     {
         const eventStageXY:Point = new Point(event.stageX, event.stageY);
         const eventGridXY:Point = globalToLocal(eventStageXY);
-        const gridDimensions:GridDimensions = GridLayout(layout).gridDimensions;
+        const gridDimensions:GridDimensions = this.gridDimensions;
         const eventRowIndex:int = gridDimensions.getRowIndexAt(eventGridXY.x, eventGridXY.y);
         const eventColumnIndex:int = gridDimensions.getColumnIndexAt(eventGridXY.x, eventGridXY.y);
         

        
        const eventStageXY:Point = new Point(event.stageX, event.stageY);
        const eventGridXY:Point = globalToLocal(eventStageXY);
        const gridDimensions:GridDimensions = GridLayout(layout).gridDimensions;
        const eventRowIndex:int = gridDimensions.getRowIndexAt(eventGridXY.x, eventGridXY.y);
        const eventColumnIndex:int = gridDimensions.getColumnIndexAt(eventGridXY.x, eventGridXY.y);
        

    //
    //-------------------------------------------------------------------------- 
    
    /**
     *  @private
     */
    private function get gridDimensions():GridDimensions
    {
        return gridLayout.gridDimensions;
    }
    
    /** 
     *  @private
     *  Update the scroll position so that the virtual Grid element at the specified
