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
.getStringValue( ) );
		
		LibraryHandle library = designHandle.getLibrary( "Lib2" ); 
		designHandle.dropLibrary( library );
		assertEquals( ColorPropertyType.BLACK, label.getPrivateStyle( )
				.getColor( ).getStringValue( ) );
		
		library = designHandle.getLibrary( "Lib1" ); 
		designHandle.dropLibrary( library );
		
		assertEquals( ColorPropertyType.BLACK, label.getPrivateStyle( )
				.getColor( ).getStringValue( ) );
		
		designHandle.getCommandStack( ).undo( );
		assertEquals( ColorPropertyType.BLACK, label.getPrivateStyle( )
				.getColor( ).getStringValue( ) );
		
		designHandle.getCommandStack( ).undo( );
		assertEquals( ColorPropertyType.GREEN, label.getPrivateStyle( )
				.getColor( ).getStringValue( ) );
	}
	/**
	 * Test dropping a library.
	 * <p>
	 * 1) If library has a descendents in the current module, it can not be
	 * dropped.
	 * <p>
	 * 2) When user force to drop the library with descendents, all the
	 * derivatives in the current module will be localized.
	 * <p>