private void UserLoginCheck(object sender, System.Windows.RoutedEventArgs e)
        {
            ClientServerUtil csu = ClientServerUtil.getInstance();

            csu.serverPc = ServerInput.Text;
            var username = UsernameInput.Text;
            var password = PasswordInput.Text;

            try
            {
                csu.login(username, password, this);
                LoginPanel.IsOpen          = false;
                UsernameIfLoggedIn.Content = "Eingeloggt als \n" + UsernameInput.Text;
                initFactoryPulldown(csu);
            }
            catch (LoginException ex)
            {
                Console.WriteLine(ex.StackTrace);
                showPopUp(ex.Message);
            }
        }