I've programmed a lot in both UNIX and Windows environments, and I found that when I was working on UNIX machines I really missed having the "windiff" tool.
So, I've written a first pass at an X11 version of windiff, called xwindiff (obviously enough).
Note that my aim was to produce a quick and dirty clone of windiff; if you're looking for a graphical diffing tool with oodles of features and a rather prettier UI, you might like to try the splendid xxdiff
To build xwindiff, you'll need a UNIX system with X11 and Xt installed. The code is fairly portable; it's been built and run on:
-I/usr/contrib/X11R6/include and -L/usr/contrib/X11R6/lib to the
Makefile by hand)The part of the code that does the real work is taken from GNU diffutils2.7. As such, the GNU General Public License applies to the entirety of xwindiff.