void timer_Elapsed(object sender, ElapsedEventArgs e) { this.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Normal, (Action)(() => { if (pgbLogoff.Value < 50) { pgbLogoff.Value += 1; } else { ThemeManager.ChangeAppTheme(Application.Current, "BaseDark"); timer.Stop(); LoginScreen loginScreen = new LoginScreen(); loginScreen.Show(); this.Close(); } })); }