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
assertEquals( designHandle.findElement( "label2" ), iter.next( ) ); 
		assertFalse( iter.hasNext( ) );
		
		designHandle.getCommandStack( ).undo( );
		
		iter = libLabel1.derivedIterator( );
		assertEquals( designHandle.findElement( "label2" ), iter.next( ) ); 
		assertEquals( designLabel3, iter.next( ) );
		assertFalse( iter.hasNext( ) );
		
		designHandle.getCommandStack( ).redo( );
		
		iter = libLabel1.derivedIterator( );
		assertEquals( designHandle.findElement( "label2" ), iter.next( ) ); 
		assertFalse( iter.hasNext( ) );
		
		TableHandle libTable1 = (TableHandle) libHandle
				.findElement( "libTable1" ); 
		TableHandle childTable = (TableHandle) designHandle.getElementFactory( )
				.newElementFrom( libTable1, "childTable" ); 
		assertEquals( "Employee Table", childTable.getCaption( ) ); 
		LabelHandle innerLabel = (LabelHandle) ( (CellHandle) ( (RowHandle) childTable
				.getDetail( ).get( 0 ) ).getCells( ).get( 0 ) ).getContent( )
				.get( 0 );
		assertEquals( "Cell 1-1", innerLabel.getText( ) ); 
	}
	/**
	 * Tests one design table extending one library table.
	 * 
	 * @throws Exception