Fix for bug #20452. r=pav

layout/xul/base/src/nsBoxFrame.cpp

@@ -41,10 +41,12 @@
 #include "nsSpaceManager.h"
 #include "nsHTMLParts.h"
 #include "nsIViewManager.h"
+#include "nsIView.h"
 #include "nsIPresShell.h"
 #include "nsGenericHTMLElement.h"
 #include "nsFrameNavigator.h"
 #include "nsCSSRendering.h"
+#include "nsISelfScrollingFrame.h"
 
 #define CONSTANT 0
 #define DEBUG_REFLOW 0
@@ -882,7 +884,15 @@ nsBoxFrame::CollapseChild(nsIPresContext* aPresContext, nsIFrame* frame, PRBool
            return;
          }
       }
-    
+
+      // Trees have to collapse their scrollbars manually, since you can't
+      // get to the scrollbar via the normal frame list.
+      nsISelfScrollingFrame* treeFrame;
+      if (NS_SUCCEEDED(frame->QueryInterface(nsISelfScrollingFrame::GetIID(), (void**)&treeFrame)) && treeFrame) {
+        // Tell the tree frame to collapse its scrollbar.
+        treeFrame->CollapseScrollbar(aPresContext, hide);
+      }
+      
       // collapse the child
       nsIFrame* child = nsnull;
       frame->FirstChild(nsnull, &child);

layout/xul/base/src/nsTreeFrame.cpp

@@ -617,6 +617,22 @@ nsTreeFrame::ScrollByLines(nsIPresContext* aPresContext, PRInt32 lines)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsTreeFrame::CollapseScrollbar(nsIPresContext* aPresContext, PRBool aHide)
+{
+  // Get our treechildren child frame.
+  nsTreeRowGroupFrame* treeRowGroup = nsnull;
+  GetTreeBody(&treeRowGroup);
+  
+  if (!treeRowGroup)
+    return NS_OK; // No tree body. Just bail.
+
+  treeRowGroup->CollapseScrollbar(aHide, aPresContext, nsnull);
+
+  return NS_OK;
+}
+
+
 NS_IMETHODIMP
 nsTreeFrame::EnsureRowIsVisible(PRInt32 aRowIndex)
 {

layout/xul/base/src/nsTreeFrame.h

@@ -94,6 +94,7 @@ public:
 
   // nsISelfScrollingFrame interface
   NS_IMETHOD ScrollByLines(nsIPresContext* aPresContext, PRInt32 lines);
+  NS_IMETHOD CollapseScrollbar(nsIPresContext* aPresContext, PRBool aHide);
 
   // nsITreeFrame.h
   NS_IMETHOD EnsureRowIsVisible(PRInt32 aRowIndex);

layout/xul/base/src/nsTreeOuterFrame.cpp

@@ -225,4 +225,25 @@ nsTreeOuterFrame::ScrollByLines(nsIPresContext* aPresContext, PRInt32 lines)
   return NS_ERROR_FAILURE;
 }
 
+NS_IMETHODIMP
+nsTreeOuterFrame::CollapseScrollbar(nsIPresContext* aPresContext, PRBool aHide)
+{
+  // What we need to do is call the corresponding method on our TreeFrame
+  // In most cases the TreeFrame will be the only child, but just to make
+  // sure we'll check for the right interface
+
+  nsISelfScrollingFrame* sf;
+  nsIFrame* child;
+  FirstChild(NULL, &child);
+
+  while (child != nsnull) {
+    if (NS_OK == child->QueryInterface(NS_GET_IID(nsISelfScrollingFrame),
+                                       (void**)&sf)) {
+      return sf->CollapseScrollbar(aPresContext, aHide);
+    }
+    child->GetNextSibling(&child);
+  }
+
+  return NS_ERROR_FAILURE;
+}
 

layout/xul/base/src/nsTreeOuterFrame.h

@@ -53,6 +53,7 @@ public:
                                nsHTMLReflowState& aChildReflowState);
 
   NS_IMETHOD ScrollByLines(nsIPresContext* aPresContext, PRInt32 lines);
+  NS_IMETHOD CollapseScrollbar(nsIPresContext* aPresContext, PRBool aHide);
 
 protected:
   nsTreeOuterFrame();

layout/xul/base/src/nsTreeRowGroupFrame.cpp

@@ -47,6 +47,8 @@
 #include "nsIDOMDragListener.h"
 #include "nsTreeItemDragCapturer.h"
 #include "nsLayoutAtoms.h"
+#include "nsIViewManager.h"
+#include "nsIView.h"
 
 // I added the following function to improve keeping the frame 
 // chains in synch with the table. repackage as appropriate - karnaze
@@ -1624,6 +1626,50 @@ void nsTreeRowGroupFrame::CreateScrollbar(nsIPresContext* aPresContext)
   }
 }
 
+void
+nsTreeRowGroupFrame::CollapseScrollbar(PRBool hide, nsIPresContext* aPresContext, nsIFrame* aFrame)
+{
+  nsIFrame* frame = aFrame;
+  if (frame == nsnull)
+    frame = mScrollbar;
+
+  if (frame == nsnull)
+    return;
+
+  // shrink the view
+  nsIView* view = nsnull;
+  frame->GetView(aPresContext, &view);
+
+  // if we find a view stop right here. All views under it
+  // will be clipped.
+  if (view) {
+     nsViewVisibility v;
+     view->GetVisibility(v);
+     nsCOMPtr<nsIWidget> widget;
+     view->GetWidget(*getter_AddRefs(widget));
+     if (hide) {
+         view->SetVisibility(nsViewVisibility_kHide);
+     } else {
+         view->SetVisibility(nsViewVisibility_kShow);
+     }
+     if (widget) {
+
+       return;
+     }
+  }
+
+  // collapse the child
+  nsIFrame* child = nsnull;
+  frame->FirstChild(nsnull, &child);
+
+  while (nsnull != child) 
+  {
+     CollapseScrollbar(hide, aPresContext, child);
+     nsresult rv = child->GetNextSibling(&child);
+     NS_ASSERTION(rv == NS_OK,"failed to get next child");
+  }
+}
+
 void
 nsTreeRowGroupFrame::IndexOfCell(nsIPresContext* aPresContext,
                                  nsIContent* aCellContent, PRInt32& aRowIndex, PRInt32& aColIndex)

layout/xul/base/src/nsTreeRowGroupFrame.h

@@ -50,6 +50,7 @@ public:
   void SetFrameConstructor(nsCSSFrameConstructor* aFrameConstructor) { mFrameConstructor = aFrameConstructor; };
   
   void CreateScrollbar(nsIPresContext* aPresContext);
+  void CollapseScrollbar(PRBool aHide, nsIPresContext* aPresContext, nsIFrame* aCurrentFrame);
 
   NS_IMETHOD  TreeAppendFrames(nsIFrame*       aFrameList);