropfeedback);
+
+  DrawResult result = DrawResult::SUCCESS;
+
+  // Paint only if it is visible.
+  if (feedbackContext->StyleVisibility()->IsVisibleOrCollapsed()) {
+    int32_t level;
+    mView->GetLevel(mSlots->mDropRow, &level);
+
+    // If our previous or next row has greater level use that for 
+    // correct visual indentation.
+    if (mSlots->mDropOrient == nsITreeView::DROP_BEFORE) {
+      if (mSlots->mDropRow > 0) {
+        int32_t previousLevel;
+        mView->GetLevel(mSlots->mDropRow - 1, &previousLevel);
+        if (previousLevel > level)
+          level = previousLevel;
+      }
+    }
+    else {
+      if (mSlots->mDropRow < mRowCount - 1) {
+        int32_t nextLevel;
+        mView->GetLevel(mSlots->mDropRow + 1, &nextLevel);
+        if (nextLevel > level)
+          level = nextLevel;
+      }
+    }
+
+    currX += mIndentation * level;
+
+    if (primaryCol){
+      nsStyleContext* twistyContext = GetPseudoStyleContext(nsCSSAnonBoxes::moztreetwisty);
+      nsRect imageSize;
+      nsRect twistyRect;
+      GetTwistyRect(mSlots->mDropRow, primaryCol, imageSize, twistyRect,
+                    aPresContext, twistyContext);
+      nsMargin twistyMargin;
+      twistyContext->StyleMargin()->GetMargin(twistyMargin);
+      twistyRect.Inflate(twistyMargin);
+      currX += twistyRect.width;
+    }
+
+    const nsStylePosition* stylePosition = feedbackContext->StylePosition();
+
+    // Obtain the width for the drop feedback or use default value.
+    nscoord width;
+    if (stylePosition->mWidth.GetUnit() == eStyleUnit_Coord)
+      width = stylePosition->mWidth.GetCoordValue();
+    else {
+      // Use default width 50px.
+      width = nsPresContext::CSSPixelsToAppUnits(50);
+    }
+
+    // Obtain the height for the drop feedback or use default value.
+    nscoord height;
+    if (stylePosition->mHeight.GetUnit() == eStyleUnit_Coord)
+      height = stylePosition->mHeight.GetCoordValue();
+    else {
+      // Use default height 2px.
+      height = nsPresContext::CSSPixelsToAppUnits(2);
+    }
+
+    // Obtain the margins for the drop feedback and then deflate our rect
+    // by that amount.
+    nsRect feedbackRect(currX, aDropFeedbackRect.y, width, height);
+    nsMargin margin;
+    feedbackContext->StyleMargin()->GetMargin(margin);
+    feedbackRect.Deflate(margin);
+
+    feedbackRect.y += (aDropFeedbackRect.height - height) / 2;
+
+    // Finally paint the drop feedback.
+    result &= PaintBackgroundLayer(feedbackContext, aPresContext,
+                                   aRenderingContext, feedbackRect,
+                                   aDirtyRect);
+  }
+
+  return result;
+}
+
+DrawResult
+nsTreeBodyFrame::PaintBackgroundLayer(nsStyleContext*      aStyleContext,
+                                      nsPresContext*      aPresContext,
+                                      nsRenderingContext& aRenderingContext,
+                                      const nsRect&        aRect,
+                                      const nsRect&        aDirtyRect)
+{
+  const nsStyleBorder* myBorder = aStyleContext->StyleBorder();
+  nsCSSRendering::PaintBGParams params =
+    nsCSSRendering::PaintBGParams::ForAllLayers(*aPresContext, aRenderingContext,
+                                                aDirtyRect, aRect, this,
+                                                nsCSSRendering::PAINTBG_SYNC_DECODE_IMAGES);
+  DrawResult result =
+    nsCSSRendering::PaintBackgroundWithSC(params, aStyleContext, *myBorder);
+
+  result &=
+    nsCSSRendering::PaintBorderWithStyleBorder(aPresContext, aRenderingContext,
+                                               this, aDirtyRect, aRect,
+                                               *myBorder, mStyleContext,
+                                               PaintBorderFlags::SYNC_DECODE_IMAGES);
+
+  nsCSSRendering::PaintOutline(aPresContext, aRenderingContext, this,
+                               aDirtyRect, aRect, aStyleContext);
+
+  return result;
+}
+
+// Scrolling
+nsresult
+nsTreeBodyFrame::EnsureRowIsVisible(int32_t aRow)
+{
+  ScrollParts parts = GetScrollParts();
+  nsresult rv = EnsureRowIsVisibleInternal(parts, aRow);
+  NS_ENSURE_SUCCESS(rv, rv);
+  UpdateScrollbars(parts);
+  return rv;
+}
+
+nsresult nsTreeBodyFrame::EnsureRowIsVisibleInternal(const ScrollParts& aParts, int32_t aRow)
+{
+  if (!mView || !mPageLength)
+    return NS_OK;
+
+  if (mTopRowIndex <= aRow && mTopRowIndex+mPageLength > aRow)
+    return NS_OK;
+
+  if (aRow < mTopRowIndex)
+    ScrollToRowInternal(aParts, aRow);
+  else {
+    // Bring it just on-screen.
+    int32_t distance = aRow - (mTopRowIndex+mPageLength)+1;
+    ScrollToRowInternal(aParts, mTopRowIndex+distance);
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::EnsureCellIsVisible(int32_t aRow, nsITreeColumn* aCol)
+{
+  RefPtr<nsTreeColumn> col = GetColumnImpl(aCol);
+  if (!col)
+    return NS_ERROR_INVALID_ARG;
+
+  ScrollParts parts = GetScrollParts();
+
+  nscoord result = -1;
+  nsresult rv;
+
+  nscoord columnPos;
+  rv = col->GetXInTwips(this, &columnPos);
+  if(NS_FAILED(rv)) return rv;
+
+  nscoord columnWidth;
+  rv = col->GetWidthInTwips(this, &columnWidth);
+  if(NS_FAILED(rv)) return rv;
+
+  // If the start of the column is before the
+  // start of the horizontal view, then scroll
+  if (columnPos < mHorzPosition)
+    result = columnPos;
+  // If the end of the column is past the end of 
+  // the horizontal view, then scroll
+  else if ((columnPos + columnWidth) > (mHorzPosition + mInnerBox.width))
+    result = ((columnPos + columnWidth) - (mHorzPosition + mInnerBox.width)) + mHorzPosition;
+
+  if (result != -1) {
+    rv = ScrollHorzInternal(parts, result);
+    if(NS_FAILED(rv)) return rv;
+  }
+
+  rv = EnsureRowIsVisibleInternal(parts, aRow);
+  NS_ENSURE_SUCCESS(rv, rv);
+  UpdateScrollbars(parts);
+  return rv;
+}
+
+nsresult
+nsTreeBodyFrame::ScrollToCell(int32_t aRow, nsITreeColumn* aCol)
+{
+  ScrollParts parts = GetScrollParts();
+  nsresult rv = ScrollToRowInternal(parts, aRow);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = ScrollToColumnInternal(parts, aCol);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  UpdateScrollbars(parts);
+  return rv;
+}
+
+nsresult
+nsTreeBodyFrame::ScrollToColumn(nsITreeColumn* aCol)
+{
+  ScrollParts parts = GetScrollParts();
+  nsresult rv = ScrollToColumnInternal(parts, aCol);
+  NS_ENSURE_SUCCESS(rv, rv);
+  UpdateScrollbars(parts);
+  return rv;
+}
+
+nsresult nsTreeBodyFrame::ScrollToColumnInternal(const ScrollParts& aParts,
+                                                 nsITreeColumn* aCol)
+{
+  RefPtr<nsTreeColumn> col = GetColumnImpl(aCol);
+  if (!col)
+    return NS_ERROR_INVALID_ARG;
+
+  nscoord x;
+  nsresult rv = col->GetXInTwips(this, &x);
+  if (NS_FAILED(rv))
+    return rv;
+
+  return ScrollHorzInternal(aParts, x);
+}
+
+nsresult
+nsTreeBodyFrame::ScrollToHorizontalPosition(int32_t aHorizontalPosition)
+{
+  ScrollParts parts = GetScrollParts();
+  int32_t position = nsPresContext::CSSPixelsToAppUnits(aHorizontalPosition);
+  nsresult rv = ScrollHorzInternal(parts, position);
+  NS_ENSURE_SUCCESS(rv, rv);
+  UpdateScrollbars(parts);
+  return rv;
+}
+
+nsresult
+nsTreeBodyFrame::ScrollToRow(int32_t aRow)
+{
+  ScrollParts parts = GetScrollParts();
+  ScrollToRowInternal(parts, aRow);
+  UpdateScrollbars(parts);
+  return NS_OK;
+}
+
+nsresult nsTreeBodyFrame::ScrollToRowInternal(const ScrollParts& aParts, int32_t aRow)
+{
+  ScrollInternal(aParts, aRow);
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::ScrollByLines(int32_t aNumLines)
+{
+  if (!mView) {
+    return NS_OK;
+  }
+  int32_t newIndex = mTopRowIndex + aNumLines;
+  ScrollToRow(newIndex);
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::ScrollByPages(int32_t aNumPages)
+{
+  if (!mView) {
+    return NS_OK;
+  }
+  int32_t newIndex = mTopRowIndex + aNumPages * mPageLength;
+  ScrollToRow(newIndex);
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::ScrollInternal(const ScrollParts& aParts, int32_t aRow)
+{
+  if (!mView) {
+    return NS_OK;
+  }
+
+  // Note that we may be "over scrolled" at this point; that is the
+  // current mTopRowIndex may be larger than mRowCount - mPageLength.
+  // This can happen when items are removed for example. (bug 1085050)
+
+  int32_t maxTopRowIndex = std::max(0, mRowCount - mPageLength);
+  aRow = mozilla::clamped(aRow, 0, maxTopRowIndex);
+  if (aRow == mTopRowIndex) {
+    return NS_OK;
+  }
+  mTopRowIndex = aRow;
+  Invalidate();
+  PostScrollEvent();
+  return NS_OK;
+}
+
+nsresult
+nsTreeBodyFrame::ScrollHorzInternal(const ScrollParts& aParts, int32_t aPosition)
+{
+  if (!mView || !aParts.mColumnsScrollFrame || !aParts.mHScrollbar)
+    return NS_OK;
+
+  if (aPosition == mHorzPosition)
+    return NS_OK;
+
+  if (aPosition < 0 || aPosition > mHorzWidth)
+    return NS_OK;
+
+  nsRect bounds = aParts.mColumnsFrame->GetRect();
+  if (aPosition > (mHorzWidth - bounds.width)) 
+    aPosition = mHorzWidth - bounds.width;
+
+  mHorzPosition = aPosition;
+
+  Invalidate();
+
+  // Update the column scroll view
+  nsWeakFrame weakFrame(this);
+  aParts.mColumnsScrollFrame->ScrollTo(nsPoint(mHorzPosition, 0),
+                                       nsIScrollableFrame::INSTANT);
+  if (!weakFrame.IsAlive()) {
+    return NS_ERROR_FAILURE;
+  }
+  // And fire off an event about it all
+  PostScrollEvent();
+  return NS_OK;
+}
+
+void
+nsTreeBodyFrame::ScrollByPage(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                              nsIScrollbarMediator::ScrollSnapMode aSnap)
+{
+  // CSS Scroll Snapping is not enabled for XUL, aSnap is ignored
+  MOZ_ASSERT(aScrollbar != nullptr);
+  ScrollByPages(aDirection);
+}
+
+void
+nsTreeBodyFrame::ScrollByWhole(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                               nsIScrollbarMediator::ScrollSnapMode aSnap)
+{
+  // CSS Scroll Snapping is not enabled for XUL, aSnap is ignored
+  MOZ_ASSERT(aScrollbar != nullptr); 
+  int32_t newIndex = aDirection < 0 ? 0 : mTopRowIndex;
+  ScrollToRow(newIndex);
+}
+
+void
+nsTreeBodyFrame::ScrollByLine(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                              nsIScrollbarMediator::ScrollSnapMode aSnap)
+{
+  // CSS Scroll Snapping is not enabled for XUL, aSnap is ignored
+  MOZ_ASSERT(aScrollbar != nullptr);
+  ScrollByLines(aDirection);
+}
+
+void
+nsTreeBodyFrame::RepeatButtonScroll(nsScrollbarFrame* aScrollbar)
+{
+  ScrollParts parts = GetScrollParts();
+  int32_t increment = aScrollbar->GetIncrement();
+  int32_t direction = 0;
+  if (increment < 0) {
+    direction = -1;
+  } else if (increment > 0) {
+    direction = 1;
+  }
+  bool isHorizontal = aScrollbar->IsXULHorizontal();
+
+  nsWeakFrame weakFrame(this);
+  if (isHorizontal) {
+    int32_t curpos = aScrollbar->MoveToNewPosition();
+    if (weakFrame.IsAlive()) {
+      ScrollHorzInternal(parts, curpos);
+    }
+  } else {
+    ScrollToRowInternal(parts, mTopRowIndex+direction);
+  }
+
+  if (weakFrame.IsAlive() && mScrollbarActivity) {
+    mScrollbarActivity->ActivityOccurred();
+  }
+  if (weakFrame.IsAlive()) {
+    UpdateScrollbars(parts);
+  }
+}
+
+void
+nsTreeBodyFrame::ThumbMoved(nsScrollbarFrame* aScrollbar,
+                            nscoord aOldPos,
+                            nscoord aNewPos)
+{
+  ScrollParts parts = GetScrollParts();
+  
+  if (aOldPos == aNewPos)
+    return;
+
+  nsWeakFrame weakFrame(this);
+
+  // Vertical Scrollbar 
+  if (parts.mVScrollbar == aScrollbar) {
+    nscoord rh = nsPresContext::AppUnitsToIntCSSPixels(mRowHeight);
+    nscoord newIndex = nsPresContext::AppUnitsToIntCSSPixels(aNewPos);
+    nscoord newrow = newIndex/rh;
+    ScrollInternal(parts, newrow);
+  // Horizontal Scrollbar
+  } else if (parts.mHScrollbar == aScrollbar) {
+    int32_t newIndex = nsPresContext::AppUnitsToIntCSSPixels(aNewPos);
+    ScrollHorzInternal(parts, newIndex);
+  }
+  if (weakFrame.IsAlive()) {
+    UpdateScrollbars(parts);
+  }
+}
+
+// The style cache.
+nsStyleContext*
+nsTreeBodyFrame::GetPseudoStyleContext(nsIAtom* aPseudoElement)
+{
+  return mStyleCache.GetStyleContext(this, PresContext(), mContent,
+                                     mStyleContext, aPseudoElement,
+                                     mScratchArray);
+}
+
+// Our comparator for resolving our complex pseudos
+bool
+nsTreeBodyFrame::PseudoMatches(nsCSSSelector* aSelector)
+{
+  // Iterate the class list.  For each item in the list, see if
+  // it is contained in our scratch array.  If we have a miss, then
+  // we aren't a match.  If all items in the class list are
+  // present in the scratch array, then we have a match.
+  nsAtomList* curr = aSelector->mClassList;
+  while (curr) {
+    if (!mScratchArray.Contains(curr->mAtom))
+      return false;
+    curr = curr->mNext;
+  }
+  return true;
+}
+
+nsIContent*
+nsTreeBodyFrame::GetBaseElement()
+{
+  nsIFrame* parent = GetParent();
+  while (parent) {
+    nsIContent* content = parent->GetContent();
+    if (content) {
+      dom::NodeInfo* ni = content->NodeInfo();
+
+      if (ni->Equals(nsGkAtoms::tree, kNameSpaceID_XUL) ||
+          (ni->Equals(nsGkAtoms::select) &&
+           content->IsHTMLElement()))
+        return content;
+    }
+
+    parent = parent->GetParent();
+  }
+
+  return nullptr;
+}
+
+nsresult
+nsTreeBodyFrame::ClearStyleAndImageCaches()
+{
+  mStyleCache.Clear();
+  CancelImageRequests();
+  mImageCache.Clear();
+  return NS_OK;
+}
+
+/* virtual */ void
+nsTreeBodyFrame::DidSetStyleContext(nsStyleContext* aOldStyleContext)
+{
+  nsLeafBoxFrame::DidSetStyleContext(aOldStyleContext);
+
+  // Clear the style cache; the pointers are no longer even valid
+  mStyleCache.Clear();
+  // XXX The following is hacky, but it's not incorrect,
+  // and appears to fix a few bugs with style changes, like text zoom and
+  // dpi changes
+  mIndentation = GetIndentation();
+  mRowHeight = GetRowHeight();
+  mStringWidth = -1;
+}
+
+bool 
+nsTreeBodyFrame::OffsetForHorzScroll(nsRect& rect, bool clip)
+{
+  rect.x -= mHorzPosition;
+
+  // Scrolled out before
+  if (rect.XMost() <= mInnerBox.x)
+    return false;
+
+  // Scrolled out after
+  if (rect.x > mInnerBox.XMost())
+    return false;
+
+  if (clip) {
+    nscoord leftEdge = std::max(rect.x, mInnerBox.x);
+    nscoord rightEdge = std::min(rect.XMost(), mInnerBox.XMost());
+    rect.x = leftEdge;
+    rect.width = rightEdge - leftEdge;
+
+    // Should have returned false above
+    NS_ASSERTION(rect.width >= 0, "horz scroll code out of sync");
+  }
+
+  return true;
+}
+
+bool
+nsTreeBodyFrame::CanAutoScroll(int32_t aRowIndex)
+{
+  // Check first for partially visible last row.
+  if (aRowIndex == mRowCount - 1) {
+    nscoord y = mInnerBox.y + (aRowIndex - mTopRowIndex) * mRowHeight;
+    if (y < mInnerBox.height && y + mRowHeight > mInnerBox.height)
+      return true;
+  }
+
+  if (aRowIndex > 0 && aRowIndex < mRowCount - 1)
+    return true;
+
+  return false;
+}
+
+// Given a dom event, figure out which row in the tree the mouse is over,
+// if we should drop before/after/on that row or we should auto-scroll.
+// Doesn't query the content about if the drag is allowable, that's done elsewhere.
+//
+// For containers, we break up the vertical space of the row as follows: if in
+// the topmost 25%, the drop is _before_ the row the mouse is over; if in the
+// last 25%, _after_; in the middle 50%, we consider it a drop _on_ the container.
+//
+// For non-containers, if the mouse is in the top 50% of the row, the drop is
+// _before_ and the bottom 50% _after_
+void 
+nsTreeBodyFrame::ComputeDropPosition(WidgetGUIEvent* aEvent,
+                                     int32_t* aRow,
+                                     int16_t* aOrient,
+                                     int16_t* aScrollLines)
+{
+  *aOrient = -1;
+  *aScrollLines = 0;
+
+  // Convert the event's point to our coordinates.  We want it in
+  // the coordinates of our inner box's coordinates.
+  nsPoint pt = nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, this);
+  int32_t xTwips = pt.x - mInnerBox.x;
+  int32_t yTwips = pt.y - mInnerBox.y;
+
+  *aRow = GetRowAt(xTwips, yTwips);
+  if (*aRow >=0) {
+    // Compute the top/bottom of the row in question.
+    int32_t yOffset = yTwips - mRowHeight * (*aRow - mTopRowIndex);
+   
+    bool isContainer = false;
+    mView->IsContainer (*aRow, &isContainer);
+    if (isContainer) {
+      // for a container, use a 25%/50%/25% breakdown
+      if (yOffset < mRowHeight / 4)
+        *aOrient = nsITreeView::DROP_BEFORE;
+      else if (yOffset > mRowHeight - (mRowHeight / 4))
+        *aOrient = nsITreeView::DROP_AFTER;
+      else
+        *aOrient = nsITreeView::DROP_ON;
+    }
+    else {
+      // for a non-container use a 50%/50% breakdown
+      if (yOffset < mRowHeight / 2)
+        *aOrient = nsITreeView::DROP_BEFORE;
+      else
+        *aOrient = nsITreeView::DROP_AFTER;
+    }
+  }
+
+  if (CanAutoScroll(*aRow)) {
+    // Get the max value from the look and feel service.
+    int32_t scrollLinesMax =
+      LookAndFeel::GetInt(LookAndFeel::eIntID_TreeScrollLinesMax, 0);
+    scrollLinesMax--;
+    if (scrollLinesMax < 0)
+      scrollLinesMax = 0;
+
+    // Determine if we're w/in a margin of the top/bottom of the tree during a drag.
+    // This will ultimately cause us to scroll, but that's done elsewhere.
+    nscoord height = (3 * mRowHeight) / 4;
+    if (yTwips < height) {
+      // scroll up
+      *aScrollLines = NSToIntRound(-scrollLinesMax * (1 - (float)yTwips / height) - 1);
+    }
+    else if (yTwips > mRect.height - height) {
+      // scroll down
+      *aScrollLines = NSToIntRound(scrollLinesMax * (1 - (float)(mRect.height - yTwips) / height) + 1);
+    }
+  }
+} // ComputeDropPosition
+
+void
+nsTreeBodyFrame::OpenCallback(nsITimer *aTimer, void *aClosure)
+{
+  nsTreeBodyFrame* self = static_cast<nsTreeBodyFrame*>(aClosure);
+  if (self) {
+    aTimer->Cancel();
+    self->mSlots->mTimer = nullptr;
+
+    if (self->mSlots->mDropRow >= 0) {
+      self->mSlots->mArray.AppendElement(self->mSlots->mDropRow);
+      self->mView->ToggleOpenState(self->mSlots->mDropRow);
+    }
+  }
+}
+
+void
+nsTreeBodyFrame::CloseCallback(nsITimer *aTimer, void *aClosure)
+{
+  nsTreeBodyFrame* self = static_cast<nsTreeBodyFrame*>(aClosure);
+  if (self) {
+    aTimer->Cancel();
+    self->mSlots->mTimer = nullptr;
+
+    for (uint32_t i = self->mSlots->mArray.Length(); i--; ) {
+      if (self->mView)
+        self->mView->ToggleOpenState(self->mSlots->mArray[i]);
+    }
+    self->mSlots->mArray.Clear();
+  }
+}
+
+void
+nsTreeBodyFrame::LazyScrollCallback(nsITimer *aTimer, void *aClosure)
+{
+  nsTreeBodyFrame* self = static_cast<nsTreeBodyFrame*>(aClosure);
+  if (self) {
+    aTimer->Cancel();
+    self->mSlots->mTimer = nullptr;
+
+    if (self->mView) {
+      // Set a new timer to scroll the tree repeatedly.
+      self->CreateTimer(LookAndFeel::eIntID_TreeScrollDelay,
+                        ScrollCallback, nsITimer::TYPE_REPEATING_SLACK,
+                        getter_AddRefs(self->mSlots->mTimer));
+      self->ScrollByLines(self->mSlots->mScrollLines);
+      // ScrollByLines may have deleted |self|.
+    }
+  }
+}
+
+void
+nsTreeBodyFrame::ScrollCallback(nsITimer *aTimer, void *aClosure)
+{
+  nsTreeBodyFrame* self = static_cast<nsTreeBodyFrame*>(aClosure);
+  if (self) {
+    // Don't scroll if we are already at the top or bottom of the view.
+    if (self->mView && self->CanAutoScroll(self->mSlots->mDropRow)) {
+      self->ScrollByLines(self->mSlots->mScrollLines);
+    }
+    else {
+      aTimer->Cancel();
+      self->mSlots->mTimer = nullptr;
+    }
+  }
+}
+
+NS_IMETHODIMP
+nsTreeBodyFrame::ScrollEvent::Run()
+{
+  if (mInner) {
+    mInner->FireScrollEvent();
+  }
+  return NS_OK;
+}
+
+
+void
+nsTreeBodyFrame::FireScrollEvent()
+{
+  mScrollEvent.Forget();
+  WidgetGUIEvent event(true, eScroll, nullptr);
+  // scroll events fired at elements don't bubble
+  event.mFlags.mBubbles = false;
+  EventDispatcher::Dispatch(GetContent(), PresContext(), &event);
+}
+
+void
+nsTreeBodyFrame::PostScrollEvent()
+{
+  if (mScrollEvent.IsPending())
+    return;
+
+  RefPtr<ScrollEvent> ev = new ScrollEvent(this);
+  if (NS_FAILED(NS_DispatchToCurrentThread(ev))) {
+    NS_WARNING("failed to dispatch ScrollEvent");
+  } else {
+    mScrollEvent = ev;
+  }
+}
+
+void
+nsTreeBodyFrame::ScrollbarActivityStarted() const
+{
+  if (mScrollbarActivity) {
+    mScrollbarActivity->ActivityStarted();
+  }
+}
+
+void
+nsTreeBodyFrame::ScrollbarActivityStopped() const
+{
+  if (mScrollbarActivity) {
+    mScrollbarActivity->ActivityStopped();
+  }
+}
+
+void
+nsTreeBodyFrame::DetachImageListeners()
+{
+  mCreatedListeners.Clear();
+}
+
+void
+nsTreeBodyFrame::RemoveTreeImageListener(nsTreeImageListener* aListener)
+{
+  if (aListener) {
+    mCreatedListeners.RemoveEntry(aListener);
+  }
+}
+
+#ifdef ACCESSIBILITY
+void
+nsTreeBodyFrame::FireRowCountChangedEvent(int32_t aIndex, int32_t aCount)
+{
+  nsCOMPtr<nsIContent> content(GetBaseElement());
+  if (!content)
+    return;
+
+  nsCOMPtr<nsIDOMDocument> domDoc = do_QueryInterface(content->OwnerDoc());
+  if (!domDoc)
+    return;
+
+  nsCOMPtr<nsIDOMEvent> event;
+  domDoc->CreateEvent(NS_LITERAL_STRING("customevent"),
+                      getter_AddRefs(event));
+
+  nsCOMPtr<nsIDOMCustomEvent> treeEvent(do_QueryInterface(event));
+  if (!treeEvent)
+    return;
+
+  nsCOMPtr<nsIWritablePropertyBag2> propBag(
+    do_CreateInstance("@mozilla.org/hash-property-bag;1"));
+  if (!propBag)
+    return;
+
+  // Set 'index' data - the row index rows are changed from.
+  propBag->SetPropertyAsInt32(NS_LITERAL_STRING("index"), aIndex);
+
+  // Set 'count' data - the number of changed rows.
+  propBag->SetPropertyAsInt32(NS_LITERAL_STRING("count"), aCount);
+
+  RefPtr<nsVariant> detailVariant(new nsVariant());
+
+  detailVariant->SetAsISupports(propBag);
+  treeEvent->InitCustomEvent(NS_LITERAL_STRING("TreeRowCountChanged"),
+                             true, false, detailVariant);
+
+  event->SetTrusted(true);
+
+  RefPtr<AsyncEventDispatcher> asyncDispatcher =
+    new AsyncEventDispatcher(content, event);
+  asyncDispatcher->PostDOMEvent();
+}
+
+void
+nsTreeBodyFrame::FireInvalidateEvent(int32_t aStartRowIdx, int32_t aEndRowIdx,
+                                     nsITreeColumn *aStartCol,
+                                     nsITreeColumn *aEndCol)
+{
+  nsCOMPtr<nsIContent> content(GetBaseElement());
+  if (!content)
+    return;
+
+  nsCOMPtr<nsIDOMDocument> domDoc = do_QueryInterface(content->OwnerDoc());
+  if (!domDoc)
+    return;
+
+  nsCOMPtr<nsIDOMEvent> event;
+  domDoc->CreateEvent(NS_LITERAL_STRING("customevent"),
+                      getter_AddRefs(event));
+
+  nsCOMPtr<nsIDOMCustomEvent> treeEvent(do_QueryInterface(event));
+  if (!treeEvent)
+    return;
+
+  nsCOMPtr<nsIWritablePropertyBag2> propBag(
+    do_CreateInstance("@mozilla.org/hash-property-bag;1"));
+  if (!propBag)
+    return;
+
+  if (aStartRowIdx != -1 && aEndRowIdx != -1) {
+    // Set 'startrow' data - the start index of invalidated rows.
+    propBag->SetPropertyAsInt32(NS_LITERAL_STRING("startrow"),
+                                aStartRowIdx);
+
+    // Set 'endrow' data - the end index of invalidated rows.
+    propBag->SetPropertyAsInt32(NS_LITERAL_STRING("endrow"),
+                                aEndRowIdx);
+  }
+
+  if (aStartCol && aEndCol) {
+    // Set 'startcolumn' data - the start index of invalidated rows.
+    int32_t startColIdx = 0;
+    nsresult rv = aStartCol->GetIndex(&startColIdx);
+    if (NS_FAILED(rv))
+      return;
+
+    propBag->SetPropertyAsInt32(NS_LITERAL_STRING("startcolumn"),
+                                startColIdx);
+
+    // Set 'endcolumn' data - the start index of invalidated rows.
+    int32_t endColIdx = 0;
+    rv = aEndCol->GetIndex(&endColIdx);
+    if (NS_FAILED(rv))
+      return;
+
+    propBag->SetPropertyAsInt32(NS_LITERAL_STRING("endcolumn"),
+                                endColIdx);
+  }
+
+  RefPtr<nsVariant> detailVariant(new nsVariant());
+
+  detailVariant->SetAsISupports(propBag);
+  treeEvent->InitCustomEvent(NS_LITERAL_STRING("TreeInvalidated"),
+                             true, false, detailVariant);
+
+  event->SetTrusted(true);
+
+  RefPtr<AsyncEventDispatcher> asyncDispatcher =
+    new AsyncEventDispatcher(content, event);
+  asyncDispatcher->PostDOMEvent();
+}
+#endif
+
+class nsOverflowChecker : public Runnable
+{
+public:
+  explicit nsOverflowChecker(nsTreeBodyFrame* aFrame) : mFrame(aFrame) {}
+  NS_IMETHOD Run() override
+  {
+    if (mFrame.IsAlive()) {
+      nsTreeBodyFrame* tree = static_cast<nsTreeBodyFrame*>(mFrame.GetFrame());
+      nsTreeBodyFrame::ScrollParts parts = tree->GetScrollParts();
+      tree->CheckOverflow(parts);
+    }
+    return NS_OK;
+  }
+private:
+  nsWeakFrame mFrame;
+};
+
+bool
+nsTreeBodyFrame::FullScrollbarsUpdate(bool aNeedsFullInvalidation)
+{
+  ScrollParts parts = GetScrollParts();
+  nsWeakFrame weakFrame(this);
+  nsWeakFrame weakColumnsFrame(parts.mColumnsFrame);
+  UpdateScrollbars(parts);
+  NS_ENSURE_TRUE(weakFrame.IsAlive(), false);
+  if (aNeedsFullInvalidation) {
+    Invalidate();
+  }
+  InvalidateScrollbars(parts, weakColumnsFrame);
+  NS_ENSURE_TRUE(weakFrame.IsAlive(), false);
+
+  // Overflow checking dispatches synchronous events, which can cause infinite
+  // recursion during reflow. Do the first overflow check synchronously, but
+  // force any nested checks to round-trip through the event loop. See bug
+  // 905909.
+  RefPtr<nsOverflowChecker> checker = new nsOverflowChecker(this);
+  if (!mCheckingOverflow) {
+    nsContentUtils::AddScriptRunner(checker);
+  } else {
+    NS_DispatchToCurrentThread(checker);
+  }
+  return weakFrame.IsAlive();
+}
+
+nsresult
+nsTreeBodyFrame::OnImageIsAnimated(imgIRequest* aRequest)
+{
+  nsLayoutUtils::RegisterImageRequest(PresContext(),
+                                      aRequest, nullptr);
+
+  return NS_OK;
+}
diff --git a/layout/xul/tree/nsTreeBodyFrame.h b/layout/xul/tree/nsTreeBodyFrame.h
new file mode 100644
index 0000000000..9620c8ccb3
--- /dev/null
+++ b/layout/xul/tree/nsTreeBodyFrame.h
@@ -0,0 +1,651 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTreeBodyFrame_h
+#define nsTreeBodyFrame_h
+
+#include "mozilla/Attributes.h"
+
+#include "nsLeafBoxFrame.h"
+#include "nsITreeView.h"
+#include "nsICSSPseudoComparator.h"
+#include "nsIScrollbarMediator.h"
+#include "nsITimer.h"
+#include "nsIReflowCallback.h"
+#include "nsTArray.h"
+#include "nsTreeStyleCache.h"
+#include "nsTreeColumns.h"
+#include "nsDataHashtable.h"
+#include "imgIRequest.h"
+#include "imgINotificationObserver.h"
+#include "nsScrollbarFrame.h"
+#include "nsThreadUtils.h"
+#include "mozilla/LookAndFeel.h"
+
+class nsFontMetrics;
+class nsOverflowChecker;
+class nsTreeImageListener;
+
+namespace mozilla {
+namespace layout {
+class ScrollbarActivity;
+} // namespace layout
+} // namespace mozilla
+
+// An entry in the tree's image cache
+struct nsTreeImageCacheEntry
+{
+  nsTreeImageCacheEntry() {}
+  nsTreeImageCacheEntry(imgIRequest *aRequest, imgINotificationObserver *aListener)
+    : request(aRequest), listener(aListener) {}
+
+  nsCOMPtr<imgIRequest> request;
+  nsCOMPtr<imgINotificationObserver> listener;
+};
+
+// The actual frame that paints the cells and rows.
+class nsTreeBodyFrame final
+  : public nsLeafBoxFrame
+  , public nsICSSPseudoComparator
+  , public nsIScrollbarMediator
+  , public nsIReflowCallback
+{
+  typedef mozilla::layout::ScrollbarActivity ScrollbarActivity;
+  typedef mozilla::image::DrawResult DrawResult;
+
+public:
+  explicit nsTreeBodyFrame(nsStyleContext* aContext);
+  ~nsTreeBodyFrame();
+
+  NS_DECL_QUERYFRAME_TARGET(nsTreeBodyFrame)
+  NS_DECL_QUERYFRAME
+  NS_DECL_FRAMEARENA_HELPERS
+
+  // Callback handler methods for refresh driver based animations.
+  // Calls to these functions are forwarded from nsTreeImageListener. These
+  // mirror how nsImageFrame works.
+  nsresult OnImageIsAnimated(imgIRequest* aRequest);
+
+  // non-virtual signatures like nsITreeBodyFrame
+  already_AddRefed<nsTreeColumns> Columns() const
+  {
+    RefPtr<nsTreeColumns> cols = mColumns;
+    return cols.forget();
+  }
+  already_AddRefed<nsITreeView> GetExistingView() const
+  {
+    nsCOMPtr<nsITreeView> view = mView;
+    return view.forget();
+  }
+  nsresult GetView(nsITreeView **aView);
+  nsresult SetView(nsITreeView *aView);
+  bool GetFocused() const { return mFocused; }
+  nsresult SetFocused(bool aFocused);
+  nsresult GetTreeBody(nsIDOMElement **aElement);
+  int32_t RowHeight() const;
+  int32_t RowWidth();
+  int32_t GetHorizontalPosition() const;
+  nsresult GetSelectionRegion(nsIScriptableRegion **aRegion);
+  int32_t FirstVisibleRow() const { return mTopRowIndex; }
+  int32_t LastVisibleRow() const { return mTopRowIndex + mPageLength; }
+  int32_t PageLength() const { return mPageLength; }
+  nsresult EnsureRowIsVisible(int32_t aRow);
+  nsresult EnsureCellIsVisible(int32_t aRow, nsITreeColumn *aCol);
+  nsresult ScrollToRow(int32_t aRow);
+  nsresult ScrollByLines(int32_t aNumLines);
+  nsresult ScrollByPages(int32_t aNumPages);
+  nsresult ScrollToCell(int32_t aRow, nsITreeColumn *aCol);
+  nsresult ScrollToColumn(nsITreeColumn *aCol);
+  nsresult ScrollToHorizontalPosition(int32_t aValue);
+  nsresult Invalidate();
+  nsresult InvalidateColumn(nsITreeColumn *aCol);
+  nsresult InvalidateRow(int32_t aRow);
+  nsresult InvalidateCell(int32_t aRow, nsITreeColumn *aCol);
+  nsresult InvalidateRange(int32_t aStart, int32_t aEnd);
+  nsresult InvalidateColumnRange(int32_t aStart, int32_t aEnd,
+                                 nsITreeColumn *aCol);
+  nsresult GetRowAt(int32_t aX, int32_t aY, int32_t *aValue);
+  nsresult GetCellAt(int32_t aX, int32_t aY, int32_t *aRow,
+                     nsITreeColumn **aCol, nsACString &aChildElt);
+  nsresult GetCoordsForCellItem(int32_t aRow, nsITreeColumn *aCol,
+                                const nsACString &aElt,
+                                int32_t *aX, int32_t *aY,
+                                int32_t *aWidth, int32_t *aHeight);
+  nsresult IsCellCropped(int32_t aRow, nsITreeColumn *aCol, bool *aResult);
+  nsresult RowCountChanged(int32_t aIndex, int32_t aCount);
+  nsresult BeginUpdateBatch();
+  nsresult EndUpdateBatch();
+  nsresult ClearStyleAndImageCaches();
+
+  void CancelImageRequests();
+
+  void ManageReflowCallback(const nsRect& aRect, nscoord aHorzWidth);
+
+  virtual nsSize GetXULMinSize(nsBoxLayoutState& aBoxLayoutState) override;
+  virtual void SetXULBounds(nsBoxLayoutState& aBoxLayoutState, const nsRect& aRect,
+                            bool aRemoveOverflowArea = false) override;
+
+  // nsIReflowCallback
+  virtual bool ReflowFinished() override;
+  virtual void ReflowCallbackCanceled() override;
+
+  // nsICSSPseudoComparator
+  virtual bool PseudoMatches(nsCSSSelector* aSelector) override;
+
+  // nsIScrollbarMediator
+  virtual void ScrollByPage(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                            nsIScrollbarMediator::ScrollSnapMode aSnap
+                              = nsIScrollbarMediator::DISABLE_SNAP) override;
+  virtual void ScrollByWhole(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                             nsIScrollbarMediator::ScrollSnapMode aSnap
+                               = nsIScrollbarMediator::DISABLE_SNAP) override;
+  virtual void ScrollByLine(nsScrollbarFrame* aScrollbar, int32_t aDirection,
+                            nsIScrollbarMediator::ScrollSnapMode aSnap
+                              = nsIScrollbarMediator::DISABLE_SNAP) override;
+  virtual void RepeatButtonScroll(nsScrollbarFrame* aScrollbar) override;
+  virtual void ThumbMoved(nsScrollbarFrame* aScrollbar,
+                          nscoord aOldPos,
+                          nscoord aNewPos) override;
+  virtual void ScrollbarReleased(nsScrollbarFrame* aScrollbar) override {}
+  virtual void VisibilityChanged(bool aVisible) override { Invalidate(); }
+  virtual nsIFrame* GetScrollbarBox(bool aVertical) override {
+    ScrollParts parts = GetScrollParts();
+    return aVertical ? parts.mVScrollbar : parts.mHScrollbar;
+  }
+  virtual void ScrollbarActivityStarted() const override;
+  virtual void ScrollbarActivityStopped() const override;
+  virtual bool IsScrollbarOnRight() const override {
+    return (StyleVisibility()->mDirection == NS_STYLE_DIRECTION_LTR);
+  }
+  virtual bool ShouldSuppressScrollbarRepaints() const override {
+    return false;
+  }
+
+  // Overridden from nsIFrame to cache our pres context.
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual nsresult GetCursor(const nsPoint& aPoint,
+                             nsIFrame::Cursor& aCursor) override;
+
+  virtual nsresult HandleEvent(nsPresContext* aPresContext,
+                               mozilla::WidgetGUIEvent* aEvent,
+                               nsEventStatus* aEventStatus) override;
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) override;
+
+  virtual void DidSetStyleContext(nsStyleContext* aOldStyleContext) override;
+
+  friend nsIFrame* NS_NewTreeBodyFrame(nsIPresShell* aPresShell);
+  friend class nsTreeColumn;
+
+  struct ScrollParts {
+    nsScrollbarFrame*    mVScrollbar;
+    nsCOMPtr<nsIContent> mVScrollbarContent;
+    nsScrollbarFrame*    mHScrollbar;
+    nsCOMPtr<nsIContent> mHScrollbarContent;
+    nsIFrame*            mColumnsFrame;
+    nsIScrollableFrame*  mColumnsScrollFrame;
+  };
+
+  DrawResult PaintTreeBody(nsRenderingContext& aRenderingContext,
+                           const nsRect& aDirtyRect, nsPoint aPt);
+
+  nsITreeBoxObject* GetTreeBoxObject() const { return mTreeBoxObject; }
+
+  // Get the base element, <tree> or <select>
+  nsIContent* GetBaseElement();
+
+  bool GetVerticalOverflow() const { return mVerticalOverflow; }
+  bool GetHorizontalOverflow() const {return mHorizontalOverflow; }
+
+protected:
+  friend class nsOverflowChecker;
+
+  // This method paints a specific column background of the tree.
+  DrawResult PaintColumn(nsTreeColumn*        aColumn,
+                         const nsRect&        aColumnRect,
+                         nsPresContext*       aPresContext,
+                         nsRenderingContext&  aRenderingContext,
+                         const nsRect&        aDirtyRect);
+
+  // This method paints a single row in the tree.
+  DrawResult PaintRow(int32_t              aRowIndex,
+                      const nsRect&        aRowRect,
+                      nsPresContext*       aPresContext,
+                      nsRenderingContext&  aRenderingContext,
+                      const nsRect&        aDirtyRect,
+                      nsPoint              aPt);
+
+  // This method paints a single separator in the tree.
+  DrawResult PaintSeparator(int32_t              aRowIndex,
+                            const nsRect&        aSeparatorRect,
+                            nsPresContext*       aPresContext,
+                            nsRenderingContext&  aRenderingContext,
+                            const nsRect&        aDirtyRect);
+
+  // This method paints a specific cell in a given row of the tree.
+  DrawResult PaintCell(int32_t              aRowIndex, 
+                       nsTreeColumn*        aColumn,
+                       const nsRect&        aCellRect,
+                       nsPresContext*       aPresContext,
+                       nsRenderingContext&  aRenderingContext,
+                       const nsRect&        aDirtyRect,
+                       nscoord&             aCurrX,
+                       nsPoint              aPt);
+
+  // This method paints the twisty inside a cell in the primary column of an tree.
+  DrawResult PaintTwisty(int32_t              aRowIndex,
+                         nsTreeColumn*        aColumn,
+                         const nsRect&        aTwistyRect,
+                         nsPresContext*       aPresContext,
+                         nsRenderingContext&  aRenderingContext,
+                         const nsRect&        aDirtyRect,
+                         nscoord&             aRemainingWidth,
+                         nscoord&             aCurrX);
+
+  // This method paints the image inside the cell of an tree.
+  DrawResult PaintImage(int32_t              aRowIndex,
+                        nsTreeColumn*        aColumn,
+                        const nsRect&        aImageRect,
+                        nsPresContext*       aPresContext,
+                        nsRenderingContext&  aRenderingContext,
+                        const nsRect&        aDirtyRect,
+                        nscoord&             aRemainingWidth,
+                        nscoord&             aCurrX);
+
+  // This method paints the text string inside a particular cell of the tree.
+  DrawResult PaintText(int32_t             aRowIndex,
+                       nsTreeColumn*       aColumn,
+                       const nsRect&       aTextRect,
+                       nsPresContext*      aPresContext,
+                       nsRenderingContext& aRenderingContext,
+                       const nsRect&       aDirtyRect,
+                       nscoord&            aCurrX);
+
+  // This method paints the checkbox inside a particular cell of the tree.
+  DrawResult PaintCheckbox(int32_t              aRowIndex, 
+                           nsTreeColumn*        aColumn,
+                           const nsRect&        aCheckboxRect,
+                           nsPresContext*       aPresContext,
+                           nsRenderingContext&  aRenderingContext,
+                           const nsRect&        aDirtyRect);
+
+  // This method paints the progress meter inside a particular cell of the tree.
+  DrawResult PaintProgressMeter(int32_t              aRowIndex, 
+                                nsTreeColumn*        aColumn,
+                                const nsRect&        aProgressMeterRect,
+                                nsPresContext*       aPresContext,
+                                nsRenderingContext&  aRenderingContext,
+                                const nsRect&        aDirtyRect);
+
+  // This method paints a drop feedback of the tree.
+  DrawResult PaintDropFeedback(const nsRect&        aDropFeedbackRect, 
+                               nsPresContext*       aPresContext,
+                               nsRenderingContext&  aRenderingContext,
+                               const nsRect&        aDirtyRect,
+                               nsPoint              aPt);
+
+  // This method is called with a specific style context and rect to
+  // paint the background rect as if it were a full-blown frame.
+  DrawResult PaintBackgroundLayer(nsStyleContext*      aStyleContext,
+                                  nsPresContext*       aPresContext, 
+                                  nsRenderingContext&  aRenderingContext, 
+                                  const nsRect&        aRect,
+                                  const nsRect&        aDirtyRect);
+
+
+  // An internal hit test.  aX and aY are expected to be in twips in the
+  // coordinate system of this frame.
+  int32_t GetRowAt(nscoord aX, nscoord aY);
+
+  // Check for bidi characters in the text, and if there are any, ensure
+  // that the prescontext is in bidi mode.
+  void CheckTextForBidi(nsAutoString& aText);
+
+  void AdjustForCellText(nsAutoString& aText,
+                         int32_t aRowIndex,
+                         nsTreeColumn* aColumn,
+                         nsRenderingContext& aRenderingContext,
+                         nsFontMetrics& aFontMetrics,
+                         nsRect& aTextRect);
+
+  // A helper used when hit testing.
+  nsIAtom* GetItemWithinCellAt(nscoord aX, const nsRect& aCellRect,
+                               int32_t aRowIndex, nsTreeColumn* aColumn);
+
+  // An internal hit test.  aX and aY are expected to be in twips in the
+  // coordinate system of this frame.
+  void GetCellAt(nscoord aX, nscoord aY, int32_t* aRow, nsTreeColumn** aCol,
+                 nsIAtom** aChildElt);
+
+  // Retrieve the area for the twisty for a cell.
+  nsITheme* GetTwistyRect(int32_t aRowIndex,
+                          nsTreeColumn* aColumn,
+                          nsRect& aImageRect,
+                          nsRect& aTwistyRect,
+                          nsPresContext* aPresContext,
+                          nsStyleContext* aTwistyContext);
+
+  // Fetch an image from the image cache.
+  nsresult GetImage(int32_t aRowIndex, nsTreeColumn* aCol, bool aUseContext,
+                    nsStyleContext* aStyleContext, bool& aAllowImageRegions, imgIContainer** aResult);
+
+  // Returns the size of a given image.   This size *includes* border and
+  // padding.  It does not include margins.
+  nsRect GetImageSize(int32_t aRowIndex, nsTreeColumn* aCol, bool aUseContext, nsStyleContext* aStyleContext);
+
+  // Returns the destination size of the image, not including borders and padding.
+  nsSize GetImageDestSize(nsStyleContext* aStyleContext, bool useImageRegion, imgIContainer* image);
+
+  // Returns the source rectangle of the image to be displayed.
+  nsRect GetImageSourceRect(nsStyleContext* aStyleContext, bool useImageRegion, imgIContainer* image);
+
+  // Returns the height of rows in the tree.
+  int32_t GetRowHeight();
+
+  // Returns our indentation width.
+  int32_t GetIndentation();
+
+  // Calculates our width/height once border and padding have been removed.
+  void CalcInnerBox();
+
+  // Calculate the total width of our scrollable portion
+  nscoord CalcHorzWidth(const ScrollParts& aParts);
+
+  // Looks up a style context in the style cache.  On a cache miss we resolve
+  // the pseudo-styles passed in and place them into the cache.
+  nsStyleContext* GetPseudoStyleContext(nsIAtom* aPseudoElement);
+
+  // Retrieves the scrollbars and scrollview relevant to this treebody. We
+  // traverse the frame tree under our base element, in frame order, looking
+  // for the first relevant vertical scrollbar, horizontal scrollbar, and
+  // scrollable frame (with associated content and scrollable view). These
+  // are all volatile and should not be retained.
+  ScrollParts GetScrollParts();
+
+  // Update the curpos of the scrollbar.
+  void UpdateScrollbars(const ScrollParts& aParts);
+
+  // Update the maxpos of the scrollbar.
+  void InvalidateScrollbars(const ScrollParts& aParts, nsWeakFrame& aWeakColumnsFrame);
+
+  // Check overflow and generate events.
+  void CheckOverflow(const ScrollParts& aParts);
+
+  // Calls UpdateScrollbars, Invalidate aNeedsFullInvalidation if true,
+  // InvalidateScrollbars and finally CheckOverflow.
+  // returns true if the frame is still alive after the method call.
+  bool FullScrollbarsUpdate(bool aNeedsFullInvalidation);
+
+  // Use to auto-fill some of the common properties without the view having to do it.
+  // Examples include container, open, selected, and focus.
+  void PrefillPropertyArray(int32_t aRowIndex, nsTreeColumn* aCol);
+
+  // Our internal scroll method, used by all the public scroll methods.
+  nsresult ScrollInternal(const ScrollParts& aParts, int32_t aRow);
+  nsresult ScrollToRowInternal(const ScrollParts& aParts, int32_t aRow);
+  nsresult ScrollToColumnInternal(const ScrollParts& aParts, nsITreeColumn* aCol);
+  nsresult ScrollHorzInternal(const ScrollParts& aParts, int32_t aPosition);
+  nsresult EnsureRowIsVisibleInternal(const ScrollParts& aParts, int32_t aRow);
+
+  // Convert client pixels into appunits in our coordinate space.
+  nsPoint AdjustClientCoordsToBoxCoordSpace(int32_t aX, int32_t aY);
+
+  // Cache the box object
+  void EnsureBoxObject();
+
+  void EnsureView();
+
+  nsresult GetCellWidth(int32_t aRow, nsTreeColumn* aCol,
+                        nsRenderingContext* aRenderingContext,
+                        nscoord& aDesiredSize, nscoord& aCurrentSize);
+  nscoord CalcMaxRowWidth();
+
+  // Translate the given rect horizontally from tree coordinates into the
+  // coordinate system of our nsTreeBodyFrame.  If clip is true, then clip the
+  // rect to its intersection with mInnerBox in the horizontal direction.
+  // Return whether the result has a nonempty intersection with mInnerBox
+  // after projecting both onto the horizontal coordinate axis.
+  bool OffsetForHorzScroll(nsRect& rect, bool clip);
+
+  bool CanAutoScroll(int32_t aRowIndex);
+
+  // Calc the row and above/below/on status given where the mouse currently is hovering.
+  // Also calc if we're in the region in which we want to auto-scroll the tree.
+  // A positive value of |aScrollLines| means scroll down, a negative value
+  // means scroll up, a zero value means that we aren't in drag scroll region.
+  void ComputeDropPosition(mozilla::WidgetGUIEvent* aEvent,
+                           int32_t* aRow,
+                           int16_t* aOrient,
+                           int16_t* aScrollLines);
+
+  // Mark ourselves dirty if we're a select widget
+  void MarkDirtyIfSelect();
+
+  void InvalidateDropFeedback(int32_t aRow, int16_t aOrientation) {
+    InvalidateRow(aRow);
+    if (aOrientation != nsITreeView::DROP_ON)
+      InvalidateRow(aRow + aOrientation);
+  }
+
+public:
+  static
+  already_AddRefed<nsTreeColumn> GetColumnImpl(nsITreeColumn* aUnknownCol) {
+    if (!aUnknownCol)
+      return nullptr;
+
+    nsCOMPtr<nsTreeColumn> col = do_QueryInterface(aUnknownCol);
+    return col.forget();
+  }
+
+  /**
+   * Remove an nsITreeImageListener from being tracked by this frame. Only tree
+   * image listeners that are created by this frame are tracked.
+   *
+   * @param aListener A pointer to an nsTreeImageListener to no longer
+   *        track.
+   */
+  void RemoveTreeImageListener(nsTreeImageListener* aListener);
+
+protected:
+
+  // Create a new timer. This method is used to delay various actions like
+  // opening/closing folders or tree scrolling.
+  // aID is type of the action, aFunc is the function to be called when
+  // the timer fires and aType is type of timer - one shot or repeating.
+  nsresult CreateTimer(const mozilla::LookAndFeel::IntID aID,
+                       nsTimerCallbackFunc aFunc, int32_t aType,
+                       nsITimer** aTimer);
+
+  static void OpenCallback(nsITimer *aTimer, void *aClosure);
+
+  static void CloseCallback(nsITimer *aTimer, void *aClosure);
+
+  static void LazyScrollCallback(nsITimer *aTimer, void *aClosure);
+
+  static void ScrollCallback(nsITimer *aTimer, void *aClosure);
+
+  class ScrollEvent : public mozilla::Runnable {
+  public:
+    NS_DECL_NSIRUNNABLE
+    explicit ScrollEvent(nsTreeBodyFrame *aInner) : mInner(aInner) {}
+    void Revoke() { mInner = nullptr; }
+  private:
+    nsTreeBodyFrame* mInner;
+  };
+
+  void PostScrollEvent();
+  void FireScrollEvent();
+
+  /**
+   * Clear the pointer to this frame for all nsTreeImageListeners that were
+   * created by this frame.
+   */
+  void DetachImageListeners();
+
+#ifdef ACCESSIBILITY
+  /**
+   * Fires 'treeRowCountChanged' event asynchronously. The event supports
+   * nsIDOMCustomEvent interface that is used to expose the following
+   * information structures.
+   *
+   * @param aIndex  the row index rows are added/removed from
+   * @param aCount  the number of added/removed rows (the sign points to
+   *                an operation, plus - addition, minus - removing)
+   */
+  void FireRowCountChangedEvent(int32_t aIndex, int32_t aCount);
+
+  /**
+   * Fires 'treeInvalidated' event asynchronously. The event supports
+   * nsIDOMCustomEvent interface that is used to expose the information
+   * structures described by method arguments.
+   *
+   * @param aStartRow  the start index of invalidated rows, -1 means that
+   *                   columns have been invalidated only
+   * @param aEndRow    the end index of invalidated rows, -1 means that columns
+   *                   have been invalidated only
+   * @param aStartCol  the start invalidated column, nullptr means that only rows
+   *                   have been invalidated
+   * @param aEndCol    the end invalidated column, nullptr means that rows have
+   *                   been invalidated only
+   */
+  void FireInvalidateEvent(int32_t aStartRow, int32_t aEndRow,
+                           nsITreeColumn *aStartCol, nsITreeColumn *aEndCol);
+#endif
+
+protected: // Data Members
+
+  class Slots {
+    public:
+      Slots() {
+      }
+
+      ~Slots() {
+        if (mTimer)
+          mTimer->Cancel();
+      }
+
+      friend class nsTreeBodyFrame;
+
+    protected:
+      // If the drop is actually allowed here or not.
+      bool                     mDropAllowed;
+
+      // True while dragging over the tree.
+      bool mIsDragging;
+
+      // The row the mouse is hovering over during a drop.
+      int32_t                  mDropRow;
+
+      // Where we want to draw feedback (above/on this row/below) if allowed.
+      int16_t                  mDropOrient;
+
+      // Number of lines to be scrolled.
+      int16_t                  mScrollLines;
+
+      // The drag action that was received for this slot
+      uint32_t                 mDragAction;
+
+      // Timer for opening/closing spring loaded folders or scrolling the tree.
+      nsCOMPtr<nsITimer>       mTimer;
+
+      // An array used to keep track of all spring loaded folders.
+      nsTArray<int32_t>        mArray;
+  };
+
+  Slots* mSlots;
+
+  nsRevocableEventPtr<ScrollEvent> mScrollEvent;
+
+  RefPtr<ScrollbarActivity> mScrollbarActivity;
+
+  // The cached box object parent.
+  nsCOMPtr<nsITreeBoxObject> mTreeBoxObject;
+
+  // Cached column information.
+  RefPtr<nsTreeColumns> mColumns;
+
+  // The current view for this tree widget.  We get all of our row and cell data
+  // from the view.
+  nsCOMPtr<nsITreeView> mView;
+
+  // A cache of all the style contexts we have seen for rows and cells of the tree.  This is a mapping from
+  // a list of atoms to a corresponding style context.  This cache stores every combination that
+  // occurs in the tree, so for n distinct properties, this cache could have 2 to the n entries
+  // (the power set of all row properties).
+  nsTreeStyleCache mStyleCache;
+
+  // A hashtable that maps from URLs to image request/listener pairs.  The URL
+  // is provided by the view or by the style context. The style context
+  // represents a resolved :-moz-tree-cell-image (or twisty) pseudo-element.
+  // It maps directly to an imgIRequest.
+  nsDataHashtable<nsStringHashKey, nsTreeImageCacheEntry> mImageCache;
+
+  // A scratch array used when looking up cached style contexts.
+  AtomArray mScratchArray;
+
+  // The index of the first visible row and the # of rows visible onscreen.  
+  // The tree only examines onscreen rows, starting from
+  // this index and going up to index+pageLength.
+  int32_t mTopRowIndex;
+  int32_t mPageLength;
+
+  // The horizontal scroll position
+  nscoord mHorzPosition;
+
+  // The original desired horizontal width before changing it and posting a
+  // reflow callback. In some cases, the desired horizontal width can first be
+  // different from the current desired horizontal width, only to return to
+  // the same value later during the same reflow. In this case, we can cancel
+  // the posted reflow callback and prevent an unnecessary reflow.
+  nscoord mOriginalHorzWidth;
+  // Our desired horizontal width (the width for which we actually have tree
+  // columns).
+  nscoord mHorzWidth;
+  // The amount by which to adjust the width of the last cell.
+  // This depends on whether or not the columnpicker and scrollbars are present.
+  nscoord mAdjustWidth;
+
+  // Cached heights and indent info.
+  nsRect mInnerBox; // 4-byte aligned
+  int32_t mRowHeight;
+  int32_t mIndentation;
+  nscoord mStringWidth;
+
+  int32_t mUpdateBatchNest;
+
+  // Cached row count.
+  int32_t mRowCount;
+
+  // The row the mouse is hovering over.
+  int32_t mMouseOverRow;
+
+  // Whether or not we're currently focused.
+  bool mFocused;
+
+  // Do we have a fixed number of onscreen rows?
+  bool mHasFixedRowCount;
+
+  bool mVerticalOverflow;
+  bool mHorizontalOverflow;
+
+  bool mReflowCallbackPosted;
+
+  // Set while we flush layout to take account of effects of
+  // overflow/underflow event handlers
+  bool mCheckingOverflow;
+
+  // Hash table to keep track of which listeners we created and thus
+  // have pointers to us.
+  nsTHashtable<nsPtrHashKey<nsTreeImageListener> > mCreatedListeners;
+
+}; // class nsTreeBodyFrame
+
+#endif
diff --git a/layout/xul/tree/nsTreeColFrame.cpp b/layout/xul/tree/nsTreeColFrame.cpp
new file mode 100644
index 0000000000..649c0b0b4c
--- /dev/null
+++ b/layout/xul/tree/nsTreeColFrame.cpp
@@ -0,0 +1,201 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMPtr.h"
+#include "nsTreeColFrame.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+#include "nsStyleContext.h"
+#include "nsNameSpaceManager.h"
+#include "nsIBoxObject.h"
+#include "mozilla/dom/TreeBoxObject.h"
+#include "nsIDOMElement.h"
+#include "nsITreeColumns.h"
+#include "nsIDOMXULTreeElement.h"
+#include "nsDisplayList.h"
+#include "nsTreeBodyFrame.h"
+
+//
+// NS_NewTreeColFrame
+//
+// Creates a new col frame
+//
+nsIFrame*
+NS_NewTreeColFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsTreeColFrame(aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsTreeColFrame)
+
+// Destructor
+nsTreeColFrame::~nsTreeColFrame()
+{
+}
+
+void
+nsTreeColFrame::Init(nsIContent*       aContent,
+                     nsContainerFrame* aParent,
+                     nsIFrame*         aPrevInFlow)
+{
+  nsBoxFrame::Init(aContent, aParent, aPrevInFlow);
+  InvalidateColumns();
+}
+
+void
+nsTreeColFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  InvalidateColumns(false);
+  nsBoxFrame::DestroyFrom(aDestructRoot);
+}
+
+class nsDisplayXULTreeColSplitterTarget : public nsDisplayItem {
+public:
+  nsDisplayXULTreeColSplitterTarget(nsDisplayListBuilder* aBuilder,
+                                    nsIFrame* aFrame) :
+    nsDisplayItem(aBuilder, aFrame) {
+    MOZ_COUNT_CTOR(nsDisplayXULTreeColSplitterTarget);
+  }
+#ifdef NS_BUILD_REFCNT_LOGGING
+  virtual ~nsDisplayXULTreeColSplitterTarget() {
+    MOZ_COUNT_DTOR(nsDisplayXULTreeColSplitterTarget);
+  }
+#endif
+
+  virtual void HitTest(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
+                       HitTestState* aState,
+                       nsTArray<nsIFrame*> *aOutFrames) override;
+  NS_DISPLAY_DECL_NAME("XULTreeColSplitterTarget", TYPE_XUL_TREE_COL_SPLITTER_TARGET)
+};
+
+void
+nsDisplayXULTreeColSplitterTarget::HitTest(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
+                                           HitTestState* aState, nsTArray<nsIFrame*> *aOutFrames)
+{
+  nsRect rect = aRect - ToReferenceFrame();
+  // If we are in either in the first 4 pixels or the last 4 pixels, we're going to
+  // do something really strange.  Check for an adjacent splitter.
+  bool left = false;
+  bool right = false;
+  if (mFrame->GetSize().width - nsPresContext::CSSPixelsToAppUnits(4) <= rect.XMost()) {
+    right = true;
+  } else if (nsPresContext::CSSPixelsToAppUnits(4) > rect.x) {
+    left = true;
+  }
+
+  // Swap left and right for RTL trees in order to find the correct splitter
+  if (mFrame->StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL) {
+    bool tmp = left;
+    left = right;
+    right = tmp;
+  }
+
+  if (left || right) {
+    // We are a header. Look for the correct splitter.
+    nsIFrame* child;
+    if (left)
+      child = mFrame->GetPrevSibling();
+    else
+      child = mFrame->GetNextSibling();
+
+    if (child && child->GetContent()->NodeInfo()->Equals(nsGkAtoms::splitter,
+                                                         kNameSpaceID_XUL)) {
+      aOutFrames->AppendElement(child);
+    }
+  }
+
+}
+
+void
+nsTreeColFrame::BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                            const nsRect&           aDirtyRect,
+                                            const nsDisplayListSet& aLists)
+{
+  if (!aBuilder->IsForEventDelivery()) {
+    nsBoxFrame::BuildDisplayListForChildren(aBuilder, aDirtyRect, aLists);
+    return;
+  }
+  
+  nsDisplayListCollection set;
+  nsBoxFrame::BuildDisplayListForChildren(aBuilder, aDirtyRect, set);
+  
+  WrapListsInRedirector(aBuilder, set, aLists);
+
+  aLists.Content()->AppendNewToTop(new (aBuilder)
+    nsDisplayXULTreeColSplitterTarget(aBuilder, this));
+}
+
+nsresult
+nsTreeColFrame::AttributeChanged(int32_t aNameSpaceID,
+                                 nsIAtom* aAttribute,
+                                 int32_t aModType)
+{
+  nsresult rv = nsBoxFrame::AttributeChanged(aNameSpaceID, aAttribute,
+                                             aModType);
+
+  if (aAttribute == nsGkAtoms::ordinal || aAttribute == nsGkAtoms::primary) {
+    InvalidateColumns();
+  }
+
+  return rv;
+}
+
+void
+nsTreeColFrame::SetXULBounds(nsBoxLayoutState& aBoxLayoutState,
+                             const nsRect& aRect,
+                             bool aRemoveOverflowArea)
+{
+  nscoord oldWidth = mRect.width;
+
+  nsBoxFrame::SetXULBounds(aBoxLayoutState, aRect, aRemoveOverflowArea);
+  if (mRect.width != oldWidth) {
+    nsITreeBoxObject* treeBoxObject = GetTreeBoxObject();
+    if (treeBoxObject) {
+      treeBoxObject->Invalidate();
+    }
+  }
+}
+
+nsITreeBoxObject*
+nsTreeColFrame::GetTreeBoxObject()
+{
+  nsITreeBoxObject* result = nullptr;
+
+  nsIContent* parent = mContent->GetParent();
+  if (parent) {
+    nsIContent* grandParent = parent->GetParent();
+    nsCOMPtr<nsIDOMXULElement> treeElement = do_QueryInterface(grandParent);
+    if (treeElement) {
+      nsCOMPtr<nsIBoxObject> boxObject;
+      treeElement->GetBoxObject(getter_AddRefs(boxObject));
+
+      nsCOMPtr<nsITreeBoxObject> treeBoxObject = do_QueryInterface(boxObject);
+      result = treeBoxObject.get();
+    }
+  }
+  return result;
+}
+
+void
+nsTreeColFrame::InvalidateColumns(bool aCanWalkFrameTree)
+{
+  nsITreeBoxObject* treeBoxObject = GetTreeBoxObject();
+  if (treeBoxObject) {
+    nsCOMPtr<nsITreeColumns> columns;
+
+    if (aCanWalkFrameTree) {
+      treeBoxObject->GetColumns(getter_AddRefs(columns));
+    } else {
+      nsTreeBodyFrame* body = static_cast<mozilla::dom::TreeBoxObject*>
+        (treeBoxObject)->GetCachedTreeBodyFrame();
+      if (body) {
+        columns = body->Columns();
+      }
+    }
+
+    if (columns)
+      columns->InvalidateColumns();
+  }
+}
diff --git a/layout/xul/tree/nsTreeColFrame.h b/layout/xul/tree/nsTreeColFrame.h
new file mode 100644
index 0000000000..8fc3219d50
--- /dev/null
+++ b/layout/xul/tree/nsTreeColFrame.h
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+#include "nsBoxFrame.h"
+
+class nsITreeBoxObject;
+
+nsIFrame* NS_NewTreeColFrame(nsIPresShell* aPresShell, 
+                             nsStyleContext* aContext);
+
+class nsTreeColFrame : public nsBoxFrame
+{
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  explicit nsTreeColFrame(nsStyleContext* aContext):
+    nsBoxFrame(aContext) {}
+
+  virtual void Init(nsIContent*       aContent,
+                    nsContainerFrame* aParent,
+                    nsIFrame*         aPrevInFlow) override;
+
+  virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
+
+  virtual void BuildDisplayListForChildren(nsDisplayListBuilder*   aBuilder,
+                                           const nsRect&           aDirtyRect,
+                                           const nsDisplayListSet& aLists) override;
+
+  virtual nsresult AttributeChanged(int32_t aNameSpaceID,
+                                    nsIAtom* aAttribute,
+                                    int32_t aModType) override;
+
+  virtual void SetXULBounds(nsBoxLayoutState& aBoxLayoutState, const nsRect& aRect,
+                            bool aRemoveOverflowArea = false) override;
+
+  friend nsIFrame* NS_NewTreeColFrame(nsIPresShell* aPresShell,
+                                      nsStyleContext* aContext);
+
+protected:
+  virtual ~nsTreeColFrame();
+
+  /**
+   * @return the tree box object of the tree this column belongs to, or nullptr.
+   */
+  nsITreeBoxObject* GetTreeBoxObject();
+
+  /**
+   * Helper method that gets the nsITreeColumns object this column belongs to
+   * and calls InvalidateColumns() on it.
+   */
+  void InvalidateColumns(bool aCanWalkFrameTree = true);
+};
diff --git a/layout/xul/tree/nsTreeColumns.cpp b/layout/xul/tree/nsTreeColumns.cpp
new file mode 100644
index 0000000000..c6ee19342e
--- /dev/null
+++ b/layout/xul/tree/nsTreeColumns.cpp
@@ -0,0 +1,765 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsIDOMElement.h"
+#include "nsIBoxObject.h"
+#include "nsTreeColumns.h"
+#include "nsTreeUtils.h"
+#include "nsStyleContext.h"
+#include "nsDOMClassInfoID.h"
+#include "nsContentUtils.h"
+#include "nsTreeBodyFrame.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/TreeBoxObject.h"
+#include "mozilla/dom/TreeColumnBinding.h"
+#include "mozilla/dom/TreeColumnsBinding.h"
+
+using namespace mozilla;
+
+// Column class that caches all the info about our column.
