I want to thank you for this page! It really helped me understand how X11 worked when my job at the time required some rather esoteric (to me) X11 knowledge. I had to write a very specific purpose window manager (in JavaScript, which really made it interesting) that had to work around some odd client behavior, and I also had to submit a patch to X.org to fix a bug in Xephyr. Without your guide I would have spent far longer digging in the docs to figure things out.