WPF window update

/// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

        delegate void MDFunc(int i);

        //after clicking the Go button a set of calls to Func are queued
        private void Go(object sender, RoutedEventArgs e)
        {
            for (int i = 0; i < 10; i++)
                this.Dispatcher.BeginInvoke(DispatcherPriority.Normal, new MDFunc(Func), i);

        }

        //each time Func is called (from the dispatcher queue) it should update the button content so the user sees
        //the task progress
        void Func(int i)
        {
            Stopwatch S = new Stopwatch();
            S.Start();
            while (S.ElapsedMilliseconds < 500)
            { }

            button1.Content = i.ToString();
            button1.InvalidateVisual();
        }
    }