Bug 153038 NPE when delete master page content in old report design.
UI/org.eclipse.birt.report.designer.ui.editors.schematic/src/org/eclipse/birt/report/designer/internal/ui/editors/layout/ReportEditorWithPalette.java
if ( type == IPropertySheetPage.class )
		{
			ReportPropertySheetPage sheetPage = new ReportPropertySheetPage( );
			return sheetPage;
		}
		if ( type == DataViewPage.class )
		{
			DataViewTreeViewerPage page = new DataViewTreeViewerPage( getModel( ) );
			return page;
		}
		return super.getAdapter( type );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.designer.internal.ui.editors.parts.GraphicalEditorWithFlyoutPalette#dispose()
	 */
	public void dispose( )
	{
		if ( getCommandStack( ) != null )
		{
			getCommandStack( ).flush( );		
		}
		unhookModelEventManager( getModel( ) );
		super.dispose( );
		
		manager = null;
	}
}