diff --git a/content/base/src/nsGenericDOMDataNode.cpp b/content/base/src/nsGenericDOMDataNode.cpp
index f992c6d6bf9c..2cb42abe082b 100644
--- a/content/base/src/nsGenericDOMDataNode.cpp
+++ b/content/base/src/nsGenericDOMDataNode.cpp
@@ -684,9 +684,13 @@ nsGenericDOMDataNode::HandleDOMEvent(nsIPresContext* aPresContext,
   nsresult ret = NS_OK;
   nsIDOMEvent* domEvent = nsnull;
 
+  PRBool externalDOMEvent = PR_FALSE;
+    
   if (NS_EVENT_FLAG_INIT & aFlags) {
     if (!aDOMEvent) {
       aDOMEvent = &domEvent;
+    } else {
+      externalDOMEvent = PR_TRUE;
     }
     aEvent->flags = aFlags;
     aFlags &= ~(NS_EVENT_FLAG_CANT_BUBBLE | NS_EVENT_FLAG_CANT_CANCEL);
@@ -723,7 +727,7 @@ nsGenericDOMDataNode::HandleDOMEvent(nsIPresContext* aPresContext,
   if (NS_EVENT_FLAG_INIT & aFlags) {
     // We're leaving the DOM event loop so if we created a DOM event,
     // release here.
-    if (nsnull != *aDOMEvent) {
+    if (!externalDOMEvent && nsnull != *aDOMEvent) {
       if (0 != (*aDOMEvent)->Release()) {
         // Okay, so someone in the DOM loop (a listener, JS object)
         // still has a ref to the DOM Event but the internal data
diff --git a/content/base/src/nsGenericElement.cpp b/content/base/src/nsGenericElement.cpp
index 1e173a8dd93d..e7c6e7bec981 100644
--- a/content/base/src/nsGenericElement.cpp
+++ b/content/base/src/nsGenericElement.cpp
@@ -1071,6 +1071,7 @@ nsGenericElement::InternalIsSupported(const nsAReadableString& aFeature,
              feature.EqualsWithConversion("Events", PR_TRUE) ||
 //           feature.EqualsWithConversion("UIEvents", PR_TRUE) ||
              feature.EqualsWithConversion("MouseEvents", PR_TRUE) ||
+             feature.EqualsWithConversion("MouseScrollEvents", PR_TRUE) ||
              feature.EqualsWithConversion("HTMLEvents", PR_TRUE) ||
              feature.EqualsWithConversion("Range", PR_TRUE)) {
     if (!aVersion.Length() || aVersion.Equals(NS_LITERAL_STRING("2.0"))) {
diff --git a/content/events/src/nsDOMEvent.cpp b/content/events/src/nsDOMEvent.cpp
index 793fac21ed6c..d094061d464d 100644
--- a/content/events/src/nsDOMEvent.cpp
+++ b/content/events/src/nsDOMEvent.cpp
@@ -166,6 +166,10 @@ nsDOMEvent::nsDOMEvent(nsIPresContext* aPresContext, nsEvent* aEvent,
       mEvent = PR_NEWZAP(nsMouseEvent);
       mEvent->eventStructType = NS_MOUSE_EVENT;
     }
+    else if (eventType.EqualsIgnoreCase("MouseScrollEvents")) {
+      mEvent = PR_NEWZAP(nsMouseScrollEvent);
+      mEvent->eventStructType = NS_MOUSE_SCROLL_EVENT;
+    }
     else if (eventType.EqualsIgnoreCase("KeyEvents")) {
       mEvent = PR_NEWZAP(nsKeyEvent);
       mEvent->eventStructType = NS_KEY_EVENT;
@@ -506,6 +510,7 @@ nsDOMEvent::GetDetail(PRInt32* aDetail)
       case NS_MOUSE_RIGHT_BUTTON_DOWN:
       case NS_MOUSE_RIGHT_CLICK:
       case NS_MOUSE_RIGHT_DOUBLECLICK:
+      case NS_USER_DEFINED_EVENT:
         *aDetail = ((nsMouseEvent*)mEvent)->clickCount;
         break;
       default:
@@ -514,6 +519,12 @@ nsDOMEvent::GetDetail(PRInt32* aDetail)
       return NS_OK;
     }
 
