Stylus support on Surface book?

I just ran an Urho app on Surface Book, and was pleasantly surprised that the touch worked flawlessly.

The stylus, however, didn’t seem to register at all. I had hoped that the stylus would just be registered as another touch, but that doesn’t seem to be the case. Is it a driver thing? Possibly an SDL thing?

Just found this helpful link: backworlds.com/under-pressure/