diff --git a/mozilla/layout/xul/base/src/nsListBoxLayout.cpp b/mozilla/layout/xul/base/src/nsListBoxLayout.cpp
index e9bbf9e07e6..f6a2e8211e8 100644
--- a/mozilla/layout/xul/base/src/nsListBoxLayout.cpp
+++ b/mozilla/layout/xul/base/src/nsListBoxLayout.cpp
@@ -212,10 +212,12 @@ nsListBoxLayout::LayoutInternal(nsIBox* aBox, nsBoxLayoutState& aState)
     box->HasDirtyChildren(dirtyChildren);
        
     nsRect childRect;
+    box->GetBounds(childRect);
     box->GetMargin(margin);
     
     // relayout if we must or we are dirty or some of our children are dirty
-    if (relayout || dirty || dirtyChildren) {      
+    //   or the client area is wider than us
+    if (relayout || dirty || dirtyChildren || childRect.width < clientRect.width) {
       childRect.x = 0;
       childRect.y = yOffset;
       childRect.width = clientRect.width;
@@ -232,7 +234,6 @@ nsListBoxLayout::LayoutInternal(nsIBox* aBox, nsBoxLayoutState& 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.
-      box->GetBounds(childRect);
       PRInt32 newPos = yOffset+margin.top;
 
       // are we pushing down or pulling up any rows?