Bug 146159 [Regression]Changing font operation doesn't work other than the first time
Description: The first time changing operation can work well. However, Change it again, it won't work. Steps: 1.Insert lable/text to layout or master page 2.Change the font from serif to cursive, it works well 3.Change the font again Result: The action doesn't work Additional infor: build number:200606080632
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/editors/schematic/editparts/ReportElementEditPart.java
/**
	 * adds model listener
	 */
	protected void addModelListener( )
	{
		if ( getModel( ) instanceof DesignElementHandle )
		{
			( (DesignElementHandle) getModel( ) ).addListener( this );
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.gef.EditPart#deactivate()
	 */
	public void deactivate( )
	{
		if ( !isActive( ) )
			return;
		removeGuideFeedBack( );
		removeModelLister( );
		super.deactivate( );
		HandleAdapterFactory.getInstance( ).remove( getModel( ) );
	}
	/**
	 * Removes the model listener.
	 */
	protected void removeModelLister( )
	{
		if ( getModel( ) instanceof DesignElementHandle )