public MainWindowViewModel(IAppController appController, IPatientRepository patientRepository) { _appController = appController; _patientRepository = patientRepository; AddWorkspace = new RelayCommand(param => { var ws = _appController.GetWorkspace(); ws.CloseView += OnWorkspaceClose; _workspaces.Add(ws); }); _workspaces = new ObservableCollection<IWorkspace>(); Workspaces = CollectionViewSource.GetDefaultView(_workspaces); }