Camera Example project - how to get the camera angle?

Greetings!
I'm rather new to OpenGL but I enjoy the workflow with OpenTK a lot.

Amongst other things, I started writing a simple engine, based on the "Camera" example project: http://www.opentk.com/node/1292
Work is going well (http://twitpic.com/9q8lmd), but I've been fighting with one single problem for weeks now and I'm getting desperate.

How can I read out the camera direction angles - the way the camera is facing? It has to be in camera.cs or frame.cs.

I'm sorry that this question is very specific and a bit out of place here, but I'm completely at a loss with this.
Any help is greatly appreciated!

Thank you very much,
nomo_cc