Rx ObserveOn SubscribeOn

In WPF Window update UI code look like the follwoing:

    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            Observable.Interval(TimeSpan.FromSeconds(1)).ObserveOn(Dispatcher).Subscribe((i) => this.Title = i.ToString());
        }
    }
or

 Observable.Interval(TimeSpan.FromSeconds(1)).ObserveOn(this).Subscribe((i) => this.Title = i.ToString());

ObserveOn = Notify Observer on a Dispatcher
SubscribeOn = Subscribe/unsubscribe Observers on a scheduler, where background/task pool will run.