public MainViewModel()
 {
     _biograf             = Biograf.Instance;
     _selectedFilm        = null;
     _forestillingsListe  = _biograf.AlleForestillinger;
     selectedForestilling = _forestillingsListe[0];
     _salViewModel        = new SalViewModel(selectedForestilling.Sal, selectedForestilling.AlleBookinger);
 }
 public ForestillingViewModel()
 {
     _forestilling = MainViewModel.selectedForestilling;
     _salViewModel = new SalViewModel(_forestilling.Sal, _forestilling.AlleBookinger);
     _instance     = this;
 }