I know remarkably little about Python and GTK, but from the two URLs shown in the source code below I was able to piece together a working, “Well, world” screensaver. Well, calling it a screensaver is a stretch, because what it will really do is burn the characters “Hello, world” into your monitor; but at least I cracked the code on how to get this started.
To try this on your own Linux system running
xscreensaver, first save the following source code somewhere. I’ll assume that you’ve saved it to /home/al/hello.py: