     public function GridLayout()
     {
         super();
+        gridDimensions = new GridDimensions();
     }
 
     //--------------------------------------------------------------------------

    
    private function layoutEditorIndicator(layer:GridLayer):void
    {
        const rowIndex:int = grid.dataGrid.editorRowIndex;
        const columnIndex:int = grid.dataGrid.editorColumnIndex;
        var indicatorFactory:IFactory = grid.dataGrid.editorIndicator;
        
        // If the indicatorFactory has changed for the specified non-null indicator, 
        // then free the old indicator.

        
        // To avoid flashing, force all of the layers to render now
        
        if (backgroundLayer) backgroundLayer.validateNow();
        if (selectionLayer) selectionLayer.validateNow();
        if (overlayLayer) overlayLayer.validateNow();
        
        // The old visible row,column indices are no longer needed
        