+nsTreeColumn::nsTreeColumn(nsTreeColumns* aColumns, nsIContent* aContent)
+  : mContent(aContent),
+    mColumns(aColumns),
+    mPrevious(nullptr)
+{
+  NS_ASSERTION(aContent &&
+               aContent->NodeInfo()->Equals(nsGkAtoms::treecol,
+                                            kNameSpaceID_XUL),
+               "nsTreeColumn's content must be a <xul:treecol>");
+
+  Invalidate();
+}
+
+nsTreeColumn::~nsTreeColumn()
+{
+  if (mNext) {
+    mNext->SetPrevious(nullptr);
+  }
+}
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(nsTreeColumn)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsTreeColumn)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mContent)
+  if (tmp->mNext) {
+    tmp->mNext->SetPrevious(nullptr);
+    NS_IMPL_CYCLE_COLLECTION_UNLINK(mNext)
+  }
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsTreeColumn)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mContent)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mNext)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(nsTreeColumn)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsTreeColumn)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsTreeColumn)
+
+// QueryInterface implementation for nsTreeColumn
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsTreeColumn)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsITreeColumn)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+  if (aIID.Equals(NS_GET_IID(nsTreeColumn))) {
+    AddRef();
+    *aInstancePtr = this;
+    return NS_OK;
+  }
+  else
+NS_INTERFACE_MAP_END
+
+nsIFrame*
+nsTreeColumn::GetFrame()
+{
+  NS_ENSURE_TRUE(mContent, nullptr);
+
+  return mContent->GetPrimaryFrame();
+}
+
+bool
+nsTreeColumn::IsLastVisible(nsTreeBodyFrame* aBodyFrame)
+{
+  NS_ASSERTION(GetFrame(), "should have checked for this already");
+
+  // cyclers are fixed width, don't adjust them
+  if (IsCycler())
+    return false;
+
+  // we're certainly not the last visible if we're not visible
+  if (GetFrame()->GetRect().width == 0)
+    return false;
+
+  // try to find a visible successor
+  for (nsTreeColumn *next = GetNext(); next; next = next->GetNext()) {
+    nsIFrame* frame = next->GetFrame();
+    if (frame && frame->GetRect().width > 0)
+      return false;
+  }
+  return true;
+}
+
+nsresult
+nsTreeColumn::GetRect(nsTreeBodyFrame* aBodyFrame, nscoord aY, nscoord aHeight, nsRect* aResult)
+{
+  nsIFrame* frame = GetFrame();
+  if (!frame) {
+    *aResult = nsRect();
+    return NS_ERROR_FAILURE;
+  }
+
+  bool isRTL = aBodyFrame->StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL;
+  *aResult = frame->GetRect();
+  aResult->y = aY;
+  aResult->height = aHeight;
+  if (isRTL)
+    aResult->x += aBodyFrame->mAdjustWidth;
+  else if (IsLastVisible(aBodyFrame))
+    aResult->width += aBodyFrame->mAdjustWidth;
+  return NS_OK;
+}
+
+nsresult
+nsTreeColumn::GetXInTwips(nsTreeBodyFrame* aBodyFrame, nscoord* aResult)
+{
+  nsIFrame* frame = GetFrame();
+  if (!frame) {
+    *aResult = 0;
+    return NS_ERROR_FAILURE;
+  }
+  *aResult = frame->GetRect().x;
+  return NS_OK;
+}
+
+nsresult
+nsTreeColumn::GetWidthInTwips(nsTreeBodyFrame* aBodyFrame, nscoord* aResult)
+{
+  nsIFrame* frame = GetFrame();
+  if (!frame) {
+    *aResult = 0;
+    return NS_ERROR_FAILURE;
+  }
+  *aResult = frame->GetRect().width;
+  if (IsLastVisible(aBodyFrame))
+    *aResult += aBodyFrame->mAdjustWidth;
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsTreeColumn::GetElement(nsIDOMElement** aElement)
+{
+  if (mContent) {
+    return CallQueryInterface(mContent, aElement);
+  }
+  *aElement = nullptr;
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetColumns(nsITreeColumns** aColumns)
+{
+  NS_IF_ADDREF(*aColumns = mColumns);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetX(int32_t* aX)
+{
+  nsIFrame* frame = GetFrame();
+  NS_ENSURE_TRUE(frame, NS_ERROR_FAILURE);
+
+  *aX = nsPresContext::AppUnitsToIntCSSPixels(frame->GetRect().x);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetWidth(int32_t* aWidth)
+{
+  nsIFrame* frame = GetFrame();
+  NS_ENSURE_TRUE(frame, NS_ERROR_FAILURE);
+
+  *aWidth = nsPresContext::AppUnitsToIntCSSPixels(frame->GetRect().width);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetId(nsAString& aId)
+{
+  aId = GetId();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetIdConst(const char16_t** aIdConst)
+{
+  *aIdConst = mId.get();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetAtom(nsIAtom** aAtom)
+{
+  NS_IF_ADDREF(*aAtom = GetAtom());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetIndex(int32_t* aIndex)
+{
+  *aIndex = GetIndex();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetPrimary(bool* aPrimary)
+{
+  *aPrimary = IsPrimary();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetCycler(bool* aCycler)
+{
+  *aCycler = IsCycler();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetEditable(bool* aEditable)
+{
+  *aEditable = IsEditable();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetSelectable(bool* aSelectable)
+{
+  *aSelectable = IsSelectable();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetType(int16_t* aType)
+{
+  *aType = GetType();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetNext(nsITreeColumn** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetNext());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::GetPrevious(nsITreeColumn** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetPrevious());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumn::Invalidate()
+{
+  nsIFrame* frame = GetFrame();
+  NS_ENSURE_TRUE(frame, NS_ERROR_FAILURE);
+
+  // Fetch the Id.
+  mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::id, mId);
+
+  // If we have an Id, cache the Id as an atom.
+  if (!mId.IsEmpty()) {
+    mAtom = NS_Atomize(mId);
+  }
+
+  // Cache our index.
+  nsTreeUtils::GetColumnIndex(mContent, &mIndex);
+
+  const nsStyleVisibility* vis = frame->StyleVisibility();
+
+  // Cache our text alignment policy.
+  const nsStyleText* textStyle = frame->StyleText();
+
+  mTextAlignment = textStyle->mTextAlign;
+  // START or END alignment sometimes means RIGHT
+  if ((mTextAlignment == NS_STYLE_TEXT_ALIGN_START &&
+       vis->mDirection == NS_STYLE_DIRECTION_RTL) ||
+      (mTextAlignment == NS_STYLE_TEXT_ALIGN_END &&
+       vis->mDirection == NS_STYLE_DIRECTION_LTR)) {
+    mTextAlignment = NS_STYLE_TEXT_ALIGN_RIGHT;
+  } else if (mTextAlignment == NS_STYLE_TEXT_ALIGN_START ||
+             mTextAlignment == NS_STYLE_TEXT_ALIGN_END) {
+    mTextAlignment = NS_STYLE_TEXT_ALIGN_LEFT;
+  }
+
+  // Figure out if we're the primary column (that has to have indentation
+  // and twisties drawn.
+  mIsPrimary = mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::primary,
+                                     nsGkAtoms::_true, eCaseMatters);
+
+  // Figure out if we're a cycling column (one that doesn't cause a selection
+  // to happen).
+  mIsCycler = mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::cycler,
+                                    nsGkAtoms::_true, eCaseMatters);
+
+  mIsEditable = mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::editable,
+                                     nsGkAtoms::_true, eCaseMatters);
+
+  mIsSelectable = !mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::selectable,
+                                         nsGkAtoms::_false, eCaseMatters);
+
+  mOverflow = mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::overflow,
+                                    nsGkAtoms::_true, eCaseMatters);
+
+  // Figure out our column type. Default type is text.
+  mType = nsITreeColumn::TYPE_TEXT;
+  static nsIContent::AttrValuesArray typestrings[] =
+    {&nsGkAtoms::checkbox, &nsGkAtoms::progressmeter, &nsGkAtoms::password,
+     nullptr};
+  switch (mContent->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::type,
+                                    typestrings, eCaseMatters)) {
+    case 0: mType = nsITreeColumn::TYPE_CHECKBOX; break;
+    case 1: mType = nsITreeColumn::TYPE_PROGRESSMETER; break;
+    case 2: mType = nsITreeColumn::TYPE_PASSWORD; break;
+  }
+
+  // Fetch the crop style.
+  mCropStyle = 0;
+  static nsIContent::AttrValuesArray cropstrings[] =
+    {&nsGkAtoms::center, &nsGkAtoms::left, &nsGkAtoms::start, nullptr};
+  switch (mContent->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::crop,
+                                    cropstrings, eCaseMatters)) {
+    case 0:
+      mCropStyle = 1;
+      break;
+    case 1:
+    case 2:
+      mCropStyle = 2;
+      break;
+  }
+
+  return NS_OK;
+}
+
+nsIContent*
+nsTreeColumn::GetParentObject() const
+{
+  return mContent;
+}
+
+/* virtual */ JSObject*
+nsTreeColumn::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return dom::TreeColumnBinding::Wrap(aCx, this, aGivenProto);
+}
+
+mozilla::dom::Element*
+nsTreeColumn::GetElement(mozilla::ErrorResult& aRv)
+{
+  nsCOMPtr<nsIDOMElement> element;
+  aRv = GetElement(getter_AddRefs(element));
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+  nsCOMPtr<nsINode> node = do_QueryInterface(element);
+  return node->AsElement();
+}
+
+int32_t
+nsTreeColumn::GetX(mozilla::ErrorResult& aRv)
+{
+  int32_t x;
+  aRv = GetX(&x);
+  return x;
+}
+
+int32_t
+nsTreeColumn::GetWidth(mozilla::ErrorResult& aRv)
+{
+  int32_t width;
+  aRv = GetWidth(&width);
+  return width;
+}
+
+void
+nsTreeColumn::Invalidate(mozilla::ErrorResult& aRv)
+{
+  aRv = Invalidate();
+}
+
+nsTreeColumns::nsTreeColumns(nsTreeBodyFrame* aTree)
+  : mTree(aTree)
+{
+}
+
+nsTreeColumns::~nsTreeColumns()
+{
+  nsTreeColumns::InvalidateColumns();
+}
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_0(nsTreeColumns)
+
+// QueryInterface implementation for nsTreeColumns
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsTreeColumns)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsITreeColumns)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+                                                                                
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsTreeColumns)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsTreeColumns)
+
+nsIContent*
+nsTreeColumns::GetParentObject() const
+{
+  return mTree ? mTree->GetBaseElement() : nullptr;
+}
+
+/* virtual */ JSObject*
+nsTreeColumns::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return dom::TreeColumnsBinding::Wrap(aCx, this, aGivenProto);
+}
+
+dom::TreeBoxObject*
+nsTreeColumns::GetTree() const
+{
+  return mTree ? static_cast<mozilla::dom::TreeBoxObject*>(mTree->GetTreeBoxObject()) : nullptr;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetTree(nsITreeBoxObject** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetTree());
+  return NS_OK;
+}
+
+uint32_t
+nsTreeColumns::Count()
+{
+  EnsureColumns();
+  uint32_t count = 0;
+  for (nsTreeColumn* currCol = mFirstColumn; currCol; currCol = currCol->GetNext()) {
+    ++count;
+  }
+  return count;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetCount(int32_t* _retval)
+{
+  *_retval = Count();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetLength(int32_t* _retval)
+{
+  *_retval = Length();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetFirstColumn(nsITreeColumn** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetFirstColumn());
+  return NS_OK;
+}
+
+nsTreeColumn*
+nsTreeColumns::GetLastColumn()
+{
+  EnsureColumns();
+  nsTreeColumn* currCol = mFirstColumn;
+  while (currCol) {
+    nsTreeColumn* next = currCol->GetNext();
+    if (!next) {
+      return currCol;
+    }
+    currCol = next;
+  }
+  return nullptr;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetLastColumn(nsITreeColumn** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetLastColumn());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetPrimaryColumn(nsITreeColumn** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetPrimaryColumn());
+  return NS_OK;
+}
+
+nsTreeColumn*
+nsTreeColumns::GetSortedColumn()
+{
+  EnsureColumns();
+  for (nsTreeColumn* currCol = mFirstColumn; currCol; currCol = currCol->GetNext()) {
+    if (currCol->mContent &&
+        nsContentUtils::HasNonEmptyAttr(currCol->mContent, kNameSpaceID_None,
+                                        nsGkAtoms::sortDirection)) {
+      return currCol;
+    }
+  }
+  return nullptr;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetSortedColumn(nsITreeColumn** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetSortedColumn());
+  return NS_OK;
+}
+
+nsTreeColumn*
+nsTreeColumns::GetKeyColumn()
+{
+  EnsureColumns();
+
+  nsTreeColumn* first = nullptr;
+  nsTreeColumn* primary = nullptr;
+  nsTreeColumn* sorted = nullptr;
+
+  for (nsTreeColumn* currCol = mFirstColumn; currCol; currCol = currCol->GetNext()) {
+    // Skip hidden columns.
+    if (!currCol->mContent ||
+        currCol->mContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::hidden,
+                                       nsGkAtoms::_true, eCaseMatters))
+      continue;
+
+    // Skip non-text column
+    if (currCol->GetType() != nsITreeColumn::TYPE_TEXT)
+      continue;
+
+    if (!first)
+      first = currCol;
+    
+    if (nsContentUtils::HasNonEmptyAttr(currCol->mContent, kNameSpaceID_None,
+                                        nsGkAtoms::sortDirection)) {
+      // Use sorted column as the key.
+      sorted = currCol;
+      break;
+    }
+
+    if (currCol->IsPrimary())
+      if (!primary)
+        primary = currCol;
+  }
+
+  if (sorted)
+    return sorted;
+  if (primary)
+    return primary;
+  return first;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetKeyColumn(nsITreeColumn** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetKeyColumn());
+  return NS_OK;
+}
+
+nsTreeColumn*
+nsTreeColumns::GetColumnFor(dom::Element* aElement)
+{
+  EnsureColumns();
+  for (nsTreeColumn* currCol = mFirstColumn; currCol; currCol = currCol->GetNext()) {
+    if (currCol->mContent == aElement) {
+      return currCol;
+    }
+  }
+  return nullptr;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetColumnFor(nsIDOMElement* aElement, nsITreeColumn** _retval)
+{
+  nsCOMPtr<dom::Element> element = do_QueryInterface(aElement);
+  NS_ADDREF(*_retval = GetColumnFor(element));
+  return NS_OK;
+}
+
+nsTreeColumn*
+nsTreeColumns::NamedGetter(const nsAString& aId, bool& aFound)
+{
+  EnsureColumns();
+  for (nsTreeColumn* currCol = mFirstColumn; currCol; currCol = currCol->GetNext()) {
+    if (currCol->GetId().Equals(aId)) {
+      aFound = true;
+      return currCol;
+    }
+  }
+  aFound = false;
+  return nullptr;
+}
+
+nsTreeColumn*
+nsTreeColumns::GetNamedColumn(const nsAString& aId)
+{
+  bool dummy;
+  return NamedGetter(aId, dummy);
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetNamedColumn(const nsAString& aId, nsITreeColumn** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetNamedColumn(aId));
+  return NS_OK;
+}
+
+void
+nsTreeColumns::GetSupportedNames(nsTArray<nsString>& aNames)
+{
+  for (nsTreeColumn* currCol = mFirstColumn; currCol; currCol = currCol->GetNext()) {
+    aNames.AppendElement(currCol->GetId());
+  }
+}
+
+
+nsTreeColumn*
+nsTreeColumns::IndexedGetter(uint32_t aIndex, bool& aFound)
+{
+  EnsureColumns();
+  for (nsTreeColumn* currCol = mFirstColumn; currCol; currCol = currCol->GetNext()) {
+    if (currCol->GetIndex() == static_cast<int32_t>(aIndex)) {
+      aFound = true;
+      return currCol;
+    }
+  }
+  aFound = false;
+  return nullptr;
+}
+
+nsTreeColumn*
+nsTreeColumns::GetColumnAt(uint32_t aIndex)
+{
+  bool dummy;
+  return IndexedGetter(aIndex, dummy);
+}
+
+NS_IMETHODIMP
+nsTreeColumns::GetColumnAt(int32_t aIndex, nsITreeColumn** _retval)
+{
+  NS_IF_ADDREF(*_retval = GetColumnAt(static_cast<uint32_t>(aIndex)));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::InvalidateColumns()
+{
+  for (nsTreeColumn* currCol = mFirstColumn; currCol;
+       currCol = currCol->GetNext()) {
+    currCol->SetColumns(nullptr);
+  }
+  mFirstColumn = nullptr;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeColumns::RestoreNaturalOrder()
+{
+  if (!mTree)
+    return NS_OK;
+
+  nsIContent* content = mTree->GetBaseElement();
+
+  // Strong ref, since we'll be setting attributes
+  nsCOMPtr<nsIContent> colsContent =
+    nsTreeUtils::GetImmediateChild(content, nsGkAtoms::treecols);
+  if (!colsContent)
+    return NS_OK;
+
+  for (uint32_t i = 0; i < colsContent->GetChildCount(); ++i) {
+    nsCOMPtr<nsIContent> child = colsContent->GetChildAt(i);
+    nsAutoString ordinal;
+    ordinal.AppendInt(i);
+    child->SetAttr(kNameSpaceID_None, nsGkAtoms::ordinal, ordinal, true);
+  }
+
+  nsTreeColumns::InvalidateColumns();
+
+  if (mTree) {
+    mTree->Invalidate();
+  }
+  return NS_OK;
+}
+
+nsTreeColumn*
+nsTreeColumns::GetPrimaryColumn()
+{
+  EnsureColumns();
+  for (nsTreeColumn* currCol = mFirstColumn; currCol; currCol = currCol->GetNext()) {
+    if (currCol->IsPrimary()) {
+      return currCol;
+    }
+  }
+  return nullptr;
+}
+
+void
+nsTreeColumns::EnsureColumns()
+{
+  if (mTree && !mFirstColumn) {
+    nsIContent* treeContent = mTree->GetBaseElement();
+    nsIContent* colsContent =
+      nsTreeUtils::GetDescendantChild(treeContent, nsGkAtoms::treecols);
+    if (!colsContent)
+      return;
+
+    nsIContent* colContent =
+      nsTreeUtils::GetDescendantChild(colsContent, nsGkAtoms::treecol);
+    if (!colContent)
+      return;
+
+    nsIFrame* colFrame = colContent->GetPrimaryFrame();
+    if (!colFrame)
+      return;
+
+    colFrame = colFrame->GetParent();
+    if (!colFrame)
+      return;
+
+    colFrame = colFrame->PrincipalChildList().FirstChild();
+    if (!colFrame)
+      return;
+
+    // Now that we have the first visible column,
+    // we can enumerate the columns in visible order
+    nsTreeColumn* currCol = nullptr;
+    while (colFrame) {
+      nsIContent* colContent = colFrame->GetContent();
+
+      if (colContent->NodeInfo()->Equals(nsGkAtoms::treecol,
+                                         kNameSpaceID_XUL)) {
+        // Create a new column structure.
+        nsTreeColumn* col = new nsTreeColumn(this, colContent);
+        if (!col)
+          return;
+
+        if (currCol) {
+          currCol->SetNext(col);
+          col->SetPrevious(currCol);
+        }
+        else {
+          mFirstColumn = col;
+        }
+        currCol = col;
+      }
+
+      colFrame = colFrame->GetNextSibling();
+    }
+  }
+}
diff --git a/layout/xul/tree/nsTreeColumns.h b/layout/xul/tree/nsTreeColumns.h
new file mode 100644
index 0000000000..0e27c6a036
--- /dev/null
+++ b/layout/xul/tree/nsTreeColumns.h
@@ -0,0 +1,215 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTreeColumns_h__
+#define nsTreeColumns_h__
+
+#include "nsITreeColumns.h"
+#include "nsITreeBoxObject.h"
+#include "mozilla/Attributes.h"
+#include "nsCoord.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsWrapperCache.h"
+#include "nsString.h"
+
+class nsTreeBodyFrame;
+class nsTreeColumns;
+class nsIFrame;
+class nsIContent;
+struct nsRect;
+
+namespace mozilla {
+class ErrorResult;
+namespace dom {
+class Element;
+class TreeBoxObject;
+} // namespace dom
+} // namespace mozilla
+
+#define NS_TREECOLUMN_IMPL_CID                       \
+{ /* 02cd1963-4b5d-4a6c-9223-814d3ade93a3 */         \
+    0x02cd1963,                                      \
+    0x4b5d,                                          \
+    0x4a6c,                                          \
+    {0x92, 0x23, 0x81, 0x4d, 0x3a, 0xde, 0x93, 0xa3} \
+}
+
+// This class is our column info.  We use it to iterate our columns and to obtain
+// information about each column.
+class nsTreeColumn final : public nsITreeColumn
+                         , public nsWrapperCache
+{
+public:
+  nsTreeColumn(nsTreeColumns* aColumns, nsIContent* aContent);
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_TREECOLUMN_IMPL_CID)
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(nsTreeColumn)
+  NS_DECL_NSITREECOLUMN
+
+  // WebIDL
+  nsIContent* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+
+  mozilla::dom::Element* GetElement(mozilla::ErrorResult& aRv);
+
+  nsTreeColumns* GetColumns() const { return mColumns; }
+
+  int32_t GetX(mozilla::ErrorResult& aRv);
+  int32_t GetWidth(mozilla::ErrorResult& aRv);
+
+  // GetId is fine
+  int32_t Index() const { return mIndex; }
+
+  bool Primary() const { return mIsPrimary; }
+  bool Cycler() const { return mIsCycler; }
+  bool Editable() const { return mIsEditable; }
+  bool Selectable() const { return mIsSelectable; }
+  int16_t Type() const { return mType; }
+
+  nsTreeColumn* GetNext() const { return mNext; }
+  nsTreeColumn* GetPrevious() const { return mPrevious; }
+
+  void Invalidate(mozilla::ErrorResult& aRv);
+
+  friend class nsTreeBodyFrame;
+  friend class nsTreeColumns;
+
+protected:
+  ~nsTreeColumn();
+  nsIFrame* GetFrame();
+  nsIFrame* GetFrame(nsTreeBodyFrame* aBodyFrame);
+  // Don't call this if GetWidthInTwips or GetRect fails
+  bool IsLastVisible(nsTreeBodyFrame* aBodyFrame);
+
+  /**
+   * Returns a rect with x and width taken from the frame's rect and specified
+   * y and height. May fail in case there's no frame for the column.
+   */
+  nsresult GetRect(nsTreeBodyFrame* aBodyFrame, nscoord aY, nscoord aHeight,
+                   nsRect* aResult);
+
+  nsresult GetXInTwips(nsTreeBodyFrame* aBodyFrame, nscoord* aResult);
+  nsresult GetWidthInTwips(nsTreeBodyFrame* aBodyFrame, nscoord* aResult);
+
+  void SetColumns(nsTreeColumns* aColumns) { mColumns = aColumns; }
+
+  const nsAString& GetId() { return mId; }
+  nsIAtom* GetAtom() { return mAtom; }
+
+  int32_t GetIndex() { return mIndex; }
+
+  bool IsPrimary() { return mIsPrimary; }
+  bool IsCycler() { return mIsCycler; }
+  bool IsEditable() { return mIsEditable; }
+  bool IsSelectable() { return mIsSelectable; }
+  bool Overflow() { return mOverflow; }
+
+  int16_t GetType() { return mType; }
+
+  int8_t GetCropStyle() { return mCropStyle; }
+  int32_t GetTextAlignment() { return mTextAlignment; }
+
+  void SetNext(nsTreeColumn* aNext) {
+    NS_ASSERTION(!mNext, "already have a next sibling");
+    mNext = aNext;
+  }
+  void SetPrevious(nsTreeColumn* aPrevious) { mPrevious = aPrevious; }
+
+private:
+  /**
+   * Non-null nsIContent for the associated <treecol> element.
+   */
+  nsCOMPtr<nsIContent> mContent;
+
+  nsTreeColumns* mColumns;
+
+  nsString mId;
+  nsCOMPtr<nsIAtom> mAtom;
+
+  int32_t mIndex;
+
+  bool mIsPrimary;
+  bool mIsCycler;
+  bool mIsEditable;
+  bool mIsSelectable;
+  bool mOverflow;
+
+  int16_t mType;
+
+  int8_t mCropStyle;
+  int8_t mTextAlignment;
+
+  RefPtr<nsTreeColumn> mNext;
+  nsTreeColumn* mPrevious;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsTreeColumn, NS_TREECOLUMN_IMPL_CID)
+
+class nsTreeColumns final : public nsITreeColumns
+                          , public nsWrapperCache
+{
+private:
+  ~nsTreeColumns();
+
+public:
+  explicit nsTreeColumns(nsTreeBodyFrame* aTree);
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(nsTreeColumns)
+  NS_DECL_NSITREECOLUMNS
+
+  nsIContent* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+
+  // WebIDL
+  mozilla::dom::TreeBoxObject* GetTree() const;
+  uint32_t Count();
+  uint32_t Length()
+  {
+    return Count();
+  }
+
+  nsTreeColumn* GetFirstColumn() { EnsureColumns(); return mFirstColumn; }
+  nsTreeColumn* GetLastColumn();
+
+  nsTreeColumn* GetPrimaryColumn();
+  nsTreeColumn* GetSortedColumn();
+  nsTreeColumn* GetKeyColumn();
+
+  nsTreeColumn* GetColumnFor(mozilla::dom::Element* aElement);
+
+  nsTreeColumn* IndexedGetter(uint32_t aIndex, bool& aFound);
+  nsTreeColumn* GetColumnAt(uint32_t aIndex);
+  nsTreeColumn* NamedGetter(const nsAString& aId, bool& aFound);
+  nsTreeColumn* GetNamedColumn(const nsAString& aId);
+  void GetSupportedNames(nsTArray<nsString>& aNames);
+
+  // Uses XPCOM InvalidateColumns().
+  // Uses XPCOM RestoreNaturalOrder().
+
+  friend class nsTreeBodyFrame;
+protected:
+  void SetTree(nsTreeBodyFrame* aTree) { mTree = aTree; }
+
+  // Builds our cache of column info.
