void PluginInstance::ObjectSelectionChangedEventHandler(ObjectEventArgs^ args)
{
   ModelObject ^obj = args->Object;
   Fragment3D^ fr3d = nullptr;

   if (obj->GroupType == ObjectType::Topol)
   {
      TopolReference^ topol = (TopolReference^)obj;

      for each (ParentObject ^p in topol->Parents)
      {
         fr3d = (Fragment3D^)p->Object;
         if (fr3d != nullptr)
            break;
      }
   }

   args->Document->Diagnostics->Add(
      gcnew DiagnosticsMessage(DiagnosticsMessageType::Information, 
         String::Format("select [id:{0}, type:{1}, parent:{2}]", 
            obj->ObjectId, obj->GroupType, fr3d ? fr3d->PathName : "NULL"), obj));
}