private void saveBtnClicked(object sender, RoutedEventArgs e)
 {
     if (!ValidateFields())
     {
         return;
     }
     Model.Reservation tempReservation = staffMenu.ObservableReservations[reservationList.SelectedIndex];
     reservationList.SelectedIndex = -1;
     MyController.manageReservation.SaveReservation(tempReservation, tempReservation.ReservationId);
     staffMenu.updateReservationList();
     reservationList.Items.Refresh();
 }