private void buttonLogin_Click(object sender, RoutedEventArgs e)
{
//Benutzername und Passwort überprüfen
this.Hide();
MainWindow mw = new MainWindow();
mw.ShowDialog();
this.Show();
}
private void Label_MouseDown_2(object sender, MouseButtonEventArgs e)
{
MainWindow _mw = new MainWindow();
_mw.InitializeComponent();
this.Close();
_mw.ShowDialog();
}