In Ubuntu, using dosbox and going fullscreen, sets display setting to "mirror" when I'm using an external monitor. Then, it never goes back to extended desktop.
It should go fullscreen only in the corresponding display, and respect the current desktop settings.
Bug report in ubuntu: https://bugs.launchpad.net/ubuntu/+source/dosbox/+bug/498513
Bug report in debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=539740