+    case NS_MOUSE_SCROLL_EVENT:
+    {
+      *aDetail = ((nsMouseScrollEvent*)mEvent)->delta;
+      break;
+    }
+
     default:
       *aDetail = 0;
       return NS_OK;
@@ -1212,7 +1223,7 @@ nsDOMEvent::InitUIEvent(const nsAReadableString& aTypeArg, PRBool aCanBubbleArg,
 
 NS_IMETHODIMP
 nsDOMEvent::InitMouseEvent(const nsAReadableString & aTypeArg, PRBool aCanBubbleArg, PRBool aCancelableArg, 
-                           nsIDOMAbstractView *aViewArg, PRUint16 aDetailArg, PRInt32 aScreenXArg, 
+                           nsIDOMAbstractView *aViewArg, PRInt32 aDetailArg, PRInt32 aScreenXArg, 
                            PRInt32 aScreenYArg, PRInt32 aClientXArg, PRInt32 aClientYArg, 
                            PRBool aCtrlKeyArg, PRBool aAltKeyArg, PRBool aShiftKeyArg, 
                            PRBool aMetaKeyArg, PRUint16 aButtonArg, nsIDOMEventTarget *aRelatedTargetArg)
@@ -1221,22 +1232,28 @@ nsDOMEvent::InitMouseEvent(const nsAReadableString & aTypeArg, PRBool aCanBubble
   mEvent->flags |= aCanBubbleArg ? NS_EVENT_FLAG_NONE : NS_EVENT_FLAG_CANT_BUBBLE;
   mEvent->flags |= aCancelableArg ? NS_EVENT_FLAG_NONE : NS_EVENT_FLAG_CANT_CANCEL;
 
-  if (mEvent->eventStructType == NS_MOUSE_EVENT) {
-    nsMouseEvent* mouseEvent = NS_STATIC_CAST(nsMouseEvent*, mEvent);
-    mouseEvent->isControl = aCtrlKeyArg;
-    mouseEvent->isAlt = aAltKeyArg;
-    mouseEvent->isShift = aShiftKeyArg;
-    mouseEvent->isMeta = aMetaKeyArg;
-    mouseEvent->point.x = aClientXArg;
-    mouseEvent->point.y = aClientYArg;
-    mouseEvent->refPoint.x = aScreenXArg;
-    mouseEvent->refPoint.y = aScreenYArg;
+  if (mEvent->eventStructType == NS_MOUSE_EVENT || mEvent->eventStructType == NS_MOUSE_SCROLL_EVENT) {
+    nsInputEvent* inputEvent = NS_STATIC_CAST(nsInputEvent*, mEvent);
+    inputEvent->isControl = aCtrlKeyArg;
+    inputEvent->isAlt = aAltKeyArg;
+    inputEvent->isShift = aShiftKeyArg;
+    inputEvent->isMeta = aMetaKeyArg;
+    inputEvent->point.x = aClientXArg;
+    inputEvent->point.y = aClientYArg;
+    inputEvent->refPoint.x = aScreenXArg;
+    inputEvent->refPoint.y = aScreenYArg;
     mScreenPoint.x = aScreenXArg;
     mScreenPoint.y = aScreenYArg;
     mClientPoint.x = aClientXArg;
     mClientPoint.y = aClientYArg;
     mButton = aButtonArg;
-    mouseEvent->clickCount = aDetailArg;
+    if (mEvent->eventStructType == NS_MOUSE_SCROLL_EVENT) {
+      nsMouseScrollEvent* scrollEvent = NS_STATIC_CAST(nsMouseScrollEvent*, mEvent);
+      scrollEvent->delta = aDetailArg;
+    } else {
+      nsMouseEvent* mouseEvent = NS_STATIC_CAST(nsMouseEvent*, mEvent);
+      mouseEvent->clickCount = aDetailArg;
+    }
   }
   //include a way to set view once we have more than one
 
