diff --git a/mozilla/lib/mac/UserInterface/Tables/CStandardFlexTable.cp b/mozilla/lib/mac/UserInterface/Tables/CStandardFlexTable.cp
index 55357e73cf1..5eaad503c6d 100755
--- a/mozilla/lib/mac/UserInterface/Tables/CStandardFlexTable.cp
+++ b/mozilla/lib/mac/UserInterface/Tables/CStandardFlexTable.cp
@@ -1909,7 +1909,7 @@ void CStandardFlexTable::InsideDropArea(DragReference inDragRef)
 			// the user's holding the mouse down on this row, & we just noticed
 			STableCell cell(mDropRow, GetHiliteColumn());
 			Boolean expanded;
-			if (CellHasDropFlag(cell, expanded) && !expanded)
+			if (RowIsContainer(mDropRow, &expanded) && !expanded)
 			{
 				SetCellExpansion(cell, true);
 				// The revealed rows should be there now, just draw them.
@@ -2623,6 +2623,21 @@ void CStandardFlexTable::ClickCountToOpen ( Uint16 inNewCount )
 } // CStandardFlexTable::TableSupportsNaturalOrderSort
 
 
+//----------------------------------------------------------------------------------------
+Boolean
+CStandardFlexTable :: RowIsContainer( const TableIndexT & inRow, Boolean* outIsExpanded ) const
+// Default implementation, just returns false.
+//----------------------------------------------------------------------------------------
+{
+	Assert_(outIsExpanded != NULL);
+	if ( outIsExpanded )
+		*outIsExpanded = false;
+		
+	return false;
+
+} // RowIsContainer
+
+
 #pragma mark -
 #if defined(QAP_BUILD)
 
diff --git a/mozilla/lib/mac/UserInterface/Tables/CStandardFlexTable.h b/mozilla/lib/mac/UserInterface/Tables/CStandardFlexTable.h
index 556d466ee06..c1d91234856 100755
--- a/mozilla/lib/mac/UserInterface/Tables/CStandardFlexTable.h
+++ b/mozilla/lib/mac/UserInterface/Tables/CStandardFlexTable.h
@@ -369,6 +369,8 @@ protected:
 							TableIndexT		inDropRow);
 	virtual Boolean		RowIsContainer(
 							const TableIndexT & /* inRow */ ) const { return false; }
+	virtual Boolean		RowIsContainer(
+							const TableIndexT & /* inRow */, Boolean* /*outIsExpanded*/ ) const ;
 	void				ComputeItemDropAreas(
 							const Rect& inLocalCellRect,
 							Rect& outTop,