@neauoire so some_little_program needs to know the X window ID to send events to. Some ideas: you could just type it in; some_little_program could observe what window has focus at the moment it starts and use that one forever; one of the programs (I'm not sure which one) could make you click on the target window and listen for the event and use the target of the click for all future events.
@drj Oooh! Yes, okay, let say I wanted to make it so some_little_program waits for a click on a window(`click on any window`), do you know how I can do this?