Fixing Bug 454632 - Resizing tree widget always re-scrolls to current index. r=enndeakin,sr=bz. Patch by Stephen Lau <steve@grommit.com>.

content/base/src/nsGkAtomList.h

@@ -459,6 +459,7 @@ GK_ATOM(isindex, "isindex")
 GK_ATOM(ismap, "ismap")
 GK_ATOM(kbd, "kbd")
 GK_ATOM(noautofocus, "noautofocus")
+GK_ATOM(keepcurrentinview, "keepcurrentinview")
 GK_ATOM(key, "key")
 GK_ATOM(keycode, "keycode")
 GK_ATOM(keydown, "keydown")

layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp

@@ -451,6 +451,10 @@ nsTreeBodyFrame::ReflowFinished()
     if (mTopRowIndex > lastPageTopRow)
       ScrollToRowInternal(parts, lastPageTopRow);
 
+    nsIContent *treeContent = GetBaseElement();
+    if (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;
@@ -461,6 +465,7 @@ nsTreeBodyFrame::ReflowFinished()
         if (currentIndex != -1)
           EnsureRowIsVisibleInternal(parts, currentIndex);
       }
+    }
 
     if (!FullScrollbarsUpdate(PR_FALSE)) {
       return PR_FALSE;

toolkit/content/widgets/tree.xml

@@ -105,6 +105,11 @@
         true
 #endif
       </field>
+      <property name="keepCurrentInView"
+                onget="return (this.getAttribute('keepcurrentinview') == 'true');"
+                onset="if (val) this.setAttribute('keepcurrentinview', 'true');
+                       else this.removeAttribute('keepcurrentinview'); return val;"/>
+
       <property name="enableColumnDrag"
                 onget="return this.hasAttribute('enableColumnDrag');"
                 onset="if (val) this.setAttribute('enableColumnDrag', 'true');