if (getOwner( ).getParent( ) == null) { return ; }
	public AbstractPageFlowLayout( final GraphicalEditPart owner )	{		super( );		assert owner != null;		this.owner = owner;		final ControlListener listener = new ControlListener( )		{			public void controlMoved( ControlEvent e )			{			}			public void controlResized( ControlEvent e )			{				setComsiteBounds( new Rectangle( ( getOwner( ).getViewer( )						.getControl( ).getBounds( ) ) ) );				layouRootLayer( );			}		};		owner.getViewer( ).getControl( ).addControlListener( listener );		owner.addEditPartListener( new EditPartListener( )		{			public void childAdded( EditPart child, int index )			{				//Do nothing			}			public void partActivated( EditPart editpart )			{				//Do nothing			}			public void partDeactivated( EditPart editpart )			{				owner.getViewer( ).getControl( ).removeControlListener(						listener );			}			public void removingChild( EditPart child, int index )			{				// Do nothing			}			public void selectedStateChanged( EditPart editpart )			{				//Do nothing			}		} );		getZoomManager( ).addZoomListener( new ZoomListener( )		{			public void zoomChanged( double zoom )			{				setComsiteBounds( new Rectangle( ( getOwner( ).getViewer( )						.getControl( ).getBounds( ) ) ) );				layouRootLayer( );			}		} );	}