     {
         gridLayout.clearVirtualLayoutCache();
         
+        const gridDimensions:GridDimensions = this.gridDimensions;
         if (gridDimensions)
         {
             if (clearTypicalSizes)

        
        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);
        

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