Bug 134954 Library can't be removed
Steps to reproduce: 1.New a report "a.rptdesign" 2.New a library which is not in the same fold with report, saying "../test/lib.rptlibrary" 3.Report includes the library 4.Remove the library Expected result: The library is removed Actual result: Open XMLSource, the included library structure is still there.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/LibraryCommand.java
*            the design element
	 * @return the map containing local values of virtual elements. The key is
	 *         the base id of virtual element and the value is property
	 *         name/value pair.
	 * @throws SemanticException
	 *             if error occurs during removing virtual elements.
	 */
	private Map unresolveElementDescendent( Module module, DesignElement child )
			throws SemanticException
	{
		ElementRefValue value = (ElementRefValue) child.getLocalProperty(
				module, DesignElement.EXTENDS_PROP );
		DesignElement parent = value.getElement( );
		assert parent != null;
		
		if ( child.getDefn( ).getSlotCount( ) == 0 )
		{
			
			parent.dropDerived( child );
			value.unresolved( value.getName( ) );
			return Collections.EMPTY_MAP;
		}
		Map overriddenValues = ElementStructureUtil
				.collectPropertyValues( child );
		
		LevelContentIterator contentIter = new LevelContentIterator( child, 1 );
		while ( contentIter.hasNext( ) )
		{
			DesignElement tmpElement = (DesignElement) contentIter.next( );
			ContentCommand command = new ContentCommand( module, child );