Fix for 43467. r=bryner

layout/base/nsIPresShell.h

@@ -65,6 +65,7 @@ class nsIFrameSelection;
 class nsIFrameManager;
 class nsILayoutHistoryState;
 class nsIArena;
+class nsIReflowCallback;
 
 #define NS_IPRESSHELL_IID     \
 { 0x76e79c60, 0x944e, 0x11d1, \
@@ -271,6 +272,8 @@ public:
                                  PRBool aNotify,
                                  nsAttributeChangeType aType) = 0;
 
+  NS_IMETHOD PostReflowCallback(nsIReflowCallback* aCallback) = 0;
+
  /**
    * Reflow batching
    */   

layout/base/nsIReflowCallback.h

@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * The contents of this file are subject to the Netscape Public
+ * License Version 1.1 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ *
+ * The Original Code is Mozilla Communicator client code.
+ *
+ * The Initial Developer of the Original Code is Netscape Communications
+ * Corporation.  Portions created by Netscape are
+ * Copyright (C) 1998 Netscape Communications Corporation. All
+ * Rights Reserved.
+ *
+ * Original Author: David Hyatt (hyatt@netscape.com)
+ *
+ * Contributor(s): 
+ */
+#ifndef nsIReflowCallback_h___
+#define nsIReflowCallback_h___
+
+// {03E6FD70-889C-44b1-8639-A7EF5A80ED5C}
+#define NS_IREFLOWCALLBACK_IID \
+{ 0x3e6fd70, 0x889c, 0x44b1, { 0x86, 0x39, 0xa7, 0xef, 0x5a, 0x80, 0xed, 0x5c } }
+
+class nsIPresShell;
+
+/**
+ * Reflow callback interface
+ */
+class nsIReflowCallback : public nsISupports {
+public:
+  static const nsIID& GetIID() { static nsIID iid = NS_IREFLOWCALLBACK_IID; return iid; }
+
+  NS_IMETHOD ReflowFinished(nsIPresShell* aShell, PRBool* aFlushFlag) = 0;
+};
+
+#endif /* nsIFrameUtil_h___ */

layout/base/nsPresShell.cpp

@@ -103,6 +103,8 @@
 #include "nsIFrameDebug.h"
 #endif
 
+#include "nsIReflowCallback.h"
+
 #include "nsIScriptGlobalObject.h"
 #include "nsIDOMWindow.h"
 #include "nsPIDOMWindow.h"
@@ -572,6 +574,12 @@ struct nsAttributeChangeRequest
   nsAttributeChangeRequest* next;
 };
 
+struct nsCallbackEventRequest
+{
+  nsIReflowCallback* callback;
+  nsCallbackEventRequest* next;
+};
+
 class PresShell : public nsIPresShell, public nsIViewObserver,
                   private nsIDocumentObserver, public nsIFocusTracker,
                   public nsISelectionController,
@@ -651,6 +659,12 @@ public:
                                  const nsString& aValue,
                                  PRBool aNotify,
                                  nsAttributeChangeType aType);
+
+  /**
+   * Post a callback that should be handled after reflow has finished.
+   */
+  NS_IMETHOD PostReflowCallback(nsIReflowCallback* aCallback);
+
   /**
    * Reflow batching
    */   
@@ -792,6 +806,7 @@ protected:
 
   void HandlePostedDOMEvents();
   void HandlePostedAttributeChanges();
+  void HandlePostedReflowCallbacks();
 
   /** notify all external reflow observers that reflow of type "aData" is about
     * to begin.
@@ -866,6 +881,8 @@ protected:
   nsDOMEventRequest* mLastDOMEventRequest;
   nsAttributeChangeRequest* mFirstAttributeRequest;
   nsAttributeChangeRequest* mLastAttributeRequest;
+  nsCallbackEventRequest* mFirstCallbackEventRequest;
+  nsCallbackEventRequest* mLastCallbackEventRequest;
 
