Bug 183918 get relative file path of linkage library
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/library/DesignLoadLibraryTest.java
designHandle.getStyles( ).drop( designStyleHandle );
		assertEquals( libStyleHandle, label.getStyle( ) );
		
		designHandle.getCommandStack( ).undo( );
		assertEquals( designStyleHandle, label.getStyle( ) );
		
		designHandle.getCommandStack( ).undo( );
		assertEquals( libStyleHandle, label.getStyle( ) );
		
		designHandle.getCommandStack( ).redo( );
		assertEquals( designStyleHandle, label.getStyle( ) );
		
		
		designStyleHandle.drop( );
		assertEquals( libStyleHandle, label.getStyle( ) );
		
		designStyleHandle = designHandle.getElementFactory( ).newStyle(
				"style3" ); 
		designHandle.getStyles( ).add( designStyleHandle );
		assertEquals( designStyleHandle, label.getStyle( ) );
		
		designStyleHandle.setName( "newStyle" ); 
		assertEquals( "newStyle", label.getStyle( ).getName( ) ); 
		
		designHandle.getCommandStack( ).undo( );
		assertEquals( "style3", label.getStyle( ).getName( ) ); 
		
		designHandle.getCommandStack( ).redo( );
		assertEquals( "newStyle", label.getStyle( ).getName( ) );