private async void OnLogOn() { var client = new ChatClient(); await client.StartAsync(); try { var info = await client.LogOn(int.Parse(_userIdInput)); var current = Application.Current.MainWindow; var mainVM = new MainViewModel(client, info); var mainWindow = new MainWindow(); Application.Current.MainWindow = mainWindow; mainWindow.DataContext = mainVM; current.Close(); mainWindow.Show(); } catch (DuplicateIdException) { } }