[racket] instantiating multiple sandboxes with gui's

> I think you would need to abort the program and start it over to really do
> that properly.

Although I'm not yet convinced it can't be done properly, you have an
order of magnitude or two more experience in this area than I do, so I
appreciate that caution -- thanks!

> Avoiding the focus shift at the OS level seems easier (altho I don't know if
> what the right Mac OS X calls to do it are).

Well, it's the focus shift, and also the oddness of having that pop up
at all when coding non-GUI things (in my case that 99% of the time).

Also I also want it to work for other folks on Windows and GUI Linux,
and on non-GUI Emacs/Linux (e.g. a VPS or EC2 instance). So I'm
worried about the resulting test matrix. Although "Emacs is the one
true OS" is funny, there's a grain of truth in this case, that is
would be beneficial to avoid platform-specific stuff if possible. I
don't want to end up being that I just take pull requests from each
person who finds it wonky for their OS/version...

However I really appreciate the idea, and maybe that will turn out to
be the best way after all.