private void OnClassToInterfaceChanged(ClassToInterfaceEvent domainEvent)
 {
     // item could already be added because it was a base class of this classifier
     // so do not add it again when this event appears
     var item = ByName(domainEvent.ClassName);
     if (item != null)
         return;
     // add the new interface to the list
     var @class = _classifiers.FindByName(domainEvent.ClassName);
     Add(new ClassifierItemViewModel(@class.Name));
 }
 private void OnClassToInterfaceChanged(ClassToInterfaceEvent domainEvent)
 {
     var item = ByName(domainEvent.ClassName);
     if (item != null)
         Remove(item);
 }