Be careful what you wish for. I use one application which does not check whether the computer goes from 2 external monitors to the built-in laptop monitor. When I reopen the app on the laptop without the external monitors, all of its windows are drawn completely off the screen. The only way I know how to fix this is to reattach the external monitors, move the windows to the built-in screen, then close the app again.
Shouldn't your window manager just handle this for you, by moving the windows to the builtin display when the external monitor is detached, and moving them back again when it's reattached? (Like my Mac has been doing for I don't know how long?)
I'm not sure what this comment is supposed to add to the discussion. It's the same as those comments that just say "This", except it does it with 40x the number of words, no?
