Bug 152300 Model api is wrong.
In the LibrarCommand class,the method reloadLibrary , code lije this: activityStack.commit( ); // clears the activity stack to avoid potential problems. activityStack.flush( ); LibraryReloadedEvent event = new LibraryReloadedEvent( module .getLibraryByLocation( url.toExternalForm( ) ) ); module.broadcast( event ); Please first fire model event,then fire the commandstack event.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/LibraryCommand.java
*/
	private Map unresolveElementDescendent( Module module, DesignElement child )
			throws SemanticException
	{
		ElementRefValue value = (ElementRefValue) child.getLocalProperty(
				module, DesignElement.EXTENDS_PROP );
		DesignElement parent = value.getElement( );
		assert parent != null;
		
		if ( child.getDefn( ).getSlotCount( ) == 0 )
		{
			
			parent.dropDerived( child );
			value.unresolved( value.getName( ) );
			return Collections.EMPTY_MAP;
		}
		Map overriddenValues = ElementStructureUtil
				.collectPropertyValues( child );
		
		ActivityStack activityStack = getActivityStack( );
		activityStack.startSilentTrans( );
		LevelContentIterator contentIter = new LevelContentIterator( child, 1 );
		while ( contentIter.hasNext( ) )
		{
			DesignElement tmpElement = (DesignElement) contentIter.next( );
			ContentCommand command = new ContentCommand( module, child );
			command.remove( tmpElement, tmpElement.getContainerSlot( ), false,
					true );
		}
		activityStack.commit( );