diff --git a/content/events/src/nsDOMEvent.h b/content/events/src/nsDOMEvent.h
index 449681df5cb6..2f652be01ca1 100644
--- a/content/events/src/nsDOMEvent.h
+++ b/content/events/src/nsDOMEvent.h
@@ -161,7 +161,7 @@ public:
   NS_IMETHOD    GetKeyCode(PRUint32* aKeyCode);
   NS_IMETHOD    InitMouseEvent(const nsAReadableString & aTypeArg, 
                                PRBool aCanBubbleArg, PRBool aCancelableArg, 
-                               nsIDOMAbstractView *aViewArg, PRUint16 aDetailArg, 
+                               nsIDOMAbstractView *aViewArg, PRInt32 aDetailArg, 
                                PRInt32 aScreenXArg, PRInt32 aDcreenYArg, 
                                PRInt32 aClientXArg, PRInt32 aClientYArg, 
                                PRBool aCtrlKeyArg, PRBool aAltKeyArg, 
diff --git a/content/events/src/nsEventListenerManager.cpp b/content/events/src/nsEventListenerManager.cpp
index bfcf4df00e58..44d28b4125e2 100644
--- a/content/events/src/nsEventListenerManager.cpp
+++ b/content/events/src/nsEventListenerManager.cpp
@@ -2342,7 +2342,7 @@ nsEventListenerManager::CreateEvent(nsIPresContext* aPresContext,
   nsAutoString str(aEventType);
   if (!aEvent && !str.EqualsIgnoreCase("MouseEvents") && !str.EqualsIgnoreCase("KeyEvents") &&
       !str.EqualsIgnoreCase("HTMLEvents") && !str.EqualsIgnoreCase("MutationEvents") &&
-      !str.EqualsIgnoreCase("Events")) {
+      !str.EqualsIgnoreCase("MouseScrollEvents") && !str.EqualsIgnoreCase("Events")) {
     return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
   }
 
diff --git a/content/events/src/nsEventStateManager.cpp b/content/events/src/nsEventStateManager.cpp
index 80d4a7d7c8de..502ccd50aad4 100644
--- a/content/events/src/nsEventStateManager.cpp
+++ b/content/events/src/nsEventStateManager.cpp
@@ -93,6 +93,12 @@
 #include "nsIOutlinerBoxObject.h"
 #include "nsIScrollableViewProvider.h"
 #include "nsIDOMDocumentRange.h"
+#include "nsIDOMDocumentEvent.h"
+#include "nsIDOMMouseEvent.h"
+#include "nsIDOMEventTarget.h"
+#include "nsIDOMDocumentView.h"
+#include "nsIDOMAbstractView.h"
+#include "nsIDOMNSUIEvent.h"
 
 #include "nsIDOMRange.h"
 #include "nsICaret.h"
@@ -1200,63 +1206,6 @@ nsEventStateManager::ChangeTextSize(PRInt32 change)
 
