What is the purpose of xeyes?

xeyes is not for fun, at least not only. The purpose of this program is to let you follow the mouse pointer which is sometimes hard to see. It is very useful on multi-headed computers, where monitors are separated by some distance, and if someone (say teacher at school) wants to present something on the screen, the others on their monitors can easily follow the mouse with xeyes.

Currently xeyes is also useful to work out which Linux apps use Wayland or XWayland. Hovering mouse over an XWayland window moves eyes, while native Wayland windows can not communicate with with X11 server.

xeyes is not only fun it is a useful utility if you have a big screen and a small cursor. Second, it is an example program for the x toolkit intrinsics (Xt) library. XEyes implements an Xt Widget (Eyes.c) and has a nice, clean xt initialisation sequence (xeyes.c). It also initialises the "application icon" (XtNiconPixmap) and catches the window quit event from the window manager (WM_DELETE_WINDOW). A very useful example.