VGDD:External Widgets API
The External Widgets API are a set of specifications and interfaces to let you write the Dot.Net counterpart of an existing Graphics Library Widget (whose code you already have, written in C language).
This enables you to manipulate the graphical object in the designer and simulate it with the Player.
It's not an easy thing to do, but my commitment is in letting people to have the maximum flexibility when using VGDD.
That said, I'm sorry, the documentation has still to be written. :-)
If you are interested, use the forum to post a request.