 
 //
-// DoTreeScroll
-//
-// Trees know best how to deal with scrolling, so use the tree scroll api's instead
-// of just blindly scrolling the view.
-//
-nsresult
-nsEventStateManager::DoTreeScroll(nsIPresContext* inPresContext, PRInt32 inNumLines,
-                                    PRBool inScrollPage, nsITreeFrame* inTreeFrame)
-{
-  PRInt32 scrollIndex, visibleRows;
-  inTreeFrame->GetIndexOfFirstVisibleRow(&scrollIndex);
-  inTreeFrame->GetNumberOfVisibleRows(&visibleRows);
-
-  if (inScrollPage)
-    scrollIndex += ((inNumLines > 0) ? visibleRows : -visibleRows);
-  else
-    scrollIndex += inNumLines;
-  
-  if (scrollIndex < 0)
-    scrollIndex = 0;
-  else {
-    PRInt32 numRows;
-    inTreeFrame->GetRowCount(&numRows);
-    PRInt32 lastPageTopRow = numRows - visibleRows;
-    if (scrollIndex > lastPageTopRow)
-      scrollIndex = lastPageTopRow;
-  }
-  
-  inTreeFrame->ScrollToIndex(scrollIndex);
-
-  // we have to do a sync update for mac because if we scroll too quickly
-  // w/out going back to the main event loop we can easily scroll the wrong
-  // bits and it looks like garbage (bug 63465).
-  nsIFrame* frame = nsnull;
-  if ( NS_SUCCEEDED(inTreeFrame->QueryInterface(NS_GET_IID(nsIFrame),
-                                                (void **)&frame)) ) {
-    nsIView* treeView = nsnull;
-    frame->GetView(inPresContext, &treeView);
-    if (!treeView) {
-      nsIFrame* frameWithView;
-      frame->GetParentWithView(inPresContext, &frameWithView);
-      if (frameWithView)
-        frameWithView->GetView(inPresContext, &treeView);
-      else
-        return NS_ERROR_FAILURE;
-    }
-    if (treeView)
-      ForceViewUpdate(treeView);
-  }
-  else
-    return NS_ERROR_FAILURE;
-     
-  return NS_OK;
-      
-} // DoTreeScroll
-
-
 nsresult
 nsEventStateManager::DoWheelScroll(nsIPresContext* aPresContext,
                                    nsIFrame* aTargetFrame,
@@ -1264,27 +1213,50 @@ nsEventStateManager::DoWheelScroll(nsIPresContext* aPresContext,
                                    PRInt32 numLines, PRBool scrollPage,
                                    PRBool aUseTargetFrame)
 {
+  nsCOMPtr<nsIContent> targetContent;
+  aTargetFrame->GetContent(getter_AddRefs(targetContent));
+
+  nsCOMPtr<nsIDocument> targetDoc;
+  targetContent->GetDocument(*getter_AddRefs(targetDoc));
+  if (!targetDoc) return NS_OK;
+  nsCOMPtr<nsIDOMDocumentEvent> targetDOMDoc(do_QueryInterface(targetDoc));
+
+  nsCOMPtr<nsIDOMEvent> event;
+  targetDOMDoc->CreateEvent(NS_LITERAL_STRING("MouseScrollEvents"), getter_AddRefs(event));
+  if (event) {
+    nsCOMPtr<nsIDOMMouseEvent> mouseEvent(do_QueryInterface(event));
+    nsCOMPtr<nsIDOMDocumentView> docView = do_QueryInterface(targetDoc);
+    if (!docView) return nsnull;
+    nsCOMPtr<nsIDOMAbstractView> view;
+    docView->GetDefaultView(getter_AddRefs(view));
+    
+    if (scrollPage)
+      numLines = numLines > 0 ? nsIDOMNSUIEvent::SCROLL_PAGE_DOWN : nsIDOMNSUIEvent::SCROLL_PAGE_UP;
+      
+    mouseEvent->InitMouseEvent(NS_LITERAL_STRING("DOMMouseScroll"), PR_TRUE, PR_TRUE, 
+                               view, numLines,
+                               msEvent->refPoint.x, msEvent->refPoint.y,
+                               msEvent->point.x, msEvent->point.y,
+                               msEvent->isControl, msEvent->isAlt, msEvent->isShift, msEvent->isMeta,
+                               0, nsnull);
+    PRBool allowDefault;
+    nsCOMPtr<nsIDOMEventTarget> target(do_QueryInterface(targetContent));
+    if (target) {
+      target->DispatchEvent(event, &allowDefault);
+      if (!allowDefault)
+        return NS_OK;
+    }
+  }
+
+  targetDOMDoc->CreateEvent(NS_LITERAL_STRING("MouseScrollEvents"), getter_AddRefs(event));
+  if (event) {
+    nsCOMPtr<nsIDOMMouseEvent> mouseEvent(do_QueryInterface(event));
+  }
+
   nsIView* focusView = nsnull;
   nsIScrollableView* sv = nsnull;
   nsIFrame* focusFrame = nsnull;
   
-  // Special case for tree/list frames - they handle their own scrolling
-  nsITreeFrame* treeFrame = nsnull;
-  nsCOMPtr<nsIOutlinerBoxObject> outlinerBoxObject;
-  nsIFrame* curFrame = aTargetFrame;
-  
-  while (curFrame) {
-    if (NS_OK == curFrame->QueryInterface(NS_GET_IID(nsITreeFrame),
-                                          (void**) &treeFrame))
-      break;
-
-    outlinerBoxObject = do_QueryInterface(curFrame);
-    if (outlinerBoxObject)
-      break;
-
-    curFrame->GetParent(&curFrame);
-  }
-  
   // Create a mouseout event that we fire to the content before
   // scrolling, to allow tooltips to disappear, etc.
 
