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
NameException.DESIGN_EXCEPTION_DUPLICATE ) );
				return;
			}
			DesignElement parent = content.getExtendsElement( );
			if ( id == Module.ELEMENT_NAME_SPACE && parent != null )
			{
				if ( parent.getContainerSlot( ) != Module.COMPONENT_SLOT )
				
				
				{
					handler
							.getErrorHandler( )
							.semanticError(
									new ExtendsForbiddenException(
											content,
											content.getElementName( ),
											ExtendsForbiddenException.DESIGN_EXCEPTION_PARENT_NOT_IN_COMPONENT ) );
					return;
				}
			}
			ns.insert( content );
		}
	}
	/**
	 * Add the virtual elements name into the module namespace.
	 * 
	 * @param element
	 *            the element contains virtual elements inside.
	 */
	private void addTheVirualElementsToNamesapce( DesignElement element )