Ya, it's in XBMC settings (System > video, I believe). It's such a silly thing.. XBMC just has trouble restoring its screen with a bunch of programs. It seems like the "Use fullscreen window instead of fullscreen" works better with the majority of programs, maybe not spelunky though.
Didn't have a chance to test last night, was too busy trying to get my AC working.
Ok, I found that setting and tried both ways. Works ok for me - minimizes XBMC on launch and restores to full screen when i quit.
I love and hate XBMC, the menus and navigation I think are generally terrible, but there are so many slick addons and skins and customization options.. getting everything to work the way you want is a nightmare.
But a mod where you can freeze everything exceept yourself. Is that possible
Probably, but you would have to find another way to do it.. the term Frozen Region is misleading i guess because it suggests everything is just paused, but it is really deactivated. So...there is nothing to see (other than tiles/backgrounds), and nothing for the player to stand on.
http://spelunky.wikia.com/wiki/Frozen_region