@@ -1300,27 +1272,8 @@ nsEventStateManager::DoWheelScroll(nsIPresContext* aPresContext,
   mouseOutEvent.isAlt = PR_FALSE;
   mouseOutEvent.isMeta = PR_FALSE;
 
-  nsCOMPtr<nsIContent> targetContent;
-  aTargetFrame->GetContent(getter_AddRefs(targetContent));
-
   nsEventStatus mouseoutStatus = nsEventStatus_eIgnore;
 
-  if (treeFrame) {
-    if (targetContent)
-      targetContent->HandleDOMEvent(aPresContext, &mouseOutEvent, nsnull,
-                                    NS_EVENT_FLAG_INIT, &mouseoutStatus);
-    return DoTreeScroll(aPresContext, numLines, scrollPage, treeFrame);
-  } else if (outlinerBoxObject) {
-    if (targetContent)
-      targetContent->HandleDOMEvent(aPresContext, &mouseOutEvent, nsnull,
-                                    NS_EVENT_FLAG_INIT, &mouseoutStatus);
-    if (scrollPage)
-      outlinerBoxObject->ScrollByPages((numLines > 0) ? 1 : -1);
-    else
-      outlinerBoxObject->ScrollByLines(numLines);
-    return NS_OK;
-  }
-  
   nsCOMPtr<nsIPresShell> presShell;
   aPresContext->GetShell(getter_AddRefs(presShell));
 
diff --git a/content/events/src/nsEventStateManager.h b/content/events/src/nsEventStateManager.h
index 9d765c5a4ace..586d87764270 100644
--- a/content/events/src/nsEventStateManager.h
+++ b/content/events/src/nsEventStateManager.h
@@ -174,8 +174,6 @@ protected:
                          nsIFrame* aTargetFrame,
                          nsMouseScrollEvent* msEvent, PRInt32 numLines,
                          PRBool scrollPage, PRBool aUseTargetFrame);
-  nsresult DoTreeScroll(nsIPresContext* inPresContext, PRInt32 inNumLines,
-                         PRBool inScrollPage, nsITreeFrame* inTreeFrame);
   void ForceViewUpdate(nsIView* aView);
   nsresult getPrefService();
   nsresult ChangeTextSize(PRInt32 change);
diff --git a/content/xul/document/src/nsXULDocument.cpp b/content/xul/document/src/nsXULDocument.cpp
index cf0daf2194ce..184d5283d77d 100644
--- a/content/xul/document/src/nsXULDocument.cpp
+++ b/content/xul/document/src/nsXULDocument.cpp
@@ -2388,9 +2388,17 @@ nsXULDocument::HandleDOMEvent(nsIPresContext* aPresContext,
 {
   nsresult ret = NS_OK;
   nsIDOMEvent* domEvent = nsnull;
+  PRBool externalDOMEvent = PR_FALSE;
 
   if (NS_EVENT_FLAG_INIT & aFlags) {
-    aDOMEvent = &domEvent;
+    if (aDOMEvent) {
+      if (*aDOMEvent) {
+        externalDOMEvent = PR_TRUE;   
+      }
+    }
+    else {
+      aDOMEvent = &domEvent;
+    }
     aEvent->flags = aFlags;
     aFlags &= ~(NS_EVENT_FLAG_CANT_BUBBLE | NS_EVENT_FLAG_CANT_CANCEL);
   }
@@ -2414,7 +2422,7 @@ nsXULDocument::HandleDOMEvent(nsIPresContext* aPresContext,
 
   if (NS_EVENT_FLAG_INIT & aFlags) {
     // We're leaving the DOM event loop so if we created a DOM event, release here.
-    if (nsnull != *aDOMEvent) {
+    if (nsnull != *aDOMEvent && !externalDOMEvent) {
       nsrefcnt rc;
       NS_RELEASE2(*aDOMEvent, rc);
       if (0 != rc) {
diff --git a/dom/public/idl/events/nsIDOMMouseEvent.idl b/dom/public/idl/events/nsIDOMMouseEvent.idl
index fb374937378b..40ad2923c300 100644
--- a/dom/public/idl/events/nsIDOMMouseEvent.idl
+++ b/dom/public/idl/events/nsIDOMMouseEvent.idl
@@ -61,7 +61,7 @@ interface nsIDOMMouseEvent : nsIDOMUIEvent
 										                       in boolean canBubbleArg,
   										                     in boolean cancelableArg,
                                            in nsIDOMAbstractView viewArg,
-                                           in unsigned short detailArg,
+                                           in long detailArg,
                                            in long screenXArg,
                                            in long screenYArg,
                                            in long clientXArg,
diff --git a/dom/public/idl/events/nsIDOMNSUIEvent.idl b/dom/public/idl/events/nsIDOMNSUIEvent.idl
index 5c0a5f3f848f..37fd23aa1903 100644
--- a/dom/public/idl/events/nsIDOMNSUIEvent.idl
+++ b/dom/public/idl/events/nsIDOMNSUIEvent.idl
@@ -43,6 +43,9 @@
 [scriptable, uuid(a6cf90c4-15b3-11d2-932e-00805f8add32)]
 interface nsIDOMNSUIEvent : nsISupports
 {
+  const long SCROLL_PAGE_UP = -32768;
+  const long SCROLL_PAGE_DOWN = 32768;
+
   boolean                   getPreventDefault();
 
   readonly attribute long             layerX;
diff --git a/layout/xul/base/public/nsITreeBoxObject.idl b/layout/xul/base/public/nsITreeBoxObject.idl
index aaa29fdef998..b548c80e6df6 100644
--- a/layout/xul/base/public/nsITreeBoxObject.idl
+++ b/layout/xul/base/public/nsITreeBoxObject.idl
@@ -46,6 +46,7 @@ interface nsITreeBoxObject : nsISupports
 {
   void ensureIndexIsVisible(in long rowIndex);
   void scrollToIndex(in long rowIndex);
+  void scrollByLines(in long numLines);
 
   nsIDOMElement getNextItem(in nsIDOMElement startItem, in long delta);
   nsIDOMElement getPreviousItem(in nsIDOMElement startItem, in long delta);
diff --git a/layout/xul/base/public/nsITreeFrame.h b/layout/xul/base/public/nsITreeFrame.h
index 04c347519e8e..e52d5c7bdc8a 100644
--- a/layout/xul/base/public/nsITreeFrame.h
+++ b/layout/xul/base/public/nsITreeFrame.h
@@ -57,6 +57,7 @@ public:
   NS_IMETHOD GetNextItem(nsIDOMElement* aStartItem, PRInt32 aDelta, nsIDOMElement** aResult) = 0;
   NS_IMETHOD GetPreviousItem(nsIDOMElement* aStartItem, PRInt32 aDelta, nsIDOMElement** aResult) = 0;
   NS_IMETHOD ScrollToIndex(PRInt32 aRowIndex) = 0;
+  NS_IMETHOD ScrollByLines(nsIPresContext* aPresContext, PRInt32 aNumLines)=0;
   NS_IMETHOD GetItemAtIndex(PRInt32 aIndex, nsIDOMElement** aResult) = 0;
   NS_IMETHOD GetIndexOfItem(nsIPresContext* aPresContext, nsIDOMElement* aElement, PRInt32* aResult) = 0;
   NS_IMETHOD GetNumberOfVisibleRows(PRInt32* aResult) = 0;
diff --git a/layout/xul/base/src/nsTreeBoxObject.cpp b/layout/xul/base/src/nsTreeBoxObject.cpp
index b524db18e0e5..e71ec317c47c 100644
--- a/layout/xul/base/src/nsTreeBoxObject.cpp
+++ b/layout/xul/base/src/nsTreeBoxObject.cpp
@@ -110,6 +110,19 @@ NS_IMETHODIMP nsTreeBoxObject::ScrollToIndex(PRInt32 aRowIndex)
   return treeFrame->ScrollToIndex(aRowIndex);
 }
 
