Bug 315745 Two message pop up when switch from XML source to layout.[01]
UI/org.eclipse.birt.report.designer.ui.lib/src/org/eclipse/birt/report/designer/ui/editors/LibraryLayoutEditorFormPage.java
updateStackActions( );
			getEditor( ).editorDirtyStateChanged( );
			staleType = IPageStaleType.MODEL_CHANGED;
		}
	};
	protected void configureGraphicalViewer( )
	{
		super.configureGraphicalViewer( );
		WrapperCommandStack stack = (WrapperCommandStack) getCommandStack( );
		if ( stack != null )
		{
			stack.addCommandStackListener( getCommandStackListener( ) );
		}
	}
	/**
	 * returns command stack listener.
	 */
	public ActivityStackListener getCommandStackListener( )
	{
		return commandStackListener;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.ui.forms.editor.IFormPage#initialize(org.eclipse.ui.forms
	 * .editor.FormEditor)
	 */
	public void initialize( FormEditor editor )
	{