I've implemented the Integer Line and Fractional Line drawing modes based on pseudocode in the REX3 documentation that SGI published. It's hardly noticeable, but the lines are now slightly thicker on buttonfly:
I also fixed an off-by-one error when handling the Length32 flag, which was causing cracks in certain geometry. Similarly, I fixed a whole host of other bugs and added alpha-blending support, leading to these two shots:
The Newton demo, in particular, used to look like this: