+Any program that can be made to render on an X window created by another
+process can be used as a screen saver. Just get the window ID out of
+$XSCREENSAVER_WINDOW, draw on that, and you're done.
+
+In theory, you can write a screen saver in any language you like. In
+practice, however, languages other than C or C++ tend not to allow you to
+draw to windows that they did not create themselves. Unfortunately, this
+means that if you want to write a screen saver, you must write it in C.
+
+Given that you're going to be writing in C, you might as well take
+advantage of the various utility functions that I have written to make
+that easier. Writing a new screen saver in C using the frameworks
+included with xscreensaver simplifies things enormously.