+  void EnsureColumns();
+
+private:
+  nsTreeBodyFrame* mTree;
+
+  /**
+   * The first column in the list of columns. All of the columns are supposed
+   * to be "alive", i.e. have a frame. This is achieved by clearing the columns
+   * list each time an nsTreeColFrame is destroyed.
+   *
+   * XXX this means that new nsTreeColumn objects are unnecessarily created
+   *     for untouched columns.
+   */
+  RefPtr<nsTreeColumn> mFirstColumn;
+};
+
+#endif // nsTreeColumns_h__
diff --git a/layout/xul/tree/nsTreeContentView.cpp b/layout/xul/tree/nsTreeContentView.cpp
new file mode 100644
index 0000000000..66cc0072ff
--- /dev/null
+++ b/layout/xul/tree/nsTreeContentView.cpp
@@ -0,0 +1,1372 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsIBoxObject.h"
+#include "nsTreeUtils.h"
+#include "nsTreeContentView.h"
+#include "ChildIterator.h"
+#include "nsDOMClassInfoID.h"
+#include "nsError.h"
+#include "nsIXULSortService.h"
+#include "nsContentUtils.h"
+#include "nsTreeBodyFrame.h"
+#include "mozilla/dom/Element.h"
+#include "nsServiceManagerUtils.h"
+#include "nsIDocument.h"
+
+using namespace mozilla;
+
+#define NS_ENSURE_NATIVE_COLUMN(_col)                                \
+  RefPtr<nsTreeColumn> col = nsTreeBodyFrame::GetColumnImpl(_col); \
+  if (!col) {                                                        \
+    return NS_ERROR_INVALID_ARG;                                     \
+  }
+
+// A content model view implementation for the tree.
+
+#define ROW_FLAG_CONTAINER      0x01
+#define ROW_FLAG_OPEN           0x02
+#define ROW_FLAG_EMPTY          0x04
+#define ROW_FLAG_SEPARATOR      0x08
+
+class Row
+{
+  public:
+    Row(nsIContent* aContent, int32_t aParentIndex)
+      : mContent(aContent), mParentIndex(aParentIndex),
+        mSubtreeSize(0), mFlags(0) {
+    }
+
+    ~Row() {
+    }
+
+    void SetContainer(bool aContainer) {
+      aContainer ? mFlags |= ROW_FLAG_CONTAINER : mFlags &= ~ROW_FLAG_CONTAINER;
+    }
+    bool IsContainer() { return mFlags & ROW_FLAG_CONTAINER; }
+
+    void SetOpen(bool aOpen) {
+      aOpen ? mFlags |= ROW_FLAG_OPEN : mFlags &= ~ROW_FLAG_OPEN;
+    }
+    bool IsOpen() { return !!(mFlags & ROW_FLAG_OPEN); }
+
+    void SetEmpty(bool aEmpty) {
+      aEmpty ? mFlags |= ROW_FLAG_EMPTY : mFlags &= ~ROW_FLAG_EMPTY;
+    }
+    bool IsEmpty() { return !!(mFlags & ROW_FLAG_EMPTY); }
+
+    void SetSeparator(bool aSeparator) {
+      aSeparator ? mFlags |= ROW_FLAG_SEPARATOR : mFlags &= ~ROW_FLAG_SEPARATOR;
+    }
+    bool IsSeparator() { return !!(mFlags & ROW_FLAG_SEPARATOR); }
+
+    // Weak reference to a content item.
+    nsIContent*         mContent;
+
+    // The parent index of the item, set to -1 for the top level items.
+    int32_t             mParentIndex;
+
+    // Subtree size for this item.
+    int32_t             mSubtreeSize;
+
+  private:
+    // State flags
+    int8_t		mFlags;
+};
+
+
+// We don't reference count the reference to the document
+// If the document goes away first, we'll be informed and we
+// can drop our reference.
+// If we go away first, we'll get rid of ourselves from the
+// document's observer list.
+
+nsTreeContentView::nsTreeContentView(void) :
+  mBoxObject(nullptr),
+  mSelection(nullptr),
+  mRoot(nullptr),
+  mDocument(nullptr)
+{
+}
+
+nsTreeContentView::~nsTreeContentView(void)
+{
+  // Remove ourselves from mDocument's observers.
+  if (mDocument)
+    mDocument->RemoveObserver(this);
+}
+
+nsresult
+NS_NewTreeContentView(nsITreeView** aResult)
+{
+  *aResult = new nsTreeContentView;
+  if (! *aResult)
+    return NS_ERROR_OUT_OF_MEMORY;
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+NS_IMPL_CYCLE_COLLECTION(nsTreeContentView,
+                         mBoxObject,
+                         mSelection,
+                         mRoot,
+                         mBody)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsTreeContentView)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsTreeContentView)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsTreeContentView)
+  NS_INTERFACE_MAP_ENTRY(nsITreeView)
+  NS_INTERFACE_MAP_ENTRY(nsITreeContentView)
+  NS_INTERFACE_MAP_ENTRY(nsIDocumentObserver)
+  NS_INTERFACE_MAP_ENTRY(nsIMutationObserver)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsITreeContentView)
+  NS_DOM_INTERFACE_MAP_ENTRY_CLASSINFO(TreeContentView)
+NS_INTERFACE_MAP_END
+
+NS_IMETHODIMP
+nsTreeContentView::GetRowCount(int32_t* aRowCount)
+{
+  *aRowCount = mRows.Length();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetSelection(nsITreeSelection** aSelection)
+{
+  NS_IF_ADDREF(*aSelection = mSelection);
+
+  return NS_OK;
+}
+
+bool
+nsTreeContentView::CanTrustTreeSelection(nsISupports* aValue)
+{
+  // Untrusted content is only allowed to specify known-good views
+  if (nsContentUtils::LegacyIsCallerChromeOrNativeCode())
+    return true;
+  nsCOMPtr<nsINativeTreeSelection> nativeTreeSel = do_QueryInterface(aValue);
+  return nativeTreeSel && NS_SUCCEEDED(nativeTreeSel->EnsureNative());
+}
+
+NS_IMETHODIMP
+nsTreeContentView::SetSelection(nsITreeSelection* aSelection)
+{
+  NS_ENSURE_TRUE(!aSelection || CanTrustTreeSelection(aSelection),
+                 NS_ERROR_DOM_SECURITY_ERR);
+
+  mSelection = aSelection;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetRowProperties(int32_t aIndex, nsAString& aProps)
+{
+  NS_PRECONDITION(aIndex >= 0 && aIndex < int32_t(mRows.Length()), "bad index");
+  if (aIndex < 0 || aIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  Row* row = mRows[aIndex].get();
+  nsIContent* realRow;
+  if (row->IsSeparator())
+    realRow = row->mContent;
+  else
+    realRow = nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+
+  if (realRow) {
+    realRow->GetAttr(kNameSpaceID_None, nsGkAtoms::properties, aProps);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetCellProperties(int32_t aRow, nsITreeColumn* aCol,
+                                     nsAString& aProps)
+{
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  Row* row = mRows[aRow].get();
+  nsIContent* realRow =
+    nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+  if (realRow) {
+    nsIContent* cell = GetCell(realRow, aCol);
+    if (cell) {
+      cell->GetAttr(kNameSpaceID_None, nsGkAtoms::properties, aProps);
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetColumnProperties(nsITreeColumn* aCol, nsAString& aProps)
+{
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  nsCOMPtr<nsIDOMElement> element;
+  aCol->GetElement(getter_AddRefs(element));
+
+  element->GetAttribute(NS_LITERAL_STRING("properties"), aProps);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::IsContainer(int32_t aIndex, bool* _retval)
+{
+  NS_PRECONDITION(aIndex >= 0 && aIndex < int32_t(mRows.Length()), "bad index");
+  if (aIndex < 0 || aIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  *_retval = mRows[aIndex]->IsContainer();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::IsContainerOpen(int32_t aIndex, bool* _retval)
+{
+  NS_PRECONDITION(aIndex >= 0 && aIndex < int32_t(mRows.Length()), "bad index");
+  if (aIndex < 0 || aIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  *_retval = mRows[aIndex]->IsOpen();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::IsContainerEmpty(int32_t aIndex, bool* _retval)
+{
+  NS_PRECONDITION(aIndex >= 0 && aIndex < int32_t(mRows.Length()), "bad index");
+  if (aIndex < 0 || aIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  *_retval = mRows[aIndex]->IsEmpty();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::IsSeparator(int32_t aIndex, bool *_retval)
+{
+  NS_PRECONDITION(aIndex >= 0 && aIndex < int32_t(mRows.Length()), "bad index");
+  if (aIndex < 0 || aIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  *_retval = mRows[aIndex]->IsSeparator();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::IsSorted(bool *_retval)
+{
+  *_retval = false;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::CanDrop(int32_t aIndex, int32_t aOrientation,
+                           nsIDOMDataTransfer* aDataTransfer, bool *_retval)
+{
+  NS_PRECONDITION(aIndex >= 0 && aIndex < int32_t(mRows.Length()), "bad index");
+  if (aIndex < 0 || aIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  *_retval = false;
+ 
+  return NS_OK;
+}
+ 
+NS_IMETHODIMP
+nsTreeContentView::Drop(int32_t aRow, int32_t aOrientation, nsIDOMDataTransfer* aDataTransfer)
+{
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetParentIndex(int32_t aRowIndex, int32_t* _retval)
+{
+  NS_PRECONDITION(aRowIndex >= 0 && aRowIndex < int32_t(mRows.Length()),
+                  "bad row index");
+  if (aRowIndex < 0 || aRowIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  *_retval = mRows[aRowIndex]->mParentIndex;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::HasNextSibling(int32_t aRowIndex, int32_t aAfterIndex, bool* _retval)
+{
+  NS_PRECONDITION(aRowIndex >= 0 && aRowIndex < int32_t(mRows.Length()),
+                  "bad row index");
+  if (aRowIndex < 0 || aRowIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  // We have a next sibling if the row is not the last in the subtree.
+  int32_t parentIndex = mRows[aRowIndex]->mParentIndex;
+  if (parentIndex >= 0) {
+    // Compute the last index in this subtree.
+    int32_t lastIndex = parentIndex + (mRows[parentIndex])->mSubtreeSize;
+    Row* row = mRows[lastIndex].get();
+    while (row->mParentIndex != parentIndex) {
+      lastIndex = row->mParentIndex;
+      row = mRows[lastIndex].get();
+    }
+
+    *_retval = aRowIndex < lastIndex;
+  }
+  else {
+    *_retval = uint32_t(aRowIndex) < mRows.Length() - 1;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetLevel(int32_t aIndex, int32_t* _retval)
+{
+  NS_PRECONDITION(aIndex >= 0 && aIndex < int32_t(mRows.Length()), "bad index");
+  if (aIndex < 0 || aIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  int32_t level = 0;
+  Row* row = mRows[aIndex].get();
+  while (row->mParentIndex >= 0) {
+    level++;
+    row = mRows[row->mParentIndex].get();
+  }
+  *_retval = level;
+
+  return NS_OK;
+}
+
+ NS_IMETHODIMP
+nsTreeContentView::GetImageSrc(int32_t aRow, nsITreeColumn* aCol, nsAString& _retval)
+{
+  _retval.Truncate();
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  Row* row = mRows[aRow].get();
+
+  nsIContent* realRow =
+    nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+  if (realRow) {
+    nsIContent* cell = GetCell(realRow, aCol);
+    if (cell)
+      cell->GetAttr(kNameSpaceID_None, nsGkAtoms::src, _retval);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetProgressMode(int32_t aRow, nsITreeColumn* aCol, int32_t* _retval)
+{
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  *_retval = nsITreeView::PROGRESS_NONE;
+
+  Row* row = mRows[aRow].get();
+
+  nsIContent* realRow =
+    nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+  if (realRow) {
+    nsIContent* cell = GetCell(realRow, aCol);
+    if (cell) {
+      static nsIContent::AttrValuesArray strings[] =
+        {&nsGkAtoms::normal, &nsGkAtoms::undetermined, nullptr};
+      switch (cell->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::mode,
+                                    strings, eCaseMatters)) {
+        case 0: *_retval = nsITreeView::PROGRESS_NORMAL; break;
+        case 1: *_retval = nsITreeView::PROGRESS_UNDETERMINED; break;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetCellValue(int32_t aRow, nsITreeColumn* aCol, nsAString& _retval)
+{
+  _retval.Truncate();
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  Row* row = mRows[aRow].get();
+
+  nsIContent* realRow =
+    nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+  if (realRow) {
+    nsIContent* cell = GetCell(realRow, aCol);
+    if (cell)
+      cell->GetAttr(kNameSpaceID_None, nsGkAtoms::value, _retval);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetCellText(int32_t aRow, nsITreeColumn* aCol, nsAString& _retval)
+{
+  _retval.Truncate();
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  NS_PRECONDITION(aCol, "bad column");
+
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()) || !aCol)
+    return NS_ERROR_INVALID_ARG;
+
+  Row* row = mRows[aRow].get();
+
+  // Check for a "label" attribute - this is valid on an <treeitem>
+  // with a single implied column.
+  if (row->mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::label, _retval)
+      && !_retval.IsEmpty())
+    return NS_OK;
+
+  if (row->mContent->IsXULElement(nsGkAtoms::treeitem)) {
+    nsIContent* realRow =
+      nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+    if (realRow) {
+      nsIContent* cell = GetCell(realRow, aCol);
+      if (cell)
+        cell->GetAttr(kNameSpaceID_None, nsGkAtoms::label, _retval);
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::SetTree(nsITreeBoxObject* aTree)
+{
+  ClearRows();
+
+  mBoxObject = aTree;
+
+  MOZ_ASSERT(!mRoot, "mRoot should have been cleared out by ClearRows");
+
+  if (aTree) {
+    // Get our root element
+    nsCOMPtr<nsIBoxObject> boxObject = do_QueryInterface(mBoxObject);
+    if (!boxObject) {
+      mBoxObject = nullptr;
+      return NS_ERROR_INVALID_ARG;
+    }
+    nsCOMPtr<nsIDOMElement> element;
+    boxObject->GetElement(getter_AddRefs(element));
+
+    mRoot = do_QueryInterface(element);
+    NS_ENSURE_STATE(mRoot);
+
+    // Add ourselves to document's observers.
+    nsIDocument* document = mRoot->GetComposedDoc();
+    if (document) {
+      document->AddObserver(this);
+      mDocument = document;
+    }
+
+    nsCOMPtr<nsIDOMElement> bodyElement;
+    mBoxObject->GetTreeBody(getter_AddRefs(bodyElement));
+    if (bodyElement) {
+      mBody = do_QueryInterface(bodyElement);
+      int32_t index = 0;
+      Serialize(mBody, -1, &index, mRows);
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::ToggleOpenState(int32_t aIndex)
+{
+  NS_PRECONDITION(aIndex >= 0 && aIndex < int32_t(mRows.Length()), "bad index");
+  if (aIndex < 0 || aIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  // We don't serialize content right here, since content might be generated
+  // lazily.
+  Row* row = mRows[aIndex].get();
+
+  if (row->IsOpen())
+    row->mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::open, NS_LITERAL_STRING("false"), true);
+  else
+    row->mContent->SetAttr(kNameSpaceID_None, nsGkAtoms::open, NS_LITERAL_STRING("true"), true);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::CycleHeader(nsITreeColumn* aCol)
+{
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+
+  if (!mRoot)
+    return NS_OK;
+
+  nsCOMPtr<nsIDOMElement> element;
+  aCol->GetElement(getter_AddRefs(element));
+  if (element) {
+    nsCOMPtr<nsIContent> column = do_QueryInterface(element);
+    nsAutoString sort;
+    column->GetAttr(kNameSpaceID_None, nsGkAtoms::sort, sort);
+    if (!sort.IsEmpty()) {
+      nsCOMPtr<nsIXULSortService> xs = do_GetService("@mozilla.org/xul/xul-sort-service;1");
+      if (xs) {
+        nsAutoString sortdirection;
+        static nsIContent::AttrValuesArray strings[] =
+          {&nsGkAtoms::ascending, &nsGkAtoms::descending, nullptr};
+        switch (column->FindAttrValueIn(kNameSpaceID_None,
+                                        nsGkAtoms::sortDirection,
+                                        strings, eCaseMatters)) {
+          case 0: sortdirection.AssignLiteral("descending"); break;
+          case 1: sortdirection.AssignLiteral("natural"); break;
+          default: sortdirection.AssignLiteral("ascending"); break;
+        }
+
+        nsAutoString hints;
+        column->GetAttr(kNameSpaceID_None, nsGkAtoms::sorthints, hints);
+        sortdirection.Append(' ');
+        sortdirection += hints;
+
+        nsCOMPtr<nsIDOMNode> rootnode = do_QueryInterface(mRoot);
+        xs->Sort(rootnode, sort, sortdirection);
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::SelectionChanged()
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::CycleCell(int32_t aRow, nsITreeColumn* aCol)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::IsEditable(int32_t aRow, nsITreeColumn* aCol, bool* _retval)
+{
+  *_retval = false;
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  *_retval = true;
+
+  Row* row = mRows[aRow].get();
+
+  nsIContent* realRow =
+    nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+  if (realRow) {
+    nsIContent* cell = GetCell(realRow, aCol);
+    if (cell && cell->AttrValueIs(kNameSpaceID_None, nsGkAtoms::editable,
+                                  nsGkAtoms::_false, eCaseMatters)) {
+      *_retval = false;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::IsSelectable(int32_t aRow, nsITreeColumn* aCol, bool* _retval)
+{
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  *_retval = true;
+
+  Row* row = mRows[aRow].get();
+
+  nsIContent* realRow =
+    nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+  if (realRow) {
+    nsIContent* cell = GetCell(realRow, aCol);
+    if (cell && cell->AttrValueIs(kNameSpaceID_None, nsGkAtoms::selectable,
+                                  nsGkAtoms::_false, eCaseMatters)) {
+      *_retval = false;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::SetCellValue(int32_t aRow, nsITreeColumn* aCol, const nsAString& aValue)
+{
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  Row* row = mRows[aRow].get();
+
+  nsIContent* realRow =
+    nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+  if (realRow) {
+    nsIContent* cell = GetCell(realRow, aCol);
+    if (cell)
+      cell->SetAttr(kNameSpaceID_None, nsGkAtoms::value, aValue, true);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::SetCellText(int32_t aRow, nsITreeColumn* aCol, const nsAString& aValue)
+{
+  NS_ENSURE_NATIVE_COLUMN(aCol);
+  NS_PRECONDITION(aRow >= 0 && aRow < int32_t(mRows.Length()), "bad row");
+  if (aRow < 0 || aRow >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  Row* row = mRows[aRow].get();
+
+  nsIContent* realRow =
+    nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treerow);
+  if (realRow) {
+    nsIContent* cell = GetCell(realRow, aCol);
+    if (cell)
+      cell->SetAttr(kNameSpaceID_None, nsGkAtoms::label, aValue, true);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::PerformAction(const char16_t* aAction)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::PerformActionOnRow(const char16_t* aAction, int32_t aRow)
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::PerformActionOnCell(const char16_t* aAction, int32_t aRow, nsITreeColumn* aCol)
+{
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP
+nsTreeContentView::GetItemAtIndex(int32_t aIndex, nsIDOMElement** _retval)
+{
+  NS_PRECONDITION(aIndex >= 0 && aIndex < int32_t(mRows.Length()), "bad index");
+  if (aIndex < 0 || aIndex >= int32_t(mRows.Length()))
+    return NS_ERROR_INVALID_ARG;   
+
+  Row* row = mRows[aIndex].get();
+  row->mContent->QueryInterface(NS_GET_IID(nsIDOMElement), (void**)_retval);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeContentView::GetIndexOfItem(nsIDOMElement* aItem, int32_t* _retval)
+{
+  nsCOMPtr<nsIContent> content = do_QueryInterface(aItem);
+  *_retval = FindContent(content);
+
+  return NS_OK;
+}
+
+void
+nsTreeContentView::AttributeChanged(nsIDocument*  aDocument,
+                                    dom::Element* aElement,
+                                    int32_t       aNameSpaceID,
+                                    nsIAtom*      aAttribute,
+                                    int32_t       aModType,
+                                    const nsAttrValue* aOldValue)
+{
+  // Lots of codepaths under here that do all sorts of stuff, so be safe.
+  nsCOMPtr<nsIMutationObserver> kungFuDeathGrip(this);
+
+  // Make sure this notification concerns us.
+  // First check the tag to see if it's one that we care about.
+
+  if (mBoxObject && (aElement == mRoot || aElement == mBody)) {
+    mBoxObject->ClearStyleAndImageCaches();
+    mBoxObject->Invalidate();
+  }
+
+  // We don't consider non-XUL nodes.
+  nsIContent* parent = nullptr;
+  if (!aElement->IsXULElement() ||
+      ((parent = aElement->GetParent()) && !parent->IsXULElement())) {
+    return;
+  }
+  if (!aElement->IsAnyOfXULElements(nsGkAtoms::treecol,
+                                    nsGkAtoms::treeitem,
+                                    nsGkAtoms::treeseparator,
+                                    nsGkAtoms::treerow,
+                                    nsGkAtoms::treecell)) {
+    return;
+  }
+
+  // If we have a legal tag, go up to the tree/select and make sure
+  // that it's ours.
+
+  for (nsIContent* element = aElement; element != mBody; element = element->GetParent()) {
+    if (!element)
+      return; // this is not for us
+    if (element->IsXULElement(nsGkAtoms::tree))
+      return; // this is not for us
+  }
+
+  // Handle changes of the hidden attribute.
+  if (aAttribute == nsGkAtoms::hidden &&
+      aElement->IsAnyOfXULElements(nsGkAtoms::treeitem,
+                                   nsGkAtoms::treeseparator)) {
+    bool hidden = aElement->AttrValueIs(kNameSpaceID_None,
+                                          nsGkAtoms::hidden,
+                                          nsGkAtoms::_true, eCaseMatters);
+ 
+    int32_t index = FindContent(aElement);
+    if (hidden && index >= 0) {
+      // Hide this row along with its children.
+      int32_t count = RemoveRow(index);
+      if (mBoxObject)
+        mBoxObject->RowCountChanged(index, -count);
+    }
+    else if (!hidden && index < 0) {
+      // Show this row along with its children.
+      nsCOMPtr<nsIContent> parent = aElement->GetParent();
+      if (parent) {
+        InsertRowFor(parent, aElement);
+      }
+    }
+
+    return;
+  }
+
+  if (aElement->IsXULElement(nsGkAtoms::treecol)) {
+    if (aAttribute == nsGkAtoms::properties) {
+      if (mBoxObject) {
+        nsCOMPtr<nsITreeColumns> cols;
+        mBoxObject->GetColumns(getter_AddRefs(cols));
+        if (cols) {
+          nsCOMPtr<nsIDOMElement> element = do_QueryInterface(aElement);
+          nsCOMPtr<nsITreeColumn> col;
+          cols->GetColumnFor(element, getter_AddRefs(col));
+          mBoxObject->InvalidateColumn(col);
+        }
+      }
+    }
+  }
+  else if (aElement->IsXULElement(nsGkAtoms::treeitem)) {
+    int32_t index = FindContent(aElement);
+    if (index >= 0) {
+      Row* row = mRows[index].get();
+      if (aAttribute == nsGkAtoms::container) {
+        bool isContainer =
+          aElement->AttrValueIs(kNameSpaceID_None, nsGkAtoms::container,
+                                nsGkAtoms::_true, eCaseMatters);
+        row->SetContainer(isContainer);
+        if (mBoxObject)
+          mBoxObject->InvalidateRow(index);
+      }
+      else if (aAttribute == nsGkAtoms::open) {
+        bool isOpen =
+          aElement->AttrValueIs(kNameSpaceID_None, nsGkAtoms::open,
+                                nsGkAtoms::_true, eCaseMatters);
+        bool wasOpen = row->IsOpen();
+        if (! isOpen && wasOpen)
+          CloseContainer(index);
+        else if (isOpen && ! wasOpen)
+          OpenContainer(index);
+      }
+      else if (aAttribute == nsGkAtoms::empty) {
+        bool isEmpty =
+          aElement->AttrValueIs(kNameSpaceID_None, nsGkAtoms::empty,
+                                nsGkAtoms::_true, eCaseMatters);
+        row->SetEmpty(isEmpty);
+        if (mBoxObject)
+          mBoxObject->InvalidateRow(index);
+      }
+    }
+  }
+  else if (aElement->IsXULElement(nsGkAtoms::treeseparator)) {
+    int32_t index = FindContent(aElement);
+    if (index >= 0) {
+      if (aAttribute == nsGkAtoms::properties && mBoxObject) {
+        mBoxObject->InvalidateRow(index);
+      }
+    }
+  }
+  else if (aElement->IsXULElement(nsGkAtoms::treerow)) {
+    if (aAttribute == nsGkAtoms::properties) {
+      nsCOMPtr<nsIContent> parent = aElement->GetParent();
+      if (parent) {
+        int32_t index = FindContent(parent);
+        if (index >= 0 && mBoxObject) {
+          mBoxObject->InvalidateRow(index);
+        }
+      }
+    }
+  }
+  else if (aElement->IsXULElement(nsGkAtoms::treecell)) {
+    if (aAttribute == nsGkAtoms::ref ||
+        aAttribute == nsGkAtoms::properties ||
+        aAttribute == nsGkAtoms::mode ||
+        aAttribute == nsGkAtoms::src ||
+        aAttribute == nsGkAtoms::value ||
+        aAttribute == nsGkAtoms::label) {
+      nsIContent* parent = aElement->GetParent();
+      if (parent) {
+        nsCOMPtr<nsIContent> grandParent = parent->GetParent();
+        if (grandParent && grandParent->IsXULElement()) {
+          int32_t index = FindContent(grandParent);
+          if (index >= 0 && mBoxObject) {
+            // XXX Should we make an effort to invalidate only cell ?
+            mBoxObject->InvalidateRow(index);
+          }
+        }
+      }
+    }
+  }
+}
+
+void
+nsTreeContentView::ContentAppended(nsIDocument *aDocument,
+                                   nsIContent* aContainer,
+                                   nsIContent* aFirstNewContent,
+                                   int32_t     /* unused */)
+{
+  for (nsIContent* cur = aFirstNewContent; cur; cur = cur->GetNextSibling()) {
+    // Our contentinserted doesn't use the index
+    ContentInserted(aDocument, aContainer, cur, 0);
+  }
+}
+
+void
+nsTreeContentView::ContentInserted(nsIDocument *aDocument,
+                                   nsIContent* aContainer,
+                                   nsIContent* aChild,
+                                   int32_t /* unused */)
+{
+  NS_ASSERTION(aChild, "null ptr");
+
+  // Make sure this notification concerns us.
+  // First check the tag to see if it's one that we care about.
+
+  // Don't allow non-XUL nodes.
+  if (!aChild->IsXULElement() || !aContainer->IsXULElement())
+    return;
+
+  if (!aChild->IsAnyOfXULElements(nsGkAtoms::treeitem,
+                                  nsGkAtoms::treeseparator,
+                                  nsGkAtoms::treechildren,
+                                  nsGkAtoms::treerow,
+                                  nsGkAtoms::treecell)) {
+    return;
+  }
+
+  // If we have a legal tag, go up to the tree/select and make sure
+  // that it's ours.
+
+  for (nsIContent* element = aContainer; element != mBody; element = element->GetParent()) {
+    if (!element)
+      return; // this is not for us
+    if (element->IsXULElement(nsGkAtoms::tree))
+      return; // this is not for us
+  }
+
+  // Lots of codepaths under here that do all sorts of stuff, so be safe.
+  nsCOMPtr<nsIMutationObserver> kungFuDeathGrip(this);
+
+  if (aChild->IsXULElement(nsGkAtoms::treechildren)) {
+    int32_t index = FindContent(aContainer);
+    if (index >= 0) {
+      Row* row = mRows[index].get();
+      row->SetEmpty(false);
+      if (mBoxObject)
+        mBoxObject->InvalidateRow(index);
+      if (row->IsContainer() && row->IsOpen()) {
+        int32_t count = EnsureSubtree(index);
+        if (mBoxObject)
+          mBoxObject->RowCountChanged(index + 1, count);
+      }
+    }
+  }
+  else if (aChild->IsAnyOfXULElements(nsGkAtoms::treeitem,
+                                      nsGkAtoms::treeseparator)) {
+    InsertRowFor(aContainer, aChild);
+  }
+  else if (aChild->IsXULElement(nsGkAtoms::treerow)) {
+    int32_t index = FindContent(aContainer);
+    if (index >= 0 && mBoxObject)
+      mBoxObject->InvalidateRow(index);
+  }
+  else if (aChild->IsXULElement(nsGkAtoms::treecell)) {
+    nsCOMPtr<nsIContent> parent = aContainer->GetParent();
+    if (parent) {
+      int32_t index = FindContent(parent);
+      if (index >= 0 && mBoxObject)
+        mBoxObject->InvalidateRow(index);
+    }
+  }
+}
+
+void
+nsTreeContentView::ContentRemoved(nsIDocument *aDocument,
+                                  nsIContent* aContainer,
+                                  nsIContent* aChild,
+                                  int32_t aIndexInContainer,
+                                  nsIContent* aPreviousSibling)
+{
+  NS_ASSERTION(aChild, "null ptr");
+
+  // Make sure this notification concerns us.
+  // First check the tag to see if it's one that we care about.
+
+  // We don't consider non-XUL nodes.
+  if (!aChild->IsXULElement() || !aContainer->IsXULElement())
+    return;
+
+  if (!aChild->IsAnyOfXULElements(nsGkAtoms::treeitem,
+                                  nsGkAtoms::treeseparator,
+                                  nsGkAtoms::treechildren,
+                                  nsGkAtoms::treerow,
+                                  nsGkAtoms::treecell)) {
+    return;
+  }
+
+  // If we have a legal tag, go up to the tree/select and make sure
+  // that it's ours.
+
+  for (nsIContent* element = aContainer; element != mBody; element = element->GetParent()) {
+    if (!element)
+      return; // this is not for us
+    if (element->IsXULElement(nsGkAtoms::tree))
+      return; // this is not for us
+  }
+
+  // Lots of codepaths under here that do all sorts of stuff, so be safe.
+  nsCOMPtr<nsIMutationObserver> kungFuDeathGrip(this);
+
+  if (aChild->IsXULElement(nsGkAtoms::treechildren)) {
+    int32_t index = FindContent(aContainer);
+    if (index >= 0) {
+      Row* row = mRows[index].get();
+      row->SetEmpty(true);
+      int32_t count = RemoveSubtree(index);
+      // Invalidate also the row to update twisty.
+      if (mBoxObject) {
+        mBoxObject->InvalidateRow(index);
+        mBoxObject->RowCountChanged(index + 1, -count);
+      }
+    }
+  }
+  else if (aChild->IsAnyOfXULElements(nsGkAtoms::treeitem,
+                                      nsGkAtoms::treeseparator)) {
+    int32_t index = FindContent(aChild);
+    if (index >= 0) {
+      int32_t count = RemoveRow(index);
+      if (mBoxObject)
+        mBoxObject->RowCountChanged(index, -count);
+    }
+  }
+  else if (aChild->IsXULElement(nsGkAtoms::treerow)) {
+    int32_t index = FindContent(aContainer);
+    if (index >= 0 && mBoxObject)
+      mBoxObject->InvalidateRow(index);
+  }
+  else if (aChild->IsXULElement(nsGkAtoms::treecell)) {
+    nsCOMPtr<nsIContent> parent = aContainer->GetParent();
+    if (parent) {
+      int32_t index = FindContent(parent);
+      if (index >= 0 && mBoxObject)
+        mBoxObject->InvalidateRow(index);
+    }
+  }
+}
+
+void
+nsTreeContentView::NodeWillBeDestroyed(const nsINode* aNode)
+{
+  // XXXbz do we need this strong ref?  Do we drop refs to self in ClearRows?
+  nsCOMPtr<nsIMutationObserver> kungFuDeathGrip(this);
+  ClearRows();
+}
+
+
+// Recursively serialize content, starting with aContent.
+void
+nsTreeContentView::Serialize(nsIContent* aContent, int32_t aParentIndex,
+                             int32_t* aIndex, nsTArray<UniquePtr<Row>>& aRows)
+{
+  // Don't allow non-XUL nodes.
+  if (!aContent->IsXULElement())
+    return;
+
+  dom::FlattenedChildIterator iter(aContent);
+  for (nsIContent* content = iter.GetNextChild(); content; content = iter.GetNextChild()) {
+    int32_t count = aRows.Length();
+
+    if (content->IsXULElement(nsGkAtoms::treeitem)) {
+      SerializeItem(content, aParentIndex, aIndex, aRows);
+    } else if (content->IsXULElement(nsGkAtoms::treeseparator)) {
+      SerializeSeparator(content, aParentIndex, aIndex, aRows);
+    }
+
+    *aIndex += aRows.Length() - count;
+  }
+}
+
+void
+nsTreeContentView::SerializeItem(nsIContent* aContent, int32_t aParentIndex,
+                                 int32_t* aIndex, nsTArray<UniquePtr<Row>>& aRows)
+{
+  if (aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::hidden,
+                            nsGkAtoms::_true, eCaseMatters))
+    return;
+
+  aRows.AppendElement(MakeUnique<Row>(aContent, aParentIndex));
+  Row* row = aRows.LastElement().get();
+
+  if (aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::container,
+                            nsGkAtoms::_true, eCaseMatters)) {
+    row->SetContainer(true);
+    if (aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::open,
+                              nsGkAtoms::_true, eCaseMatters)) {
+      row->SetOpen(true);
+      nsIContent* child =
+        nsTreeUtils::GetImmediateChild(aContent, nsGkAtoms::treechildren);
+      if (child && child->IsXULElement()) {
+        // Now, recursively serialize our child.
+        int32_t count = aRows.Length();
+        int32_t index = 0;
+        Serialize(child, aParentIndex + *aIndex + 1, &index, aRows);
+        row->mSubtreeSize += aRows.Length() - count;
+      }
+      else
+        row->SetEmpty(true);
+    } else if (aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::empty,
+                                     nsGkAtoms::_true, eCaseMatters)) {
+      row->SetEmpty(true);
+    }
+  } 
+}
+
+void
+nsTreeContentView::SerializeSeparator(nsIContent* aContent,
+                                      int32_t aParentIndex, int32_t* aIndex,
+                                      nsTArray<UniquePtr<Row>>& aRows)
+{
+  if (aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::hidden,
+                            nsGkAtoms::_true, eCaseMatters))
+    return;
+
+  auto row = MakeUnique<Row>(aContent, aParentIndex);
+  row->SetSeparator(true);
+  aRows.AppendElement(Move(row));
+}
+
+void
+nsTreeContentView::GetIndexInSubtree(nsIContent* aContainer,
+                                     nsIContent* aContent, int32_t* aIndex)
+{
+  uint32_t childCount = aContainer->GetChildCount();
+  
+  if (!aContainer->IsXULElement())
+    return;
+
+  for (uint32_t i = 0; i < childCount; i++) {
+    nsIContent *content = aContainer->GetChildAt(i);
+
+    if (content == aContent)
+      break;
+
+    if (content->IsXULElement(nsGkAtoms::treeitem)) {
+      if (! content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::hidden,
+                                 nsGkAtoms::_true, eCaseMatters)) {
+        (*aIndex)++;
+        if (content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::container,
+                                 nsGkAtoms::_true, eCaseMatters) &&
+            content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::open,
+                                 nsGkAtoms::_true, eCaseMatters)) {
+          nsIContent* child =
+            nsTreeUtils::GetImmediateChild(content, nsGkAtoms::treechildren);
+          if (child && child->IsXULElement())
+            GetIndexInSubtree(child, aContent, aIndex);
+        }
+      }
+    }
+    else if (content->IsXULElement(nsGkAtoms::treeseparator)) {
+      if (! content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::hidden,
+                                 nsGkAtoms::_true, eCaseMatters))
+        (*aIndex)++;
+    }
+  }
+}
+
+int32_t
+nsTreeContentView::EnsureSubtree(int32_t aIndex)
+{
+  Row* row = mRows[aIndex].get();
+
+  nsIContent* child;
+  child = nsTreeUtils::GetImmediateChild(row->mContent, nsGkAtoms::treechildren);
+  if (!child || !child->IsXULElement()) {
+    return 0;
+  }
+
+  AutoTArray<UniquePtr<Row>, 8> rows;
+  int32_t index = 0;
+  Serialize(child, aIndex, &index, rows);
+  // Insert |rows| into |mRows| at position |aIndex|, by first creating empty
+  // UniquePtr entries and then Move'ing |rows|'s entries into them. (Note
+  // that we can't simply use InsertElementsAt with an array argument, since
+  // the destination can't steal ownership from its const source argument.)
+  UniquePtr<Row>* newRows = mRows.InsertElementsAt(aIndex + 1,
+                                                   rows.Length());
+  for (nsTArray<Row>::index_type i = 0; i < rows.Length(); i++) {
+    newRows[i] = Move(rows[i]);
+  }
+  int32_t count = rows.Length();
+
+  row->mSubtreeSize += count;
+  UpdateSubtreeSizes(row->mParentIndex, count);
+
+  // Update parent indexes, but skip newly added rows.
+  // They already have correct values.
+  UpdateParentIndexes(aIndex, count + 1, count);
+
+  return count;
+}
+
+int32_t
+nsTreeContentView::RemoveSubtree(int32_t aIndex)
+{
+  Row* row = mRows[aIndex].get();
+  int32_t count = row->mSubtreeSize;
+
+  mRows.RemoveElementsAt(aIndex + 1, count);
+
+  row->mSubtreeSize -= count;
+  UpdateSubtreeSizes(row->mParentIndex, -count);
+
+  UpdateParentIndexes(aIndex, 0, -count);
+
+  return count;
+}
+
+void
+nsTreeContentView::InsertRowFor(nsIContent* aParent, nsIContent* aChild)
+{
+  int32_t grandParentIndex = -1;
+  bool insertRow = false;
+
+  nsCOMPtr<nsIContent> grandParent = aParent->GetParent();
+
+  if (grandParent->IsXULElement(nsGkAtoms::tree)) {
+    // Allow insertion to the outermost container.
+    insertRow = true;
+  }
+  else {
+    // Test insertion to an inner container.
+
+    // First try to find this parent in our array of rows, if we find one
+    // we can be sure that all other parents are open too.
+    grandParentIndex = FindContent(grandParent);
+    if (grandParentIndex >= 0) {
+      // Got it, now test if it is open.
+      if (mRows[grandParentIndex]->IsOpen())
+        insertRow = true;
+    }
+  }
+
+  if (insertRow) {
+    int32_t index = 0;
+    GetIndexInSubtree(aParent, aChild, &index);
+
+    int32_t count = InsertRow(grandParentIndex, index, aChild);
+    if (mBoxObject)
+      mBoxObject->RowCountChanged(grandParentIndex + index + 1, count);
+  }
+}
+
+int32_t
+nsTreeContentView::InsertRow(int32_t aParentIndex, int32_t aIndex, nsIContent* aContent)
+{
+  AutoTArray<UniquePtr<Row>, 8> rows;
+  if (aContent->IsXULElement(nsGkAtoms::treeitem)) {
+    SerializeItem(aContent, aParentIndex, &aIndex, rows);
+  } else if (aContent->IsXULElement(nsGkAtoms::treeseparator)) {
+    SerializeSeparator(aContent, aParentIndex, &aIndex, rows);
+  }
+
+  // We can't use InsertElementsAt since the destination can't steal
+  // ownership from its const source argument.
+  int32_t count = rows.Length();
+  for (nsTArray<Row>::index_type i = 0; i < size_t(count); i++) {
+    mRows.InsertElementAt(aParentIndex + aIndex + i + 1, Move(rows[i]));
+  }
+
+  UpdateSubtreeSizes(aParentIndex, count);
+
+  // Update parent indexes, but skip added rows.
+  // They already have correct values.
+  UpdateParentIndexes(aParentIndex + aIndex, count + 1, count);
+
+  return count;
+}
+
+int32_t
+nsTreeContentView::RemoveRow(int32_t aIndex)
+{
+  Row* row = mRows[aIndex].get();
+  int32_t count = row->mSubtreeSize + 1;
+  int32_t parentIndex = row->mParentIndex;
+
+  mRows.RemoveElementsAt(aIndex, count);
+
+  UpdateSubtreeSizes(parentIndex, -count);
+
+  UpdateParentIndexes(aIndex, 0, -count);
+
+  return count;
+}
+
+void
+nsTreeContentView::ClearRows()
+{
+  mRows.Clear();
+  mRoot = nullptr;
+  mBody = nullptr;
+  // Remove ourselves from mDocument's observers.
+  if (mDocument) {
+    mDocument->RemoveObserver(this);
+    mDocument = nullptr;
+  }
+}
+
+void
+nsTreeContentView::OpenContainer(int32_t aIndex)
+{
+  Row* row = mRows[aIndex].get();
+  row->SetOpen(true);
+
+  int32_t count = EnsureSubtree(aIndex);
+  if (mBoxObject) {
+    mBoxObject->InvalidateRow(aIndex);
+    mBoxObject->RowCountChanged(aIndex + 1, count);
+  }
+}
+
+void
+nsTreeContentView::CloseContainer(int32_t aIndex)
+{
+  Row* row = mRows[aIndex].get();
+  row->SetOpen(false);
+
+  int32_t count = RemoveSubtree(aIndex);
+  if (mBoxObject) {
+    mBoxObject->InvalidateRow(aIndex);
+    mBoxObject->RowCountChanged(aIndex + 1, -count);
+  }
+}
+
+int32_t
+nsTreeContentView::FindContent(nsIContent* aContent)
+{
+  for (uint32_t i = 0; i < mRows.Length(); i++) {
+    if (mRows[i]->mContent == aContent) {
+      return i;
+    }
+  }
+
+  return -1;
+}
+
+void
+nsTreeContentView::UpdateSubtreeSizes(int32_t aParentIndex, int32_t count)
+{
+  while (aParentIndex >= 0) {
+    Row* row = mRows[aParentIndex].get();
+    row->mSubtreeSize += count;
+    aParentIndex = row->mParentIndex;
+  }
+}
+
+void
+nsTreeContentView::UpdateParentIndexes(int32_t aIndex, int32_t aSkip, int32_t aCount)
+{
+  int32_t count = mRows.Length();
+  for (int32_t i = aIndex + aSkip; i < count; i++) {
+    Row* row = mRows[i].get();
+    if (row->mParentIndex > aIndex) {
+      row->mParentIndex += aCount;
+    }
+  }
+}
+
+nsIContent*
+nsTreeContentView::GetCell(nsIContent* aContainer, nsITreeColumn* aCol)
+{
+  nsCOMPtr<nsIAtom> colAtom;
+  int32_t colIndex;
+  aCol->GetAtom(getter_AddRefs(colAtom));
+  aCol->GetIndex(&colIndex);
+
+  // Traverse through cells, try to find the cell by "ref" attribute or by cell
+  // index in a row. "ref" attribute has higher priority.
+  nsIContent* result = nullptr;
+  int32_t j = 0;
+  dom::FlattenedChildIterator iter(aContainer);
+  for (nsIContent* cell = iter.GetNextChild(); cell; cell = iter.GetNextChild()) {
+    if (cell->IsXULElement(nsGkAtoms::treecell)) {
+      if (colAtom && cell->AttrValueIs(kNameSpaceID_None, nsGkAtoms::ref,
+                                       colAtom, eCaseMatters)) {
+        result = cell;
+        break;
+      }
+      else if (j == colIndex) {
+        result = cell;
+      }
+      j++;
+    }
+  }
+
+  return result;
+}
diff --git a/layout/xul/tree/nsTreeContentView.h b/layout/xul/tree/nsTreeContentView.h
new file mode 100644
index 0000000000..c2c3f50300
--- /dev/null
+++ b/layout/xul/tree/nsTreeContentView.h
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTreeContentView_h__
+#define nsTreeContentView_h__
+
+#include "nsCycleCollectionParticipant.h"
+#include "nsTArray.h"
+#include "nsStubDocumentObserver.h"
+#include "nsITreeBoxObject.h"
+#include "nsITreeColumns.h"
+#include "nsITreeView.h"
+#include "nsITreeContentView.h"
+#include "nsITreeSelection.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/UniquePtr.h"
+
+class nsIDocument;
+class Row;
+
+nsresult NS_NewTreeContentView(nsITreeView** aResult);
+
+class nsTreeContentView final : public nsINativeTreeView,
+                                public nsITreeContentView,
+                                public nsStubDocumentObserver
+{
+  public:
+    nsTreeContentView(void);
+
+    NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+    NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsTreeContentView,
+                                             nsINativeTreeView)
+
+    NS_DECL_NSITREEVIEW
+    // nsINativeTreeView: Untrusted code can use us
+    NS_IMETHOD EnsureNative() override { return NS_OK; }
+
+    NS_DECL_NSITREECONTENTVIEW
+
+    // nsIDocumentObserver
+    NS_DECL_NSIMUTATIONOBSERVER_ATTRIBUTECHANGED
+    NS_DECL_NSIMUTATIONOBSERVER_CONTENTAPPENDED
+    NS_DECL_NSIMUTATIONOBSERVER_CONTENTINSERTED
+    NS_DECL_NSIMUTATIONOBSERVER_CONTENTREMOVED
+    NS_DECL_NSIMUTATIONOBSERVER_NODEWILLBEDESTROYED
+
+    static bool CanTrustTreeSelection(nsISupports* aValue);
+
+  protected:
+    ~nsTreeContentView(void);
+
+    // Recursive methods which deal with serializing of nested content.
+    void Serialize(nsIContent* aContent, int32_t aParentIndex, int32_t* aIndex,
+                   nsTArray<mozilla::UniquePtr<Row>>& aRows);
+
+    void SerializeItem(nsIContent* aContent, int32_t aParentIndex,
+                       int32_t* aIndex, nsTArray<mozilla::UniquePtr<Row>>& aRows);
+
+    void SerializeSeparator(nsIContent* aContent, int32_t aParentIndex,
+                            int32_t* aIndex, nsTArray<mozilla::UniquePtr<Row>>& aRows);
+
+    void GetIndexInSubtree(nsIContent* aContainer, nsIContent* aContent, int32_t* aResult);
+    
+    // Helper methods which we use to manage our plain array of rows.
+    int32_t EnsureSubtree(int32_t aIndex);
+
+    int32_t RemoveSubtree(int32_t aIndex);
+
+    int32_t InsertRow(int32_t aParentIndex, int32_t aIndex, nsIContent* aContent);
+
+    void InsertRowFor(nsIContent* aParent, nsIContent* aChild);
+
+    int32_t RemoveRow(int32_t aIndex);
+
+    void ClearRows();
+    
+    void OpenContainer(int32_t aIndex);
+
+    void CloseContainer(int32_t aIndex);
+
+    int32_t FindContent(nsIContent* aContent);
+
+    void UpdateSubtreeSizes(int32_t aIndex, int32_t aCount);
+
+    void UpdateParentIndexes(int32_t aIndex, int32_t aSkip, int32_t aCount);
+
+    // Content helpers.
