Bug 154828 Item from library contant user properties can't delete
Details: Item from library contant user properties can't delete Step: 1.New a library. 2.Add a label and add a user properites. 3.Public the library. 4.New a report design and use the library 5.Drop the label from library explorer into layout. 6.Try to delete it. Actual result: The label from library contant user properties can't be delete. Exception reuslt: The label can be delete.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/ContentCommand.java
throws ContentException
	{
		assert content != null;
		
		if ( !element.getDefn( ).isContainer( ) )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_NOT_CONTAINER );
		ContainerSlot slot = element.getSlot( slotID );
		if ( slot == null )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_SLOT_NOT_FOUND );
		if ( !content.isContentOf( element ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_CONTENT_NOT_FOUND );
		
		SlotDefn slotInfo = (SlotDefn) element.getDefn( ).getSlot( slotID );
		if ( !slotInfo.isMultipleCardinality( ) )
			return;
		
		
		if ( content.isVirtualElement( ) )
			throw new ContentException(
					element,
					slotID,
					content,
					ContentException.DESIGN_EXCEPTION_STRUCTURE_CHANGE_FORBIDDEN );
		if ( !canMovePosition( content, slotID, newPosn ) )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_MOVE_FORBIDDEN );
		int oldPosn = slot.findPosn( content );