Configure problem [linux]

I can’t get the sdl ./configure script to recognise that I have X
installed and compile the X11 video code accordingly.
I can run under X11 using a libSDL which was compiled on another machine
without problems.
I can do “./configure --enable-video-aalib” and run fine in ascii mode
(Creatures 3 in ascii mode - wheeeee!), but it just doesn’t want to
compile in the X11 code.

I’m running frozen Debian (2.2) with a retrofitted XF86 4.01 (which is
probably asking for trouble). As far as I can tell, all the includes and
libraries are in the right place, and I’m not having any other problems
with X…

Anyone have any ideas?
How does ./configure decide if X is installed?

Ben Campbell
Programmer, Creature Labs
ben.campbell at