         
         // If columnIndex refers to a visible header renderer, return it
         
+        const rendererLayer:Group = rendererLayer;
         const visibleColumnIndices:Vector.<int> = grid.getVisibleColumnIndices();
         const eltIndex:int = visibleColumnIndices.indexOf(columnIndex);
         if (eltIndex != -1)
         {
-            const columnHeaderGroupNumElements:int = columnHeaderGroup.numElements;
-            for (var index:int = 0; index < columnHeaderGroupNumElements; index++)
-            {
-                var elt:IGridItemRenderer = columnHeaderGroup.getElementAt(index) as IGridItemRenderer;
+            const rendererLayerNumElements:int = rendererLayer.numElements;
+            for (var index:int = 0; index < rendererLayerNumElements; index++)
+            {
+                var elt:IGridItemRenderer = rendererLayer.getElementAt(index) as IGridItemRenderer;
                 if (elt && elt.visible && elt.column && (elt.column.columnIndex == columnIndex))
                     return elt;
             }

    //  Internal variables
    //
    //--------------------------------------------------------------------------
    
    /**
     *  @private
     *  Cached header renderer heights maintained by the measure() method.
     */
    private const rendererHeights:Array = new Array();
    
    /**
     *  @private
     *  Bounds of all currently visible header renderers.
     */
    private const visibleRenderersBounds:Rectangle = new Rectangle();
    
    /**
     *  @private


        const visibleColumnIndices:Vector.<int> = grid.getVisibleColumnIndices();
        const oldRenderers:Dictionary = new Dictionary();
        const rendererLayer:Group = this.rendererLayer;
        const overlayLayer:Group = this.overlayLayer;
        const columnSeparatorFactory:IFactory = columnHeaderGroup.columnSeparator;
        
        var renderer:IGridItemRenderer;
        var separator:IVisualElement;
        var column:GridColumn;
        
        // Add all of the renderers whose column is still visible to oldRenderers and free the rest
        
        for each (renderer in visibleHeaderRenderers)
        {
            column = renderer.column;
            if (column && (visibleColumnIndices.indexOf(column.columnIndex) != -1))
            {
