X container window

I'm working on a little program that will embed an X window into a Tk window, for the purpose of being able to run on-open and on-close scripts, essentially so I can save a list of open tabs in my file manager (pcmanfm) and restore them when I subsequently open the file manager. Embedding (reparenting) into a Tk window was the only way I could find to customize the event for closing a window. So far, I think I'll only have to rely on what I suspect is a fairly ubiquitous external (that is, non-tcl/tk) utility, xdotool. Quick poll: who does/doesn't have xdotool?

I did search for a way to do this, but I didn't find anything useful, so decided to try coding something myself. Anybody know of something?