The Python version of lesson 48 (ArcBall) was last changed in 2004 by Brian Leair and it does not work with Python 3.x. I have made all the necessary changes and cleanup for it to work with Python 3.2. I have also added rotate() and getTransform() functions to the Arcball class. These functions were present in the original C++ version of Arcball created by Terence J. Grant (http://tatewake.com/) The updated NeHe Lesson 48 (ArcBall) for Python is attached to this post.