      */
     override public function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
     {
+        // TBD (hmuller): Short-circuit if there aren't any rows or columns.
+        
         if (!grid)
             return;
         

 	private function layoutColumns(scrollX:Number, scrollY:Number, width:Number):void
	{
        const gridDimensions:GridDimensions = gridDimensions;
        
        // If width isn't specified (see measure()), then only update requestedColumnCount columns
        
        const requestedColumnCount:int = grid.requestedColumnCount;
        var columnCount:int = gridDimensions.columnCount;
        if (isNaN(width) && (requestedColumnCount != -1))
            columnCount = Math.min(columnCount, requestedColumnCount);
        

    private function getGridColumn(columnIndex:int):GridColumn
    {
        const columns:IList = grid.columns;
        if ((columns == null) || (columnIndex >= columns.length) || (columnIndex < 0))
            return null;
        
        return columns.getItemAt(columnIndex) as GridColumn;
