Oh yes, the Alt+Space button, which I still use for windows restores (Alt+Space+R) instead of Win+Down for some reason. And for the occasional rescue of windows that have entirely escaped by screens.
Ms have a long track record of supporting legacy interactions and interfaces - for instance, you could still use fileman and progman in win7, although by that stage it did involve installing them yourself. They shipped with every version up to xp. http://chorusofone.no-ip.org/computerstuff/win7progman.html
That's pretty much the only way to get offscreen windows back onto the desktop - "Alt+Space, M, Left arrow, Up arrow".
It's certainly added a fun little extra layer of puzzle to my life. I bet this is how Catherine felt about Atrus' door puzzle locks as she wandered Myst Island.
> A single click on the button brings up the system menu. I never bothered about that much, because this button isn't really meant to be single clicked
I disagree here. I feel single click is more useful than the the double click to close.
Edit: assuming you have a keyboard with an insert key, and that it's not in a ridiculous location, of course.