Bug 129886 Delect a column contain the marge row which contain some item, Error message pop up
Details: Delect a column contain the marge row which contain some item, Error message pop up Setp: 1.New a library and add a 3*3 grid 2.Insert a label in cell(1,1) 3.Marge the cell of (1,1) and (1,2) 4.Delete column 1. Actual result: An error message pop up
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/editors/schematic/editparts/TableEditPart.java
*/
	protected GridLayer createGridLayer( )
	{
		GridLayer grid = new TableGridLayer( this );
		grid.setOpaque( false );
		return grid;
	}
	/**
	 * Creates a layered pane and the layers that should be printed.
	 * 
	 * @see org.eclipse.gef.print.PrintGraphicalViewerOperation
	 * @return a new LayeredPane containing the printable layers
	 */
	protected LayeredPane createPrintableLayers( )
	{
		FreeformLayeredPane layeredPane = new FreeformLayeredPane( );
		FreeformLayer layer = new FreeformLayer( );
		layer.setLayoutManager( new TableLayout( this ) );
		layeredPane.add( layer, PRIMARY_LAYER );
		layeredPane.add( new TableBorderLayer( this ), BORDER_LAYER );
		return layeredPane;
	}
	/**
	 * this layer may be a un-useful layer.
	 * 
	 * @return the layered pane containing all printable content
	 */
	protected LayeredPane getPrintableLayers( )
	{
		if ( printableLayers == null )