Save/Restore Window Configuration

[mnp]

So I have a feature in mind which might belong in a fork of ewmctrl, but I could also envision it being an addition with a couple of keys. Here's a rough sketch.

I want to know if a screen got added or removed, and reposition my favorite windows to where they belong for each screen configuration. It's nice this can be done inside emacs instead of outside in the window manager, because I might also want to adjust things inside emacs when the change is detected. So the feature might look like this:

1. In the list view, user marks a few windows as either manged or not managed.
2. Record the titles and current geometries of those windows, along with the current (display-width, display-height) values into a little state file.
3. Register a timer to check every few seconds and see if the display has changed
4. On change, fire a reconfigure action:
   4a. Look up the new width/height in the file and rearrange each of the windows listed there, if found, to where they used to be,
   4b. Run a change detected hook for arbitrary code.

I have the change detection code working (3), and am now pondering a UI something like the above. Happy to share code, or maybe fork.

Any thoughts?