I find this fascinating. I also like to customize my desktop experience with my own code, but it's more assembling stuff with some additional code as glue.

A word of warning: a reliable lock tool for X11 is difficult. You should look at XSecureLock, which uses a multiprocess approach to avoid leaving the desktop unprotected in case of crash. It also implements a number of countermeasure to ensure the desktop stays locked and the locker stays in the front of the display. It's small too, so easy to audit (but written in C).

Thanks. I'll look into it and borrow whatever is useful there into bolt.