Bug 142432 MasterPage from library can't be restored to modify
Details: MasterPage from library can't be restored to modify Step: 1.New a library named lib1, and insert a masterpage named lib-mp. 2.Publish the library into resource folder. 3.New a report design and use lib1. 4.Drop the lib-mp from library explorer into outline of report design. 5.Double click lib-mp, and switch to Property editro tab. 6.Click restore. Actual result: Pop up an error message and said that the master page cannot specify size the page type is not custom.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/SimpleGroupElementHandle.java
throw e;
		}
		stack.commit( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.GroupElementHandle#isExtendedElements()
	 */
	public boolean isExtendedElements( )
	{
		if ( elements.isEmpty( ) )
			return false;
		for ( Iterator iter = elements.iterator( ); iter.hasNext( ); )
		{
			Object next = iter.next( );
			if ( !( next instanceof DesignElementHandle ) )
				return false;
			if ( ( (DesignElementHandle) next ).getExtends( ) == null )
				return false;
		}
		
		return true;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.GroupElementHandle#isPropertyReadOnly(java.lang.String)
	 */
	protected boolean isPropertyReadOnly( String propName )