+    nsIContent* GetCell(nsIContent* aContainer, nsITreeColumn* aCol);
+
+  private:
+    nsCOMPtr<nsITreeBoxObject>          mBoxObject;
+    nsCOMPtr<nsITreeSelection>          mSelection;
+    nsCOMPtr<nsIContent>                mRoot;
+    nsCOMPtr<nsIContent>                mBody;
+    nsIDocument*                        mDocument;      // WEAK
+    nsTArray<mozilla::UniquePtr<Row>>   mRows;
+};
+
+#endif // nsTreeContentView_h__
diff --git a/layout/xul/tree/nsTreeImageListener.cpp b/layout/xul/tree/nsTreeImageListener.cpp
new file mode 100644
index 0000000000..f559be0423
--- /dev/null
+++ b/layout/xul/tree/nsTreeImageListener.cpp
@@ -0,0 +1,115 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTreeImageListener.h"
+#include "nsITreeBoxObject.h"
+#include "imgIRequest.h"
+#include "imgIContainer.h"
+#include "nsIContent.h"
+
+NS_IMPL_ISUPPORTS(nsTreeImageListener, imgINotificationObserver)
+
+nsTreeImageListener::nsTreeImageListener(nsTreeBodyFrame* aTreeFrame)
+  : mTreeFrame(aTreeFrame),
+    mInvalidationSuppressed(true),
+    mInvalidationArea(nullptr)
+{
+}
+
+nsTreeImageListener::~nsTreeImageListener()
+{
+  delete mInvalidationArea;
+}
+
+NS_IMETHODIMP
+nsTreeImageListener::Notify(imgIRequest *aRequest, int32_t aType, const nsIntRect* aData)
+{
+  if (aType == imgINotificationObserver::IS_ANIMATED) {
+    return mTreeFrame ? mTreeFrame->OnImageIsAnimated(aRequest) : NS_OK;
+  }
+
+  if (aType == imgINotificationObserver::SIZE_AVAILABLE) {
+    // Ensure the animation (if any) is started. Note: There is no
+    // corresponding call to Decrement for this. This Increment will be
+    // 'cleaned up' by the Request when it is destroyed, but only then.
+    aRequest->IncrementAnimationConsumers();
+  }
+
+  if (aType == imgINotificationObserver::FRAME_UPDATE) {
+    Invalidate();
+  }
+
+  return NS_OK;
+}
+
+void
+nsTreeImageListener::AddCell(int32_t aIndex, nsITreeColumn* aCol)
+{
+  if (!mInvalidationArea) {
+    mInvalidationArea = new InvalidationArea(aCol);
+    mInvalidationArea->AddRow(aIndex);
+  }
+  else {
+    InvalidationArea* currArea;
+    for (currArea = mInvalidationArea; currArea; currArea = currArea->GetNext()) {
+      if (currArea->GetCol() == aCol) {
+        currArea->AddRow(aIndex);
+        break;
+      }
+    }
+    if (!currArea) {
+      currArea = new InvalidationArea(aCol);
+      currArea->SetNext(mInvalidationArea);
+      mInvalidationArea = currArea;
+      mInvalidationArea->AddRow(aIndex);
+    }
+  }
+}
+
+
+void
+nsTreeImageListener::Invalidate()
+{
+  if (!mInvalidationSuppressed) {
+    for (InvalidationArea* currArea = mInvalidationArea; currArea;
+         currArea = currArea->GetNext()) {
+      // Loop from min to max, invalidating each cell that was listening for this image.
+      for (int32_t i = currArea->GetMin(); i <= currArea->GetMax(); ++i) {
+        if (mTreeFrame) {
+          nsITreeBoxObject* tree = mTreeFrame->GetTreeBoxObject();
+          if (tree) {
+            tree->InvalidateCell(i, currArea->GetCol());
+          }
+        }
+      }
+    }
+  }
+}
+
+nsTreeImageListener::InvalidationArea::InvalidationArea(nsITreeColumn* aCol)
+  : mCol(aCol),
+    mMin(-1), // min should start out "undefined"
+    mMax(0),
+    mNext(nullptr)
+{
+}
+
+void
+nsTreeImageListener::InvalidationArea::AddRow(int32_t aIndex)
+{
+  if (mMin == -1)
+    mMin = mMax = aIndex;
+  else if (aIndex < mMin)
+    mMin = aIndex;
+  else if (aIndex > mMax)
+    mMax = aIndex;
+}
+
+NS_IMETHODIMP
+nsTreeImageListener::ClearFrame()
+{
+  mTreeFrame = nullptr;
+  return NS_OK;
+}
diff --git a/layout/xul/tree/nsTreeImageListener.h b/layout/xul/tree/nsTreeImageListener.h
new file mode 100644
index 0000000000..573b246e58
--- /dev/null
+++ b/layout/xul/tree/nsTreeImageListener.h
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTreeImageListener_h__
+#define nsTreeImageListener_h__
+
+#include "nsString.h"
+#include "nsCOMPtr.h"
+#include "nsITreeColumns.h"
+#include "nsTreeBodyFrame.h"
+#include "mozilla/Attributes.h"
+
+// This class handles image load observation.
+class nsTreeImageListener final : public imgINotificationObserver
+{
+public:
+  explicit nsTreeImageListener(nsTreeBodyFrame *aTreeFrame);
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_IMGINOTIFICATIONOBSERVER
+
+  NS_IMETHOD ClearFrame();
+
+  friend class nsTreeBodyFrame;
+
+protected:
+  ~nsTreeImageListener();
+
+  void UnsuppressInvalidation() { mInvalidationSuppressed = false; }
+  void Invalidate();
+  void AddCell(int32_t aIndex, nsITreeColumn* aCol);
+
+private:
+  nsTreeBodyFrame* mTreeFrame;
+
+  // A guard that prevents us from recursive painting.
+  bool mInvalidationSuppressed;
+
+  class InvalidationArea {
+    public:
+      explicit InvalidationArea(nsITreeColumn* aCol);
+      ~InvalidationArea() { delete mNext; }
+
+      friend class nsTreeImageListener;
+
+    protected:
+      void AddRow(int32_t aIndex);
+      nsITreeColumn* GetCol() { return mCol.get(); }
+      int32_t GetMin() { return mMin; }
+      int32_t GetMax() { return mMax; }
+      InvalidationArea* GetNext() { return mNext; }
+      void SetNext(InvalidationArea* aNext) { mNext = aNext; }
+
+    private:
+      nsCOMPtr<nsITreeColumn> mCol;
+      int32_t                 mMin;
+      int32_t                 mMax;
+      InvalidationArea*       mNext;
+  };
+
+  InvalidationArea* mInvalidationArea;
+};
+
+#endif // nsTreeImageListener_h__
diff --git a/layout/xul/tree/nsTreeSelection.cpp b/layout/xul/tree/nsTreeSelection.cpp
new file mode 100644
index 0000000000..1d251a096f
--- /dev/null
+++ b/layout/xul/tree/nsTreeSelection.cpp
@@ -0,0 +1,866 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/AsyncEventDispatcher.h"
+#include "nsCOMPtr.h"
+#include "nsTreeSelection.h"
+#include "nsIBoxObject.h"
+#include "nsITreeBoxObject.h"
+#include "nsITreeView.h"
+#include "nsString.h"
+#include "nsIDOMElement.h"
+#include "nsDOMClassInfoID.h"
+#include "nsIContent.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsComponentManagerUtils.h"
+
+using namespace mozilla;
+
+// A helper class for managing our ranges of selection.
+struct nsTreeRange
+{
+  nsTreeSelection* mSelection;
+
+  nsTreeRange* mPrev;
+  nsTreeRange* mNext;
+
+  int32_t mMin;
+  int32_t mMax;
+
+  nsTreeRange(nsTreeSelection* aSel, int32_t aSingleVal)
+    :mSelection(aSel), mPrev(nullptr), mNext(nullptr), mMin(aSingleVal), mMax(aSingleVal) {}
+  nsTreeRange(nsTreeSelection* aSel, int32_t aMin, int32_t aMax) 
+    :mSelection(aSel), mPrev(nullptr), mNext(nullptr), mMin(aMin), mMax(aMax) {}
+
+  ~nsTreeRange() { delete mNext; }
+
+  void Connect(nsTreeRange* aPrev = nullptr, nsTreeRange* aNext = nullptr) {
+    if (aPrev)
+      aPrev->mNext = this;
+    else
+      mSelection->mFirstRange = this;
+
+    if (aNext)
+      aNext->mPrev = this;
+
+    mPrev = aPrev;
+    mNext = aNext;
+  }
+
+  nsresult RemoveRange(int32_t aStart, int32_t aEnd) {
+    // This should so be a loop... sigh...
+    // We start past the range to remove, so no more to remove
+    if (aEnd < mMin)
+      return NS_OK;
+    // We are the last range to be affected
+    if (aEnd < mMax) {
+      if (aStart <= mMin) {
+        // Just chop the start of the range off
+        mMin = aEnd + 1;
+      } else {
+        // We need to split the range
+        nsTreeRange* range = new nsTreeRange(mSelection, aEnd + 1, mMax);
+        if (!range)
+          return NS_ERROR_OUT_OF_MEMORY;
+
+        mMax = aStart - 1;
+        range->Connect(this, mNext);
+      }
+      return NS_OK;
+    }
+    nsTreeRange* next = mNext;
+    if (aStart <= mMin) {
+      // The remove includes us, remove ourselves from the list
+      if (mPrev)
+        mPrev->mNext = next;
+      else
+        mSelection->mFirstRange = next;
+
+      if (next)
+        next->mPrev = mPrev;
+      mPrev = mNext = nullptr;
+      delete this;
+    } else if (aStart <= mMax) {
+      // Just chop the end of the range off
+      mMax = aStart - 1;
+    }
+    return next ? next->RemoveRange(aStart, aEnd) : NS_OK;
+  }
+
+  nsresult Remove(int32_t aIndex) {
+    if (aIndex >= mMin && aIndex <= mMax) {
+      // We have found the range that contains us.
+      if (mMin == mMax) {
+        // Delete the whole range.
+        if (mPrev)
+          mPrev->mNext = mNext;
+        if (mNext)
+          mNext->mPrev = mPrev;
+        nsTreeRange* first = mSelection->mFirstRange;
+        if (first == this)
+          mSelection->mFirstRange = mNext;
+        mNext = mPrev = nullptr;
+        delete this;
+      }
+      else if (aIndex == mMin)
+        mMin++;
+      else if (aIndex == mMax)
+        mMax--;
+      else {
+        // We have to break this range.
+        nsTreeRange* newRange = new nsTreeRange(mSelection, aIndex + 1, mMax);
+        if (!newRange)
+          return NS_ERROR_OUT_OF_MEMORY;
+
+        newRange->Connect(this, mNext);
+        mMax = aIndex - 1;
+      }
+    }
+    else if (mNext)
+      return mNext->Remove(aIndex);
+
+    return NS_OK;
+  }
+
+  nsresult Add(int32_t aIndex) {
+    if (aIndex < mMin) {
+      // We have found a spot to insert.
+      if (aIndex + 1 == mMin)
+        mMin = aIndex;
+      else if (mPrev && mPrev->mMax+1 == aIndex)
+        mPrev->mMax = aIndex;
+      else {
+        // We have to create a new range.
+        nsTreeRange* newRange = new nsTreeRange(mSelection, aIndex);
+        if (!newRange)
+          return NS_ERROR_OUT_OF_MEMORY;
+
+        newRange->Connect(mPrev, this);
+      }
+    }
+    else if (mNext)
+      mNext->Add(aIndex);
+    else {
+      // Insert on to the end.
+      if (mMax+1 == aIndex)
+        mMax = aIndex;
+      else {
+        // We have to create a new range.
+        nsTreeRange* newRange = new nsTreeRange(mSelection, aIndex);
+        if (!newRange)
+          return NS_ERROR_OUT_OF_MEMORY;
+
+        newRange->Connect(this, nullptr);
+      }
+    }
+    return NS_OK;
+  }
+
+  bool Contains(int32_t aIndex) {
+    if (aIndex >= mMin && aIndex <= mMax)
+      return true;
+
+    if (mNext)
+      return mNext->Contains(aIndex);
+
+    return false;
+  }
+
+  int32_t Count() {
+    int32_t total = mMax - mMin + 1;
+    if (mNext)
+      total += mNext->Count();
+    return total;
+  }
+
+  static void CollectRanges(nsTreeRange* aRange, nsTArray<int32_t>& aRanges)
+  {
+    nsTreeRange* cur = aRange;
+    while (cur) {
+      aRanges.AppendElement(cur->mMin);
+      aRanges.AppendElement(cur->mMax);
+      cur = cur->mNext;
+    }
+  }
+  
+  static void InvalidateRanges(nsITreeBoxObject* aTree,
+                               nsTArray<int32_t>& aRanges)
+  {
+    if (aTree) {
+      nsCOMPtr<nsITreeBoxObject> tree = aTree;
+      for (uint32_t i = 0; i < aRanges.Length(); i += 2) {
+        aTree->InvalidateRange(aRanges[i], aRanges[i + 1]);
+      }
+    }
+  }
+
+  void Invalidate() {
+    nsTArray<int32_t> ranges;
+    CollectRanges(this, ranges);
+    InvalidateRanges(mSelection->mTree, ranges);
+    
+  }
+
+  void RemoveAllBut(int32_t aIndex) {
+    if (aIndex >= mMin && aIndex <= mMax) {
+
+      // Invalidate everything in this list.
+      nsTArray<int32_t> ranges;
+      CollectRanges(mSelection->mFirstRange, ranges);
+
+      mMin = aIndex;
+      mMax = aIndex;
+      
+      nsTreeRange* first = mSelection->mFirstRange;
+      if (mPrev)
+        mPrev->mNext = mNext;
+      if (mNext)
+        mNext->mPrev = mPrev;
+      mNext = mPrev = nullptr;
+      
+      if (first != this) {
+        delete mSelection->mFirstRange;
+        mSelection->mFirstRange = this;
+      }
+      InvalidateRanges(mSelection->mTree, ranges);
+    }
+    else if (mNext)
+      mNext->RemoveAllBut(aIndex);
+  }
+
+  void Insert(nsTreeRange* aRange) {
+    if (mMin >= aRange->mMax)
+      aRange->Connect(mPrev, this);
+    else if (mNext)
+      mNext->Insert(aRange);
+    else 
+      aRange->Connect(this, nullptr);
+  }
+};
+
+nsTreeSelection::nsTreeSelection(nsITreeBoxObject* aTree)
+  : mTree(aTree),
+    mSuppressed(false),
+    mCurrentIndex(-1),
+    mShiftSelectPivot(-1),
+    mFirstRange(nullptr)
+{
+}
+
+nsTreeSelection::~nsTreeSelection()
+{
+  delete mFirstRange;
+  if (mSelectTimer)
+    mSelectTimer->Cancel();
+}
+
+NS_IMPL_CYCLE_COLLECTION(nsTreeSelection, mTree, mCurrentColumn)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsTreeSelection)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsTreeSelection)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsTreeSelection)
+  NS_INTERFACE_MAP_ENTRY(nsITreeSelection)
+  NS_INTERFACE_MAP_ENTRY(nsINativeTreeSelection)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+  NS_DOM_INTERFACE_MAP_ENTRY_CLASSINFO(TreeSelection)
+NS_INTERFACE_MAP_END
+
+NS_IMETHODIMP nsTreeSelection::GetTree(nsITreeBoxObject * *aTree)
+{
+  NS_IF_ADDREF(*aTree = mTree);
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::SetTree(nsITreeBoxObject * aTree)
+{
+  if (mSelectTimer) {
+    mSelectTimer->Cancel();
+    mSelectTimer = nullptr;
+  }
+
+  // Make sure aTree really implements nsITreeBoxObject and nsIBoxObject!
+  nsCOMPtr<nsIBoxObject> bo = do_QueryInterface(aTree);
+  mTree = do_QueryInterface(bo);
+  NS_ENSURE_STATE(mTree == aTree);
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::GetSingle(bool* aSingle)
+{
+  if (!mTree)
+    return NS_ERROR_NULL_POINTER;
+
+  nsCOMPtr<nsIBoxObject> boxObject = do_QueryInterface(mTree);
+
+  nsCOMPtr<nsIDOMElement> element;
+  boxObject->GetElement(getter_AddRefs(element));
+
+  nsCOMPtr<nsIContent> content = do_QueryInterface(element);
+
+  static nsIContent::AttrValuesArray strings[] =
+    {&nsGkAtoms::single, &nsGkAtoms::cell, &nsGkAtoms::text, nullptr};
+
+  *aSingle = content->FindAttrValueIn(kNameSpaceID_None,
+                                      nsGkAtoms::seltype,
+                                      strings, eCaseMatters) >= 0;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::IsSelected(int32_t aIndex, bool* aResult)
+{
+  if (mFirstRange)
+    *aResult = mFirstRange->Contains(aIndex);
+  else
+    *aResult = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::TimedSelect(int32_t aIndex, int32_t aMsec)
+{
+  bool suppressSelect = mSuppressed;
+
+  if (aMsec != -1)
+    mSuppressed = true;
+
+  nsresult rv = Select(aIndex);
+  if (NS_FAILED(rv))
+    return rv;
+
+  if (aMsec != -1) {
+    mSuppressed = suppressSelect;
+    if (!mSuppressed) {
+      if (mSelectTimer)
+        mSelectTimer->Cancel();
+
+      mSelectTimer = do_CreateInstance("@mozilla.org/timer;1");
+      mSelectTimer->InitWithFuncCallback(SelectCallback, this, aMsec, 
+                                         nsITimer::TYPE_ONE_SHOT);
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::Select(int32_t aIndex)
+{
+  mShiftSelectPivot = -1;
+
+  nsresult rv = SetCurrentIndex(aIndex);
+  if (NS_FAILED(rv))
+    return rv;
+
+  if (mFirstRange) {
+    bool alreadySelected = mFirstRange->Contains(aIndex);
+
+    if (alreadySelected) {
+      int32_t count = mFirstRange->Count();
+      if (count > 1) {
+        // We need to deselect everything but our item.
+        mFirstRange->RemoveAllBut(aIndex);
+        FireOnSelectHandler();
+      }
+      return NS_OK;
+    }
+    else {
+      // Clear out our selection.
+      mFirstRange->Invalidate();
+      delete mFirstRange;
+    }
+  }
+
+  // Create our new selection.
+  mFirstRange = new nsTreeRange(this, aIndex);
+  if (!mFirstRange)
+    return NS_ERROR_OUT_OF_MEMORY;
+
+  mFirstRange->Invalidate();
+
+  // Fire the select event
+  FireOnSelectHandler();
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::ToggleSelect(int32_t aIndex)
+{
+  // There are six cases that can occur on a ToggleSelect with our
+  // range code.
+  // (1) A new range should be made for a selection.
+  // (2) A single range is removed from the selection.
+  // (3) The item is added to an existing range.
+  // (4) The item is removed from an existing range.
+  // (5) The addition of the item causes two ranges to be merged.
+  // (6) The removal of the item causes two ranges to be split.
+  mShiftSelectPivot = -1;
+  nsresult rv = SetCurrentIndex(aIndex);
+  if (NS_FAILED(rv))
+    return rv;
+
+  if (!mFirstRange)
+    Select(aIndex);
+  else {
+    if (!mFirstRange->Contains(aIndex)) {
+      bool single;
+      rv = GetSingle(&single);
+      if (NS_SUCCEEDED(rv) && !single)
+        rv = mFirstRange->Add(aIndex);
+    }
+    else
+      rv = mFirstRange->Remove(aIndex);
+    if (NS_SUCCEEDED(rv)) {
+      if (mTree)
+        mTree->InvalidateRow(aIndex);
+
+      FireOnSelectHandler();
+    }
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP nsTreeSelection::RangedSelect(int32_t aStartIndex, int32_t aEndIndex, bool aAugment)
+{
+  bool single;
+  nsresult rv = GetSingle(&single);
+  if (NS_FAILED(rv))
+    return rv;
+
+  if ((mFirstRange || (aStartIndex != aEndIndex)) && single)
+    return NS_OK;
+
+  if (!aAugment) {
+    // Clear our selection.
+    if (mFirstRange) {
+        mFirstRange->Invalidate();
+        delete mFirstRange;
+        mFirstRange = nullptr;
+    }
+  }
+
+  if (aStartIndex == -1) {
+    if (mShiftSelectPivot != -1)
+      aStartIndex = mShiftSelectPivot;
+    else if (mCurrentIndex != -1)
+      aStartIndex = mCurrentIndex;
+    else
+      aStartIndex = aEndIndex;
+  }
+
+  mShiftSelectPivot = aStartIndex;
+  rv = SetCurrentIndex(aEndIndex);
+  if (NS_FAILED(rv))
+    return rv;
+  
+  int32_t start = aStartIndex < aEndIndex ? aStartIndex : aEndIndex;
+  int32_t end = aStartIndex < aEndIndex ? aEndIndex : aStartIndex;
+
+  if (aAugment && mFirstRange) {
+    // We need to remove all the items within our selected range from the selection,
+    // and then we insert our new range into the list.
+    nsresult rv = mFirstRange->RemoveRange(start, end);
+    if (NS_FAILED(rv))
+      return rv;
+  }
+
+  nsTreeRange* range = new nsTreeRange(this, start, end);
+  if (!range)
+    return NS_ERROR_OUT_OF_MEMORY;
+
+  range->Invalidate();
+
+  if (aAugment && mFirstRange)
+    mFirstRange->Insert(range);
+  else
+    mFirstRange = range;
+
+  FireOnSelectHandler();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::ClearRange(int32_t aStartIndex, int32_t aEndIndex)
+{
+  nsresult rv = SetCurrentIndex(aEndIndex);
+  if (NS_FAILED(rv))
+    return rv;
+
+  if (mFirstRange) {
+    int32_t start = aStartIndex < aEndIndex ? aStartIndex : aEndIndex;
+    int32_t end = aStartIndex < aEndIndex ? aEndIndex : aStartIndex;
+
+    mFirstRange->RemoveRange(start, end);
+
+    if (mTree)
+      mTree->InvalidateRange(start, end);
+  }
+  
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::ClearSelection()
+{
+  if (mFirstRange) {
+    mFirstRange->Invalidate();
+    delete mFirstRange;
+    mFirstRange = nullptr;
+  }
+  mShiftSelectPivot = -1;
+
+  FireOnSelectHandler();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::InvertSelection()
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP nsTreeSelection::SelectAll()
+{
+  if (!mTree)
+    return NS_OK;
+
+  nsCOMPtr<nsITreeView> view;
+  mTree->GetView(getter_AddRefs(view));
+  if (!view)
+    return NS_OK;
+
+  int32_t rowCount;
+  view->GetRowCount(&rowCount);
+  bool single;
+  nsresult rv = GetSingle(&single);
+  if (NS_FAILED(rv))
+    return rv;
+
+  if (rowCount == 0 || (rowCount > 1 && single))
+    return NS_OK;
+
+  mShiftSelectPivot = -1;
+
+  // Invalidate not necessary when clearing selection, since 
+  // we're going to invalidate the world on the SelectAll.
+  delete mFirstRange;
+
+  mFirstRange = new nsTreeRange(this, 0, rowCount-1);
+  mFirstRange->Invalidate();
+
+  FireOnSelectHandler();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::GetRangeCount(int32_t* aResult)
+{
+  int32_t count = 0;
+  nsTreeRange* curr = mFirstRange;
+  while (curr) {
+    count++;
+    curr = curr->mNext;
+  }
+
+  *aResult = count;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::GetRangeAt(int32_t aIndex, int32_t* aMin, int32_t* aMax)
+{
+  *aMin = *aMax = -1;
+  int32_t i = -1;
+  nsTreeRange* curr = mFirstRange;
+  while (curr) {
+    i++;
+    if (i == aIndex) {
+      *aMin = curr->mMin;
+      *aMax = curr->mMax;
+      break;
+    }
+    curr = curr->mNext;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::GetCount(int32_t *count)
+{
+  if (mFirstRange)
+    *count = mFirstRange->Count();
+  else // No range available, so there's no selected row.
