double click mouse move in RX and WPF

gistfile1.cs

var target = new Border{ Background = Brushes.SteelBlue, Width = 200, Height = 200 };
var win = new Window{ Content = target };

var mouseDown = Observable.FromEventPattern<MouseEventArgs>(target, "MouseLeftButtonDown");
var mouseMove = Observable.FromEventPattern<MouseEventArgs>(target, "MouseMove");
var mouseUp = Observable.FromEventPattern<MouseEventArgs>(target, "MouseLeftButtonUp");

// dragEvents is IObservable<IObservable<EventPattern<MouseMoveEvent>>>
// The first dimmension represents the sequence of discrete drag "sessions"
// The second dimmension represents the sequence of moves within that drag
var dragEvents = mouseDown // for every mouse down
	.SelectMany(e => mouseDown
		.Take(1) // take the next mouse down
		// but timeout after 400ms.
		.Timeout(TimeSpan.FromMilliseconds(400), Observable.Empty<EventPattern<MouseEventArgs>>()))
	// then, for every double-click, take all the mouse moves
	// until you hit a mouse up event.
	.Select(e2 => mouseMove.TakeUntil(mouseUp));
	
// simulate user code
dragEvents
	.SelectMany(x => Observable.Defer(() => 
	{
		Console.WriteLine("start");
		return x.Do(y => Console.WriteLine("move")).Finally(() => Console.WriteLine("stop"));
	}))
	.Subscribe();

win.ShowDialog();