public ClientMainWindow() { InitializeComponent(); var loginWindow = new ClientLoginWindow(this); if (loginWindow.ShowDialog() == true) { logged = true; } else { this.Close(); return; } usersTimer = new DispatcherTimer(); usersTimer.Tick += new EventHandler(usersTimer_Tick); usersTimer.Interval = new TimeSpan(0, 0, 1); usersTimer.Start(); }