[otrs] Notify style can‘t changed ，may be a bug

Hi all Version 4.0.5, when i modify "Frontend::NotifyModule###900-Generic" , set "Priority" value eq "Info" , notify message style can't changed . (Layout.pm: ​$BoxClass :{Notice,Error,Success,Info}) So i edit NotificationGeneric.pm ,found ​only "Error" and "Notice" priority can be switched to . code: { .......line 39 ​ if ( $Param{Config}->{Priority} & } ... } is a bug? or Priority only set "Error" or "Notice"?