 
         if (tween)
             return;
+		
+		if (!visibleColumns || !visibleColumns.length)
+			return;
 
         // mouse-out should remove the "proposed" numeric sort icon
         if (!sortExpertMode)

     */
    override protected function mouseDownHandler(event:MouseEvent):void
    {
        if (!tween)
        {
            super.mouseDownHandler(event);
            updateSelectedCells();

     */
    override protected function mouseDoubleClickHandler(event:MouseEvent):void
    {
        if (!tween && visibleColumns && visibleColumns.length > 0)
            super.mouseDoubleClickHandler(event);
    }
    
