What's the deal with fullscreen and DGA?
The difference between in a window and fullscreen is actually quite minor. When you're in fullscreen mode what you've done is zoomed in your desktop and moved the zoomed portion to cover just the window. (Just the same hitting Ctrl-Alt-plus and Ctrl-Alt-minus) The game still runs in a window in either case. So, the behavior shouldn't be any different.
DGA is turned off in the current configuration. I've just started adding those features back in. The latest code in the trunk has some support for DGA but is broken, the code in my tdfx-1-1 branch should be working.