+NS_IMETHODIMP
+nsTreeBoxObject::ScrollByLines(PRInt32 aNumLines)
+{
+  nsIFrame* frame = GetFrame();
+  if (!frame)
+    return NS_OK;
+  
+  nsCOMPtr<nsITreeFrame> treeFrame(do_QueryInterface(frame));
+  nsCOMPtr<nsIPresContext> presContext;
+  mPresShell->GetPresContext(getter_AddRefs(presContext));
+  return treeFrame->ScrollByLines(presContext, aNumLines);
+}
+
 /* nsIDOMElement getNextItem (in nsIDOMElement startItem, in long delta); */
 NS_IMETHODIMP nsTreeBoxObject::GetNextItem(nsIDOMElement *aStartItem, PRInt32 aDelta, nsIDOMElement **aResult)
 {
diff --git a/layout/xul/base/src/nsXULTreeFrame.cpp b/layout/xul/base/src/nsXULTreeFrame.cpp
index 6a49a9f0987e..e13c8922a616 100644
--- a/layout/xul/base/src/nsXULTreeFrame.cpp
+++ b/layout/xul/base/src/nsXULTreeFrame.cpp
@@ -154,6 +154,58 @@ nsXULTreeFrame::ScrollToIndex(PRInt32 aRowIndex)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsXULTreeFrame::ScrollByLines(nsIPresContext* aPresContext, PRInt32 aNumLines)
+{
+  PRInt32 scrollIndex, visibleRows;
+  GetIndexOfFirstVisibleRow(&scrollIndex);
+  GetNumberOfVisibleRows(&visibleRows);
+
+  scrollIndex += aNumLines;
+  
+  if (scrollIndex < 0)
+    scrollIndex = 0;
+  else {
+    PRInt32 numRows;
+    GetRowCount(&numRows);
+    PRInt32 lastPageTopRow = numRows - visibleRows;
+    if (scrollIndex > lastPageTopRow)
+      scrollIndex = lastPageTopRow;
+  }
+  
+  ScrollToIndex(scrollIndex);
+
+  // we have to do a sync update for mac because if we scroll too quickly
+  // w/out going back to the main event loop we can easily scroll the wrong
+  // bits and it looks like garbage (bug 63465).
+  nsIFrame* frame = nsnull;
+  if ( NS_SUCCEEDED(QueryInterface(NS_GET_IID(nsIFrame), (void **)&frame)) ) {
+    nsIView* treeView = nsnull;
+    frame->GetView(aPresContext, &treeView);
+    if (!treeView) {
+      nsIFrame* frameWithView;
+      frame->GetParentWithView(aPresContext, &frameWithView);
+      if (frameWithView)
+        frameWithView->GetView(aPresContext, &treeView);
+      else
+        return NS_ERROR_FAILURE;
+    }
+    if (treeView) {
+      nsCOMPtr<nsIViewManager> vm;
+      if (treeView->GetViewManager(*getter_AddRefs(vm)) && nsnull != vm) {
+        // I'd use Composite here, but it doesn't always work.
+        // vm->Composite();
+        vm->ForceUpdate();
+    
+      }      
+    }
+  }
+  else
+    return NS_ERROR_FAILURE;
+     
+  return NS_OK;
+}
+
 /* nsIDOMElement getNextItem (in nsIDOMElement startItem, in long delta); */
 NS_IMETHODIMP 
 nsXULTreeFrame::GetNextItem(nsIDOMElement *aStartItem, PRInt32 aDelta, nsIDOMElement **aResult)
diff --git a/layout/xul/base/src/nsXULTreeFrame.h b/layout/xul/base/src/nsXULTreeFrame.h
index fc68e5319a90..457b032233cf 100644
--- a/layout/xul/base/src/nsXULTreeFrame.h
+++ b/layout/xul/base/src/nsXULTreeFrame.h
@@ -59,6 +59,7 @@ public:
   NS_IMETHOD GetNextItem(nsIDOMElement* aStartItem, PRInt32 aDelta, nsIDOMElement** aResult);
   NS_IMETHOD GetPreviousItem(nsIDOMElement* aStartItem, PRInt32 aDelta, nsIDOMElement** aResult);
   NS_IMETHOD ScrollToIndex(PRInt32 aRowIndex);
+  NS_IMETHOD ScrollByLines(nsIPresContext* aPresContext, PRInt32 aNumLines);
   NS_IMETHOD GetItemAtIndex(PRInt32 aIndex, nsIDOMElement** aResult);
   NS_IMETHOD GetIndexOfItem(nsIPresContext* aPresContext, nsIDOMElement* aElement, PRInt32* aResult);
   NS_IMETHOD GetNumberOfVisibleRows(PRInt32 *aResult);
diff --git a/xpfe/global/resources/content/bindings/outliner.xml b/xpfe/global/resources/content/bindings/outliner.xml
index 17ef605df5a9..d6edd47f5f70 100644
--- a/xpfe/global/resources/content/bindings/outliner.xml
+++ b/xpfe/global/resources/content/bindings/outliner.xml
@@ -23,6 +23,10 @@
     </content>
     
