Async login example

 public partial class MainWindow : Window
    {
        public MainWindow()
        {
            WindowStartupLocation = WindowStartupLocation.CenterScreen;

            InitializeComponent();
        }

        private void LoginButton_Click(object sender, RoutedEventArgs e)
        {
            LoginButton.IsEnabled = false;
            var task = Task.Run(() => {

                Thread.Sleep(2000);

                return "Login Successful!";
            });

            task.ContinueWith((t) => {
                if (t.IsFaulted)
                {
                    Dispatcher.Invoke(() =>
                    {
                        LoginButton.Content = "Login failed!";
                        LoginButton.IsEnabled = true;
                    });
                }
                else
                {
                    Dispatcher.Invoke(() =>
                    {
                        LoginButton.Content = t.Result;
                        LoginButton.IsEnabled = true;
                    });
                }
            });
        }
    }