Example cycle shows how to use the cycle prompt. It is by no means comprehensive and should not be considered functional. Namely, it polls for state once and never updates itself. The example is intended to half-heartedly emulate an alt-tab window cycling dialog.
A proper usage of alt-tab would require listening for changes on the _NET_CLIENT_STACKING_LIST property and listening for changes on each individual window (like its name, icon and existence itself).