     <implementation>
+      <constructor>
+        this.addEventListener("DOMMouseScroll", this._handleMouseScroll, true);
+      </constructor>
+
       <property name="outlinerBoxObject"
                 onget="return this.boxObject.QueryInterface(Components.interfaces.nsIOutlinerBoxObject);"
                 readonly="true"/>
@@ -58,6 +62,24 @@
       
       <field name="_columnsDirty">true</field>
 
+      <field name="_handleMouseScroll">
+      <![CDATA[
+        ({
+          subject: this,
+          handleEvent: function(aEvent)
+          {
+            var rows = aEvent.detail;
+            if (rows == NSUIEvent.SCROLL_PAGE_UP)
+              this.subject.outlinerBoxObject.scrollByPages(-1);
+            else if (rows == NSUIEvent.SCROLL_PAGE_DOWN)
+              this.subject.outlinerBoxObject.scrollByPages(1);
+            else
+              this.subject.outlinerBoxObject.scrollByLines(aEvent.detail);
+          }
+        })
+      ]]>
+      </field>
+
       <method name="_ensureColumnOrder">
         <body><![CDATA[
           if (this._columnsDirty) {
diff --git a/xpfe/global/resources/content/bindings/tree.xml b/xpfe/global/resources/content/bindings/tree.xml
index 001407380577..574077fdffd7 100644
--- a/xpfe/global/resources/content/bindings/tree.xml
+++ b/xpfe/global/resources/content/bindings/tree.xml
@@ -284,6 +284,31 @@
   <binding id="treerows"
            extends="chrome://global/content/bindings/tree.xml#tree-base">
     <content outer="true"/>
+    <implementation>
+      <constructor>
+        this.addEventListener("DOMMouseScroll", this._handleMouseScroll, true);
+      </constructor>
+
+      <field name="_handleMouseScroll">
+      <![CDATA[
+        ({
+          subject: this,
+          handleEvent: function(aEvent)
+          {
+            var treeBox = this.subject.parentNode.treeBoxObject;
+            var rows = aEvent.detail;
+            if (rows == NSUIEvent.SCROLL_PAGE_UP)
+              rows = -1 * treeBox.getNumberOfVisibleRows();
+            else if (rows == NSUIEvent.SCROLL_PAGE_DOWN)
+              rows = treeBox.getNumberOfVisibleRows();
+
+            treeBox.scrollByLines(rows);
+          }
+        })
+      ]]>
+      </field>
+    </implementation>
+
     <handlers>
       <!-- If there is no modifier key, we select on mousedown, not
            click, so that drags work correctly. -->