private void ApplicationStart(object sender, StartupEventArgs e) { EventManager.RegisterClassHandler(typeof(TextBox), TextBox.KeyDownEvent, new KeyEventHandler(TextBox_KeyDown)); EventManager.RegisterClassHandler(typeof(CheckBox), CheckBox.KeyDownEvent, new KeyEventHandler(CheckBox_KeyDown)); //Disable shutdown when the dialog closes Current.ShutdownMode = ShutdownMode.OnExplicitShutdown; var dialog = new LoginWindow(); if (dialog.ShowDialog() == true) { var mainWindow = new MainWindow(dialog.currentUser); //Re-enable normal shutdown mode. Current.ShutdownMode = ShutdownMode.OnMainWindowClose; Current.MainWindow = mainWindow; mainWindow.Show(); } else { MessageBox.Show("Отказан достъп.", "Грешка", MessageBoxButton.OK); Current.Shutdown(-1); } }