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
if ( !slotInfo.canContain( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_WRONG_TYPE );
		
		
		if ( element.isVirtualElement( ) || element.getExtendsName( ) != null )
			throw new ContentException(
					element,
					slotID,
					content,
					ContentException.DESIGN_EXCEPTION_STRUCTURE_CHANGE_FORBIDDEN );
		
		if ( element.isContentOf( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_RECURSIVE );
		
		if ( !slotInfo.isMultipleCardinality( )
				&& element.getSlot( slotID ).getCount( ) > 0 )
		{
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_SLOT_IS_FULL );
		}
		if ( slotID == Module.COMPONENT_SLOT )
		{
			if ( StringUtil.isBlank( content.getName( ) ) )
				throw new ContentException( element, slotID, content,
						ContentException.DESIGN_EXCEPTION_CONTENT_NAME_REQUIRED );
		}
		checkContainmentContext( slotID, content );