When I (stupidly) try to save as X.3dm while a different document named X.3dm is open, I get the expected “X exists, replace?” message. If I choose replace, Rhino hangs (beach ball) and doesn’t respond to Apple events or the keyboard.
MacBook Pro, Retina, Mid 2012
OS X 10.8.5 (12F45)
5.0 Wenatchee 2014-02-03 (501)