If you set the screen res of the game to larger than your display's size, you can end up in a situation where you have to edit the settings.txt by hand to recover.
I suspect the retina iMac will cause this problem more often, because although the native res is 5000xsomething, the EU IV mac app isn't aware that it's running screen doubled, so setting the res to 2300xsomething will cause this issue.
I suspect the retina iMac will cause this problem more often, because although the native res is 5000xsomething, the EU IV mac app isn't aware that it's running screen doubled, so setting the res to 2300xsomething will cause this issue.