+    *count = 0;
+  
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::GetSelectEventsSuppressed(bool *aSelectEventsSuppressed)
+{
+  *aSelectEventsSuppressed = mSuppressed;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::SetSelectEventsSuppressed(bool aSelectEventsSuppressed)
+{
+  mSuppressed = aSelectEventsSuppressed;
+  if (!mSuppressed)
+    FireOnSelectHandler();
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::GetCurrentIndex(int32_t *aCurrentIndex)
+{
+  *aCurrentIndex = mCurrentIndex;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::SetCurrentIndex(int32_t aIndex)
+{
+  if (!mTree) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  if (mCurrentIndex == aIndex) {
+    return NS_OK;
+  }
+  if (mCurrentIndex != -1 && mTree)
+    mTree->InvalidateRow(mCurrentIndex);
+  
+  mCurrentIndex = aIndex;
+  if (!mTree)
+    return NS_OK;
+  
+  if (aIndex != -1)
+    mTree->InvalidateRow(aIndex);
+
+  // Fire DOMMenuItemActive or DOMMenuItemInactive event for tree.
+  nsCOMPtr<nsIBoxObject> boxObject = do_QueryInterface(mTree);
+  NS_ASSERTION(boxObject, "no box object!");
+  if (!boxObject)
+    return NS_ERROR_UNEXPECTED;
+  nsCOMPtr<nsIDOMElement> treeElt;
+  boxObject->GetElement(getter_AddRefs(treeElt));
+
+  nsCOMPtr<nsINode> treeDOMNode(do_QueryInterface(treeElt));
+  NS_ENSURE_STATE(treeDOMNode);
+
+  NS_NAMED_LITERAL_STRING(DOMMenuItemActive, "DOMMenuItemActive");
+  NS_NAMED_LITERAL_STRING(DOMMenuItemInactive, "DOMMenuItemInactive");
+
+  RefPtr<AsyncEventDispatcher> asyncDispatcher =
+    new AsyncEventDispatcher(treeDOMNode,
+                             (aIndex != -1 ? DOMMenuItemActive :
+                                             DOMMenuItemInactive),
+                             true, false);
+  return asyncDispatcher->PostDOMEvent();
+}
+
+NS_IMETHODIMP nsTreeSelection::GetCurrentColumn(nsITreeColumn** aCurrentColumn)
+{
+  NS_IF_ADDREF(*aCurrentColumn = mCurrentColumn);
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsTreeSelection::SetCurrentColumn(nsITreeColumn* aCurrentColumn)
+{
+  if (!mTree) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  if (mCurrentColumn == aCurrentColumn) {
+    return NS_OK;
+  }
+
+  if (mCurrentColumn) {
+    if (mFirstRange)
+      mTree->InvalidateCell(mFirstRange->mMin, mCurrentColumn);
+    if (mCurrentIndex != -1)
+      mTree->InvalidateCell(mCurrentIndex, mCurrentColumn);
+  }
+  
+  mCurrentColumn = aCurrentColumn;
+  
+  if (mCurrentColumn) {
+    if (mFirstRange)
+      mTree->InvalidateCell(mFirstRange->mMin, mCurrentColumn);
+    if (mCurrentIndex != -1)
+      mTree->InvalidateCell(mCurrentIndex, mCurrentColumn);
+  }
+
+  return NS_OK;
+}
+
+#define ADD_NEW_RANGE(macro_range, macro_selection, macro_start, macro_end) \
+  { \
+    int32_t start = macro_start; \
+    int32_t end = macro_end; \
+    if (start > end) { \
+      end = start; \
+    } \
+    nsTreeRange* macro_new_range = new nsTreeRange(macro_selection, start, end); \
+    if (macro_range) \
+      macro_range->Insert(macro_new_range); \
+    else \
+      macro_range = macro_new_range; \
+  }
+
+NS_IMETHODIMP
+nsTreeSelection::AdjustSelection(int32_t aIndex, int32_t aCount)
+{
+  NS_ASSERTION(aCount != 0, "adjusting by zero");
+  if (!aCount) return NS_OK;
+
+  // adjust mShiftSelectPivot, if necessary
+  if ((mShiftSelectPivot != 1) && (aIndex <= mShiftSelectPivot)) {
+    // if we are deleting and the delete includes the shift select pivot, reset it
+    if (aCount < 0 && (mShiftSelectPivot <= (aIndex -aCount -1))) {
+        mShiftSelectPivot = -1;
+    }
+    else {
+        mShiftSelectPivot += aCount;
+    }
+  }
+
+  // adjust mCurrentIndex, if necessary
+  if ((mCurrentIndex != -1) && (aIndex <= mCurrentIndex)) {
+    // if we are deleting and the delete includes the current index, reset it
+    if (aCount < 0 && (mCurrentIndex <= (aIndex -aCount -1))) {
+        mCurrentIndex = -1;
+    }
+    else {
+        mCurrentIndex += aCount;
+    }
+  }
+
+  // no selection, so nothing to do.
+  if (!mFirstRange) return NS_OK;
+
+  bool selChanged = false;
+  nsTreeRange* oldFirstRange = mFirstRange;
+  nsTreeRange* curr = mFirstRange;
+  mFirstRange = nullptr;
+  while (curr) {
+    if (aCount > 0) {
+      // inserting
+      if (aIndex > curr->mMax) {
+        // adjustment happens after the range, so no change
+        ADD_NEW_RANGE(mFirstRange, this, curr->mMin, curr->mMax);
+      }
+      else if (aIndex <= curr->mMin) {  
+        // adjustment happens before the start of the range, so shift down
+        ADD_NEW_RANGE(mFirstRange, this, curr->mMin + aCount, curr->mMax + aCount);
+        selChanged = true;
+      }
+      else {
+        // adjustment happen inside the range.
+        // break apart the range and create two ranges
+        ADD_NEW_RANGE(mFirstRange, this, curr->mMin, aIndex - 1);
+        ADD_NEW_RANGE(mFirstRange, this, aIndex + aCount, curr->mMax + aCount);
+        selChanged = true;
+      }
+    }
+    else {
+      // deleting
+      if (aIndex > curr->mMax) {
+        // adjustment happens after the range, so no change
+        ADD_NEW_RANGE(mFirstRange, this, curr->mMin, curr->mMax);
+      }
+      else {
+        // remember, aCount is negative
+        selChanged = true;
+        int32_t lastIndexOfAdjustment = aIndex - aCount - 1;
+        if (aIndex <= curr->mMin) {
+          if (lastIndexOfAdjustment < curr->mMin) {
+            // adjustment happens before the start of the range, so shift up
+            ADD_NEW_RANGE(mFirstRange, this, curr->mMin + aCount, curr->mMax + aCount);
+          }
+          else if (lastIndexOfAdjustment >= curr->mMax) {
+            // adjustment contains the range.  remove the range by not adding it to the newRange
+          }
+          else {
+            // adjustment starts before the range, and ends in the middle of it, so trim the range
+            ADD_NEW_RANGE(mFirstRange, this, aIndex, curr->mMax + aCount)
+          }
+        }
+        else if (lastIndexOfAdjustment >= curr->mMax) {
+         // adjustment starts in the middle of the current range, and contains the end of the range, so trim the range
+         ADD_NEW_RANGE(mFirstRange, this, curr->mMin, aIndex - 1)
+        }
+        else {
+          // range contains the adjustment, so shorten the range
+          ADD_NEW_RANGE(mFirstRange, this, curr->mMin, curr->mMax + aCount)
+        }
+      }
+    }
+    curr = curr->mNext;
+  }
+
+  delete oldFirstRange;
+
+  // Fire the select event
+  if (selChanged)
+    FireOnSelectHandler();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeSelection::InvalidateSelection()
+{
+  if (mFirstRange)
+    mFirstRange->Invalidate();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTreeSelection::GetShiftSelectPivot(int32_t* aIndex)
+{
+  *aIndex = mShiftSelectPivot;
+  return NS_OK;
+}
+
+
+nsresult
+nsTreeSelection::FireOnSelectHandler()
+{
+  if (mSuppressed || !mTree)
+    return NS_OK;
+
+  nsCOMPtr<nsIBoxObject> boxObject = do_QueryInterface(mTree);
+  NS_ASSERTION(boxObject, "no box object!");
+  if (!boxObject)
+     return NS_ERROR_UNEXPECTED;
+  nsCOMPtr<nsIDOMElement> elt;
+  boxObject->GetElement(getter_AddRefs(elt));
+  NS_ENSURE_STATE(elt);
+
+  nsCOMPtr<nsINode> node(do_QueryInterface(elt));
+  NS_ENSURE_STATE(node);
+
+  RefPtr<AsyncEventDispatcher> asyncDispatcher =
+    new AsyncEventDispatcher(node, NS_LITERAL_STRING("select"), true, false);
+  asyncDispatcher->RunDOMEventWhenSafe();
+  return NS_OK;
+}
+
+void
+nsTreeSelection::SelectCallback(nsITimer *aTimer, void *aClosure)
+{
+  RefPtr<nsTreeSelection> self = static_cast<nsTreeSelection*>(aClosure);
+  if (self) {
+    self->FireOnSelectHandler();
+    aTimer->Cancel();
+    self->mSelectTimer = nullptr;
+  }
+}
+
+///////////////////////////////////////////////////////////////////////////////////
+
+nsresult
+NS_NewTreeSelection(nsITreeBoxObject* aTree, nsITreeSelection** aResult)
+{
+  *aResult = new nsTreeSelection(aTree);
+  if (!*aResult)
+    return NS_ERROR_OUT_OF_MEMORY;
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}
diff --git a/layout/xul/tree/nsTreeSelection.h b/layout/xul/tree/nsTreeSelection.h
new file mode 100644
index 0000000000..41ffe31fb3
--- /dev/null
+++ b/layout/xul/tree/nsTreeSelection.h
@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 3; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTreeSelection_h__
+#define nsTreeSelection_h__
+
+#include "nsITreeSelection.h"
+#include "nsITreeColumns.h"
+#include "nsITimer.h"
+#include "nsCycleCollectionParticipant.h"
+#include "mozilla/Attributes.h"
+
+class nsITreeBoxObject;
+struct nsTreeRange;
+
+class nsTreeSelection final : public nsINativeTreeSelection
+{
+public:
+  explicit nsTreeSelection(nsITreeBoxObject* aTree);
+   
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS(nsTreeSelection)
+  NS_DECL_NSITREESELECTION
+
+  // nsINativeTreeSelection: Untrusted code can use us
+  NS_IMETHOD EnsureNative() override { return NS_OK; }
+
+  friend struct nsTreeRange;
+
+protected:
+  ~nsTreeSelection();
+
+  nsresult FireOnSelectHandler();
+  static void SelectCallback(nsITimer *aTimer, void *aClosure);
+
+protected:
+  // Members
+  nsCOMPtr<nsITreeBoxObject> mTree; // The tree will hold on to us through the view and let go when it dies.
+
+  bool mSuppressed; // Whether or not we should be firing onselect events.
+  int32_t mCurrentIndex; // The item to draw the rect around. The last one clicked, etc.
+  nsCOMPtr<nsITreeColumn> mCurrentColumn;
+  int32_t mShiftSelectPivot; // Used when multiple SHIFT+selects are performed to pivot on.
+
+  nsTreeRange* mFirstRange; // Our list of ranges.
+
+  nsCOMPtr<nsITimer> mSelectTimer;
+};
+
+nsresult
+NS_NewTreeSelection(nsITreeBoxObject* aTree, nsITreeSelection** aResult);
+
+#endif
diff --git a/layout/xul/tree/nsTreeStyleCache.cpp b/layout/xul/tree/nsTreeStyleCache.cpp
new file mode 100644
index 0000000000..74b8a89c47
--- /dev/null
+++ b/layout/xul/tree/nsTreeStyleCache.cpp
@@ -0,0 +1,99 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTreeStyleCache.h"
+#include "nsStyleSet.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/StyleSetHandle.h"
+#include "mozilla/StyleSetHandleInlines.h"
+
+nsTreeStyleCache::Transition::Transition(DFAState aState, nsIAtom* aSymbol)
+  : mState(aState), mInputSymbol(aSymbol)
+{
+}
+
+bool
+nsTreeStyleCache::Transition::operator==(const Transition& aOther) const
+{
+  return aOther.mState == mState && aOther.mInputSymbol == mInputSymbol;
+}
+
+uint32_t
+nsTreeStyleCache::Transition::Hash() const
+{
+  // Make a 32-bit integer that combines the low-order 16 bits of the state and the input symbol.
+  uint32_t hb = mState << 16;
+  uint32_t lb = (NS_PTR_TO_UINT32(mInputSymbol.get()) << 16) >> 16;
+  return hb+lb;
+}
+
+
+// The style context cache impl
+nsStyleContext*
+nsTreeStyleCache::GetStyleContext(nsICSSPseudoComparator* aComparator,
+                                  nsPresContext* aPresContext,
+                                  nsIContent* aContent,
+                                  nsStyleContext* aContext,
+                                  nsIAtom* aPseudoElement,
+                                  const AtomArray & aInputWord)
+{
+  uint32_t count = aInputWord.Length();
+
+  // Go ahead and init the transition table.
+  if (!mTransitionTable) {
+    // Automatic miss. Build the table
+    mTransitionTable = new TransitionTable();
+  }
+
+  // The first transition is always made off the supplied pseudo-element.
+  Transition transition(0, aPseudoElement);
+  DFAState currState = mTransitionTable->Get(transition);
+
+  if (!currState) {
+    // We had a miss. Make a new state and add it to our hash.
+    currState = mNextState;
+    mNextState++;
+    mTransitionTable->Put(transition, currState);
+  }
+
+  for (uint32_t i = 0; i < count; i++) {
+    Transition transition(currState, aInputWord[i]);
+    currState = mTransitionTable->Get(transition);
+
+    if (!currState) {
+      // We had a miss. Make a new state and add it to our hash.
+      currState = mNextState;
+      mNextState++;
+      mTransitionTable->Put(transition, currState);
+    }
+  }
+
+  // We're in a final state.
+  // Look up our style context for this state.
+  nsStyleContext* result = nullptr;
+  if (mCache) {
+    result = mCache->GetWeak(currState);
+  }
+  if (!result) {
+    // We missed the cache. Resolve this pseudo-style.
+    // XXXheycam ServoStyleSets do not support XUL tree styles.
+    if (aPresContext->StyleSet()->IsServo()) {
+      MOZ_CRASH("stylo: ServoStyleSets should not support XUL tree styles yet");
+    }
+    RefPtr<nsStyleContext> newResult = aPresContext->StyleSet()->AsGecko()->
+      ResolveXULTreePseudoStyle(aContent->AsElement(), aPseudoElement,
+                                aContext, aComparator);
+
+    // Put the style context in our table, transferring the owning reference to the table.
+    if (!mCache) {
+      mCache = new StyleContextCache();
+    }
+    result = newResult.get();
+    mCache->Put(currState, newResult.forget());
+  }
+
+  return result;
+}
+
diff --git a/layout/xul/tree/nsTreeStyleCache.h b/layout/xul/tree/nsTreeStyleCache.h
new file mode 100644
index 0000000000..1020b04352
--- /dev/null
+++ b/layout/xul/tree/nsTreeStyleCache.h
@@ -0,0 +1,89 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTreeStyleCache_h__
+#define nsTreeStyleCache_h__
+
+#include "mozilla/Attributes.h"
+#include "nsAutoPtr.h"
+#include "nsIAtom.h"
+#include "nsCOMArray.h"
+#include "nsICSSPseudoComparator.h"
+#include "nsRefPtrHashtable.h"
+#include "nsStyleContext.h"
+
+typedef nsCOMArray<nsIAtom> AtomArray;
+
+class nsTreeStyleCache
+{
+public:
+  nsTreeStyleCache()
+    : mNextState(0)
+  {
+  }
+
+  ~nsTreeStyleCache()
+  {
+    Clear();
+  }
+
+  void Clear()
+  {
+    mTransitionTable = nullptr;
+    mCache = nullptr;
+    mNextState = 0;
+  }
+
+  nsStyleContext* GetStyleContext(nsICSSPseudoComparator* aComparator,
+                                  nsPresContext* aPresContext,
+                                  nsIContent* aContent,
+                                  nsStyleContext* aContext,
+                                  nsIAtom* aPseudoElement,
+                                  const AtomArray & aInputWord);
+
+protected:
+  typedef uint32_t DFAState;
+
+  class Transition final
+  {
+  public:
+    Transition(DFAState aState, nsIAtom* aSymbol);
+    bool operator==(const Transition& aOther) const;
+    uint32_t Hash() const;
+
+  private:
+    DFAState mState;
+    nsCOMPtr<nsIAtom> mInputSymbol;
+  };
+
+  typedef nsDataHashtable<nsGenericHashKey<Transition>, DFAState> TransitionTable;
+
+  // A transition table for a deterministic finite automaton.  The DFA
+  // takes as its input a single pseudoelement and an ordered set of properties.
+  // It transitions on an input word that is the concatenation of the pseudoelement supplied
+  // with the properties in the array.
+  //
+  // It transitions from state to state by looking up entries in the transition table (which is
+  // a mapping from (S,i)->S', where S is the current state, i is the next
+  // property in the input word, and S' is the state to transition to.
+  //
+  // If S' is not found, it is constructed and entered into the hashtable
+  // under the key (S,i).
+  //
+  // Once the entire word has been consumed, the final state is used
+  // to reference the cache table to locate the style context.
+  nsAutoPtr<TransitionTable> mTransitionTable;
+
+  // The cache of all active style contexts.  This is a hash from
+  // a final state in the DFA, Sf, to the resultant style context.
+  typedef nsRefPtrHashtable<nsUint32HashKey, nsStyleContext> StyleContextCache;
+  nsAutoPtr<StyleContextCache> mCache;
+
+  // An integer counter that is used when we need to make new states in the
+  // DFA.
+  DFAState mNextState;
+};
+
+#endif // nsTreeStyleCache_h__
diff --git a/layout/xul/tree/nsTreeUtils.cpp b/layout/xul/tree/nsTreeUtils.cpp
new file mode 100644
index 0000000000..81a56f0e95
--- /dev/null
+++ b/layout/xul/tree/nsTreeUtils.cpp
@@ -0,0 +1,140 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsReadableUtils.h"
+#include "nsTreeUtils.h"
+#include "ChildIterator.h"
+#include "nsCRT.h"
+#include "nsIAtom.h"
+#include "nsNameSpaceManager.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+
+using namespace mozilla;
+
+nsresult
+nsTreeUtils::TokenizeProperties(const nsAString& aProperties, AtomArray & aPropertiesArray)
+{
+  nsAString::const_iterator end;
+  aProperties.EndReading(end);
+
+  nsAString::const_iterator iter;
+  aProperties.BeginReading(iter);
+
+  do {
+    // Skip whitespace
+    while (iter != end && nsCRT::IsAsciiSpace(*iter))
+      ++iter;
+
+    // If only whitespace, we're done
+    if (iter == end)
+      break;
+
+    // Note the first non-whitespace character
+    nsAString::const_iterator first = iter;
+
+    // Advance to the next whitespace character
+    while (iter != end && ! nsCRT::IsAsciiSpace(*iter))
+      ++iter;
+
+    // XXX this would be nonsensical
+    NS_ASSERTION(iter != first, "eh? something's wrong here");
+    if (iter == first)
+      break;
+
+    nsCOMPtr<nsIAtom> atom = NS_Atomize(Substring(first, iter));
+    aPropertiesArray.AppendElement(atom);
+  } while (iter != end);
+
+  return NS_OK;
+}
+
+nsIContent*
+nsTreeUtils::GetImmediateChild(nsIContent* aContainer, nsIAtom* aTag)
+{
+  dom::FlattenedChildIterator iter(aContainer);
+  for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+    if (child->IsXULElement(aTag)) {
+      return child;
+    }
+  }
+
+  return nullptr;
+}
+
+nsIContent*
+nsTreeUtils::GetDescendantChild(nsIContent* aContainer, nsIAtom* aTag)
+{
+  dom::FlattenedChildIterator iter(aContainer);
+  for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+    if (child->IsXULElement(aTag)) {
+      return child;
+    }
+
+    child = GetDescendantChild(child, aTag);
+    if (child) {
+      return child;
+    }
+  }
+
+  return nullptr;
+}
+
+nsresult
+nsTreeUtils::UpdateSortIndicators(nsIContent* aColumn, const nsAString& aDirection)
+{
+  aColumn->SetAttr(kNameSpaceID_None, nsGkAtoms::sortDirection, aDirection, true);
+  aColumn->SetAttr(kNameSpaceID_None, nsGkAtoms::sortActive, NS_LITERAL_STRING("true"), true);
+
+  // Unset sort attribute(s) on the other columns
+  nsCOMPtr<nsIContent> parentContent = aColumn->GetParent();
+  if (parentContent &&
+      parentContent->NodeInfo()->Equals(nsGkAtoms::treecols,
+                                        kNameSpaceID_XUL)) {
+    uint32_t i, numChildren = parentContent->GetChildCount();
+    for (i = 0; i < numChildren; ++i) {
+      nsCOMPtr<nsIContent> childContent = parentContent->GetChildAt(i);
+
+      if (childContent &&
+          childContent != aColumn &&
+          childContent->NodeInfo()->Equals(nsGkAtoms::treecol,
+                                           kNameSpaceID_XUL)) {
+        childContent->UnsetAttr(kNameSpaceID_None,
+                                nsGkAtoms::sortDirection, true);
+        childContent->UnsetAttr(kNameSpaceID_None,
+                                nsGkAtoms::sortActive, true);
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+nsresult
+nsTreeUtils::GetColumnIndex(nsIContent* aColumn, int32_t* aResult)
+{
+  nsIContent* parentContent = aColumn->GetParent();
+  if (parentContent &&
+      parentContent->NodeInfo()->Equals(nsGkAtoms::treecols,
+                                        kNameSpaceID_XUL)) {
+    uint32_t i, numChildren = parentContent->GetChildCount();
+    int32_t colIndex = 0;
+    for (i = 0; i < numChildren; ++i) {
+      nsIContent *childContent = parentContent->GetChildAt(i);
+      if (childContent &&
+          childContent->NodeInfo()->Equals(nsGkAtoms::treecol,
+                                           kNameSpaceID_XUL)) {
+        if (childContent == aColumn) {
+          *aResult = colIndex;
+          return NS_OK;
+        }
+        ++colIndex;
+      }
+    }
+  }
+
+  *aResult = -1;
+  return NS_OK;
+}
diff --git a/layout/xul/tree/nsTreeUtils.h b/layout/xul/tree/nsTreeUtils.h
new file mode 100644
index 0000000000..f2ed2df686
--- /dev/null
+++ b/layout/xul/tree/nsTreeUtils.h
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 3; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTreeUtils_h__
+#define nsTreeUtils_h__
+
+#include "nsError.h"
+#include "nsString.h"
+#include "nsTreeStyleCache.h"
+
+class nsIAtom;
+class nsIContent;
+
+class nsTreeUtils
+{
+  public:
+    /**
+     * Parse a whitespace separated list of properties into an array
+     * of atoms.
+     */
+    static nsresult
+    TokenizeProperties(const nsAString& aProperties, AtomArray & aPropertiesArray);
+
+    static nsIContent*
+    GetImmediateChild(nsIContent* aContainer, nsIAtom* aTag);
+
+    static nsIContent*
+    GetDescendantChild(nsIContent* aContainer, nsIAtom* aTag);
+
+    static nsresult
+    UpdateSortIndicators(nsIContent* aColumn, const nsAString& aDirection);
+
+    static nsresult
+    GetColumnIndex(nsIContent* aColumn, int32_t* aResult);
+};
+
+#endif // nsTreeUtils_h__