   // subshell map
   nsDST*            mSubShellMap;  // map of content/subshell pairs
@@ -993,7 +1010,9 @@ PresShell::PresShell():mStackArena(nsnull),
                        mFirstDOMEventRequest(nsnull),
                        mLastDOMEventRequest(nsnull),
                        mFirstAttributeRequest(nsnull),
-                       mLastAttributeRequest(nsnull)
+                       mLastAttributeRequest(nsnull),
+                       mFirstCallbackEventRequest(nsnull),
+                       mLastCallbackEventRequest(nsnull)
 {
   NS_INIT_REFCNT();
   mIsDestroying = PR_FALSE;
@@ -1881,6 +1900,7 @@ PresShell::ResizeReflow(nscoord aWidth, nscoord aHeight)
   mViewManager->CacheWidgetChanges(PR_FALSE);
   HandlePostedDOMEvents();
   HandlePostedAttributeChanges();
+  HandlePostedReflowCallbacks();
 
   //Send resize event from here.
   nsEvent event;
@@ -3105,6 +3125,29 @@ PresShell::GetGeneratedContentIterator(nsIContent*          aContent,
   return rv;
 }
 
+// Post a request to handle an arbitrary callback after reflow has finished.
+NS_IMETHODIMP
+PresShell::PostReflowCallback(nsIReflowCallback* aCallback)
+{
+  nsCallbackEventRequest* request = nsnull;
+  void* result = nsnull;
+  AllocateFrame(sizeof(nsCallbackEventRequest), &result);
+  request = (nsCallbackEventRequest*)result;
+
+  request->callback = aCallback;
+  NS_ADDREF(aCallback);
+  request->next = nsnull;
+
+  if (mLastCallbackEventRequest) {
+    mLastCallbackEventRequest = mLastCallbackEventRequest->next = request;
+  } else {
+    mFirstCallbackEventRequest = request;
+    mLastCallbackEventRequest = request;
+  }
+ 
+  return NS_OK;
+}
+
 /**
 * Post a request to handle a DOM event after Reflow has finished.
 * The event must have been created with the "new" operator.
@@ -3175,6 +3218,28 @@ PresShell::PostAttributeChange(nsIContent* aContent,
   return NS_OK;
 }
 
+void
+PresShell::HandlePostedReflowCallbacks()
+{
+   PRBool shouldFlush = PR_FALSE;
+   nsCallbackEventRequest* node = mFirstCallbackEventRequest;
+   while(node)
+   {
+      nsIReflowCallback* callback = node->callback;
+      nsCallbackEventRequest* toFree = node;
+      node = node->next;
+      mFirstCallbackEventRequest = node;
+      FreeFrame(sizeof(nsCallbackEventRequest), toFree);
+      callback->ReflowFinished(this, &shouldFlush); 
+      NS_RELEASE(callback);
+   }
+
+   mFirstCallbackEventRequest = mLastCallbackEventRequest = nsnull;
+
+   if (shouldFlush)
+     FlushPendingNotifications();
+}
+
 void
 PresShell::HandlePostedDOMEvents()
 {
@@ -4197,6 +4262,7 @@ PresShell::ProcessReflowCommands(PRBool aInterruptible)
 
   HandlePostedDOMEvents();
   HandlePostedAttributeChanges();
+  HandlePostedReflowCallbacks();
   return NS_OK;
 }
 

layout/base/public/MANIFEST

@@ -31,6 +31,7 @@ nsIPageSequenceFrame.h
 nsIPresContext.h
 nsIPresShell.h
 nsIPresState.h
+nsIReflowCallback.h
 nsIReflowCommand.h
 nsISpaceManager.h
 nsFrameList.h

layout/base/public/Makefile.in

@@ -58,6 +58,7 @@ nsIPageSequenceFrame.h \
 nsIPresContext.h \
 nsIPresShell.h \
 nsIPresState.h \
+nsIReflowCallback.h \
 nsIReflowCommand.h \
 nsIFrameSelection.h \
 nsISpaceManager.h \

layout/base/public/makefile.win

@@ -51,6 +51,7 @@ EXPORTS =				\
 	nsIPresContext.h		\
 	nsIPresShell.h			\
 	nsIPresState.h          \
+  nsIReflowCallback.h \
 	nsIReflowCommand.h		\
 	nsIFrameSelection.h		\
 	nsISpaceManager.h		\

layout/base/public/nsIPresShell.h

@@ -65,6 +65,7 @@ class nsIFrameSelection;
 class nsIFrameManager;
 class nsILayoutHistoryState;
 class nsIArena;
+class nsIReflowCallback;
 
 #define NS_IPRESSHELL_IID     \
 { 0x76e79c60, 0x944e, 0x11d1, \
@@ -271,6 +272,8 @@ public:
                                  PRBool aNotify,
                                  nsAttributeChangeType aType) = 0;
 
+  NS_IMETHOD PostReflowCallback(nsIReflowCallback* aCallback) = 0;
+
  /**
    * Reflow batching
    */   

layout/base/public/nsIReflowCallback.h

@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * The contents of this file are subject to the Netscape Public
+ * License Version 1.1 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ *
+ * The Original Code is Mozilla Communicator client code.
+ *
+ * The Initial Developer of the Original Code is Netscape Communications
+ * Corporation.  Portions created by Netscape are
+ * Copyright (C) 1998 Netscape Communications Corporation. All
+ * Rights Reserved.
+ *
+ * Original Author: David Hyatt (hyatt@netscape.com)
+ *
+ * Contributor(s): 
+ */
+#ifndef nsIReflowCallback_h___
+#define nsIReflowCallback_h___
+
+// {03E6FD70-889C-44b1-8639-A7EF5A80ED5C}
+#define NS_IREFLOWCALLBACK_IID \
+{ 0x3e6fd70, 0x889c, 0x44b1, { 0x86, 0x39, 0xa7, 0xef, 0x5a, 0x80, 0xed, 0x5c } }
+
+class nsIPresShell;
+
+/**
+ * Reflow callback interface
+ */
+class nsIReflowCallback : public nsISupports {
+public:
+  static const nsIID& GetIID() { static nsIID iid = NS_IREFLOWCALLBACK_IID; return iid; }
+
+  NS_IMETHOD ReflowFinished(nsIPresShell* aShell, PRBool* aFlushFlag) = 0;
+};
+
+#endif /* nsIFrameUtil_h___ */

layout/generic/nsGfxScrollFrame.cpp

@@ -51,6 +51,8 @@
 #include "nsIElementFactory.h"
 #include "nsBoxLayoutState.h"
 #include "nsINodeInfo.h"
+#include "nsIScrollbarFrame.h"
+#include "nsIScrollbarMediator.h"
 
 static NS_DEFINE_IID(kWidgetCID, NS_CHILD_CID);
 static NS_DEFINE_IID(kScrollingViewCID, NS_SCROLLING_VIEW_CID);
@@ -1367,6 +1369,17 @@ nsGfxScrollFrameInner::SetScrollbarVisibility(nsIBox* aScrollbar, PRBool aVisibl
      content->SetAttribute(kNameSpaceID_None, nsXULAtoms::collapsed, NS_ConvertToString("true"), PR_TRUE);
   else
      content->UnsetAttribute(kNameSpaceID_None, nsXULAtoms::collapsed, PR_TRUE);
+
+  nsCOMPtr<nsIScrollbarFrame> scrollbar(do_QueryInterface(aScrollbar));
+  if (scrollbar) {
+    // See if we have a mediator.
+    nsCOMPtr<nsIScrollbarMediator> mediator;
+    scrollbar->GetScrollbarMediator(getter_AddRefs(mediator));
+    if (mediator) {
+      // Inform the mediator of the visibility change.
+      mediator->VisibilityChanged(aVisible);
+    }
+  }
 }
 
 PRInt32

layout/html/base/src/nsGfxScrollFrame.cpp

@@ -51,6 +51,8 @@
 #include "nsIElementFactory.h"
 #include "nsBoxLayoutState.h"
 #include "nsINodeInfo.h"
+#include "nsIScrollbarFrame.h"
+#include "nsIScrollbarMediator.h"
 
 static NS_DEFINE_IID(kWidgetCID, NS_CHILD_CID);
 static NS_DEFINE_IID(kScrollingViewCID, NS_SCROLLING_VIEW_CID);
@@ -1367,6 +1369,17 @@ nsGfxScrollFrameInner::SetScrollbarVisibility(nsIBox* aScrollbar, PRBool aVisibl
      content->SetAttribute(kNameSpaceID_None, nsXULAtoms::collapsed, NS_ConvertToString("true"), PR_TRUE);
   else
      content->UnsetAttribute(kNameSpaceID_None, nsXULAtoms::collapsed, PR_TRUE);
+
+  nsCOMPtr<nsIScrollbarFrame> scrollbar(do_QueryInterface(aScrollbar));
+  if (scrollbar) {
+    // See if we have a mediator.
+    nsCOMPtr<nsIScrollbarMediator> mediator;
+    scrollbar->GetScrollbarMediator(getter_AddRefs(mediator));
+    if (mediator) {
+      // Inform the mediator of the visibility change.
+      mediator->VisibilityChanged(aVisible);
+    }
+  }
 }
 
 PRInt32

layout/html/base/src/nsPresShell.cpp

@@ -103,6 +103,8 @@
 #include "nsIFrameDebug.h"
 #endif
 
+#include "nsIReflowCallback.h"
+
 #include "nsIScriptGlobalObject.h"
 #include "nsIDOMWindow.h"
 #include "nsPIDOMWindow.h"
@@ -572,6 +574,12 @@ struct nsAttributeChangeRequest
   nsAttributeChangeRequest* next;
 };
 
+struct nsCallbackEventRequest
+{
+  nsIReflowCallback* callback;
+  nsCallbackEventRequest* next;
+};
+
 class PresShell : public nsIPresShell, public nsIViewObserver,
                   private nsIDocumentObserver, public nsIFocusTracker,
                   public nsISelectionController,
@@ -651,6 +659,12 @@ public:
                                  const nsString& aValue,
                                  PRBool aNotify,
                                  nsAttributeChangeType aType);
+
+  /**
+   * Post a callback that should be handled after reflow has finished.
+   */
+  NS_IMETHOD PostReflowCallback(nsIReflowCallback* aCallback);
+
   /**
    * Reflow batching
    */   
@@ -792,6 +806,7 @@ protected:
 
   void HandlePostedDOMEvents();
   void HandlePostedAttributeChanges();
+  void HandlePostedReflowCallbacks();
 
   /** notify all external reflow observers that reflow of type "aData" is about
     * to begin.
@@ -866,6 +881,8 @@ protected:
   nsDOMEventRequest* mLastDOMEventRequest;
   nsAttributeChangeRequest* mFirstAttributeRequest;
   nsAttributeChangeRequest* mLastAttributeRequest;
+  nsCallbackEventRequest* mFirstCallbackEventRequest;
+  nsCallbackEventRequest* mLastCallbackEventRequest;
 
   // subshell map
   nsDST*            mSubShellMap;  // map of content/subshell pairs
@@ -993,7 +1010,9 @@ PresShell::PresShell():mStackArena(nsnull),
                        mFirstDOMEventRequest(nsnull),
                        mLastDOMEventRequest(nsnull),
                        mFirstAttributeRequest(nsnull),
-                       mLastAttributeRequest(nsnull)
+                       mLastAttributeRequest(nsnull),
+                       mFirstCallbackEventRequest(nsnull),
+                       mLastCallbackEventRequest(nsnull)
 {
   NS_INIT_REFCNT();
   mIsDestroying = PR_FALSE;
@@ -1881,6 +1900,7 @@ PresShell::ResizeReflow(nscoord aWidth, nscoord aHeight)
   mViewManager->CacheWidgetChanges(PR_FALSE);
   HandlePostedDOMEvents();
   HandlePostedAttributeChanges();
+  HandlePostedReflowCallbacks();
 
   //Send resize event from here.
   nsEvent event;
@@ -3105,6 +3125,29 @@ PresShell::GetGeneratedContentIterator(nsIContent*          aContent,
   return rv;
 }
 
+// Post a request to handle an arbitrary callback after reflow has finished.
+NS_IMETHODIMP
+PresShell::PostReflowCallback(nsIReflowCallback* aCallback)
+{
+  nsCallbackEventRequest* request = nsnull;
+  void* result = nsnull;
+  AllocateFrame(sizeof(nsCallbackEventRequest), &result);
+  request = (nsCallbackEventRequest*)result;
+
+  request->callback = aCallback;
+  NS_ADDREF(aCallback);
+  request->next = nsnull;
+
+  if (mLastCallbackEventRequest) {
+    mLastCallbackEventRequest = mLastCallbackEventRequest->next = request;
+  } else {
+    mFirstCallbackEventRequest = request;
+    mLastCallbackEventRequest = request;
+  }
+ 
+  return NS_OK;
+}
+
 /**
 * Post a request to handle a DOM event after Reflow has finished.
 * The event must have been created with the "new" operator.
@@ -3175,6 +3218,28 @@ PresShell::PostAttributeChange(nsIContent* aContent,
   return NS_OK;
 }
 
+void
+PresShell::HandlePostedReflowCallbacks()
+{
+   PRBool shouldFlush = PR_FALSE;
+   nsCallbackEventRequest* node = mFirstCallbackEventRequest;
+   while(node)
+   {
+      nsIReflowCallback* callback = node->callback;
+      nsCallbackEventRequest* toFree = node;
+      node = node->next;
+      mFirstCallbackEventRequest = node;
+      FreeFrame(sizeof(nsCallbackEventRequest), toFree);
+      callback->ReflowFinished(this, &shouldFlush); 
+      NS_RELEASE(callback);
+   }
+
+   mFirstCallbackEventRequest = mLastCallbackEventRequest = nsnull;
+
+   if (shouldFlush)
+     FlushPendingNotifications();
+}
+
 void
 PresShell::HandlePostedDOMEvents()
 {
@@ -4197,6 +4262,7 @@ PresShell::ProcessReflowCommands(PRBool aInterruptible)
 
   HandlePostedDOMEvents();
   HandlePostedAttributeChanges();
+  HandlePostedReflowCallbacks();
   return NS_OK;
 }
 

layout/xul/base/src/nsIScrollbarMediator.h

@@ -38,6 +38,8 @@ public:
   
   NS_IMETHOD PositionChanged(PRInt32 aOldIndex, PRInt32 aNewIndex) = 0;
   NS_IMETHOD ScrollbarButtonPressed(PRInt32 aOldIndex, PRInt32 aNewIndex) = 0;
+
+  NS_IMETHOD VisibilityChanged(PRBool aVisible) = 0;
 };
 
 #endif

layout/xul/base/src/nsXULTreeGroupFrame.cpp

@@ -243,7 +243,9 @@ nsXULTreeGroupFrame::GetFirstTreeBox()
     mFrameConstructor->CreateTreeWidgetContent(mPresContext, this, nsnull, startContent,
                                                &mTopFrame, isAppend, PR_FALSE, 
                                                nsnull);
-    
+    if (mTopFrame)
+      mOuterFrame->PostReflowCallback();
+
     mBottomFrame = mTopFrame;
     nsCOMPtr<nsIXULTreeSlice> slice(do_QueryInterface(mTopFrame));
     PRBool isGroup = PR_FALSE;
@@ -320,6 +322,8 @@ nsXULTreeGroupFrame::GetNextTreeBox(nsIBox* aBox)
       mFrameConstructor->CreateTreeWidgetContent(mPresContext, this, prevFrame, nextContent,
                                                  &result, isAppend, PR_FALSE,
                                                  nsnull);
+      if (result)
+        mOuterFrame->PostReflowCallback();
     }
   }
 

layout/xul/base/src/nsXULTreeOuterGroupFrame.cpp

@@ -40,7 +40,6 @@
 #include "nsIDragService.h"
 #include "nsIServiceManager.h"
 
-
 #define TICK_FACTOR 50
 
 static NS_DEFINE_IID(kIFrameIID, NS_IFRAME_IID);
@@ -175,7 +174,7 @@ nsXULTreeOuterGroupFrame::nsXULTreeOuterGroupFrame(nsIPresShell* aPresShell, PRB
 :nsXULTreeGroupFrame(aPresShell, aIsRoot, aLayoutManager, aIsHorizontal),
  mRowGroupInfo(nsnull), mRowHeight(0), mCurrentIndex(0), mAutoScrollTimer(nsnull),
  mTreeIsSorted(PR_FALSE), mDragOverListener(nsnull), mCurrentlyTrackingAutoScroll(PR_FALSE),
- mTreeLayoutState(eTreeLayoutNormal)
+ mTreeLayoutState(eTreeLayoutNormal), mReflowCallbackPosted(PR_FALSE)
 {
 }
 
@@ -216,6 +215,7 @@ nsXULTreeOuterGroupFrame::Release(void)
 NS_INTERFACE_MAP_BEGIN(nsXULTreeOuterGroupFrame)
   NS_INTERFACE_MAP_ENTRY(nsIScrollbarMediator)
   NS_INTERFACE_MAP_ENTRY(nsIDragTracker)
+  NS_INTERFACE_MAP_ENTRY(nsIReflowCallback)
 NS_INTERFACE_MAP_END_INHERITING(nsXULTreeGroupFrame)
 
 
@@ -303,6 +303,8 @@ nsXULTreeOuterGroupFrame::SetRowHeight(nscoord aRowHeight)
     mTreeLayoutState = eTreeLayoutAbort;
     if (mCurrentIndex > 0)
       VerticalScroll(mCurrentIndex * mRowHeight);
+
+    PostReflowCallback();
   } 
 }
 
@@ -410,6 +412,26 @@ nsXULTreeOuterGroupFrame::ComputeTotalRowCount(PRInt32& aCount, nsIContent* aPar
   }
 }
 
+void
+nsXULTreeOuterGroupFrame::PostReflowCallback()
+{
+  if (!mReflowCallbackPosted) {
+    mReflowCallbackPosted = PR_TRUE;
+    nsCOMPtr<nsIPresShell> shell;
+    mPresContext->GetShell(getter_AddRefs(shell));
+    shell->PostReflowCallback(this);
+  }
+}
+
+NS_IMETHODIMP
+nsXULTreeOuterGroupFrame::VisibilityChanged(PRBool aVisible)
+{
+  if (!aVisible && mCurrentIndex > 0)
+    EnsureRowIsVisible(0);
+
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsXULTreeOuterGroupFrame::ScrollbarButtonPressed(PRInt32 aOldIndex, PRInt32 aNewIndex)
 {
@@ -1020,6 +1042,15 @@ nsXULTreeOuterGroupFrame::IndexOfItem(nsIContent* aRoot, nsIContent* aContent,
   return NS_ERROR_FAILURE;
 }
 
+NS_IMETHODIMP
+nsXULTreeOuterGroupFrame::ReflowFinished(nsIPresShell* aPresShell, PRBool* aFlushFlag)
+{
+  mReflowCallbackPosted = PR_FALSE;
+  nsBoxLayoutState state(mPresContext);
+  MarkDirtyChildren(state);
+  *aFlushFlag = PR_TRUE;
+  return NS_OK;
+}
 
 //
 // Paint

layout/xul/base/src/nsXULTreeOuterGroupFrame.h

@@ -36,7 +36,7 @@
 #include "nsITimerCallback.h"
 #include "nsITimer.h"
 #include "nsIDragTracker.h"
-
+#include "nsIReflowCallback.h"
 
 class nsCSSFrameConstructor;
 class nsDragOverListener;
@@ -147,7 +147,7 @@ private:
 
 
 class nsXULTreeOuterGroupFrame : public nsXULTreeGroupFrame, public nsIScrollbarMediator,
-                                    public nsIDragTracker
+                                 public nsIDragTracker, public nsIReflowCallback
 {
 public:
   NS_DECL_ISUPPORTS
@@ -164,6 +164,9 @@ public:
   NS_IMETHOD Init(nsIPresContext* aPresContext, nsIContent* aContent,
                   nsIFrame* aParent, nsIStyleContext* aContext, nsIFrame* aPrevInFlow);
 
+  // nsIReflowCallback
+  NS_IMETHOD ReflowFinished(nsIPresShell* aPresShell, PRBool* aFlushFlag);
+
 protected:
   nsXULTreeOuterGroupFrame(nsIPresShell* aPresShell, PRBool aIsRoot = nsnull, nsIBoxLayout* aLayoutManager = nsnull, PRBool aDefaultHorizontal = PR_TRUE);
   virtual ~nsXULTreeOuterGroupFrame();
@@ -207,6 +210,7 @@ public:
   
   NS_IMETHOD PositionChanged(PRInt32 aOldIndex, PRInt32 aNewIndex);
   NS_IMETHOD ScrollbarButtonPressed(PRInt32 aOldIndex, PRInt32 aNewIndex);
+  NS_IMETHOD VisibilityChanged(PRBool aVisible);
 
   void VerticalScroll(PRInt32 aDelta);
 
@@ -243,6 +247,8 @@ public:
   nsTreeLayoutState GetTreeLayoutState() { return mTreeLayoutState; }
   void SetTreeLayoutState(nsTreeLayoutState aState) { mTreeLayoutState = aState; }
 
+  void PostReflowCallback();
+
 protected: // Data Members
 
   void ComputeTotalRowCount(PRInt32& aRowCount, nsIContent* aParent);
@@ -268,7 +274,7 @@ protected: // Data Members
   nsDragOverListener* mDragOverListener;
   nsDragAutoScrollTimer* mAutoScrollTimer;      // actually a strong ref
   nsTreeLayoutState mTreeLayoutState;
-  
+  PRBool mReflowCallbackPosted;
 }; // class nsXULTreeOuterGroupFrame