private bool CanExecuteShooterCollectionParticipation(UiParticipation obj)
 {
   return obj != null;
 }
 private void ExecuteCreateShooterCollectionParticipation(UiParticipation obj)
 {
   _windowService.ShowTextBoxInputDialog(string.Format("'{0}' Gruppe erstellen", obj.ParticipationName), "Gruppenname eingeben");
   LoadData();
 }