Bug 148747 Design become invalid when I extend a masterpage from Library
The attachment contains a report file and a library file. Reproduce: 1. Deploy the library("lib"), and open the report. 2. Drag Masterpage("page1") from "lib" to report. 3. Reopen the report, it become invalid.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/parser/ReportElementState.java
String extendsName = element.getExtendsName( );
		if ( StringUtil.isBlank( extendsName ) )
			return;
		DesignElement parent = module.resolveElement( extendsName, id, element
				.getPropertyDefn( IDesignElementModel.EXTENDS_PROP ) );
		if ( parent == null )
		{
			handler
					.getErrorHandler( )
					.semanticWarning(
							new InvalidParentException(
									element,
									extendsName,
									InvalidParentException.DESIGN_EXCEPTION_PARENT_NOT_FOUND ) );
			return;
		}
		try
		{
			assert parent != null;
			element.checkExtends( parent );
		}
		catch ( ExtendsException ex )
		{
			handler.getErrorHandler( ).semanticError( ex );
		}
		element.setExtendsElement( parent );
		element.refreshStructureFromParent( module );
		addTheVirualElementsToNamesapce( element );
	}
	/**