The word at the bottom of the window is "Apply," not "done." Yes I click it every time.
I am using Calendar 6.0 (1645) in OS X 10.8.2 and whatever version of Calendar that comes with iOS 6.1.2 (10B146) and both of them use
Done. Are you certain you are using Calendar? (Apple renamed iCal to Calendar in OS X 10.8 for name compatibility with the iOS app.)
Well, it's certainly possible that the number field problem I described has been fixed in later versions of iCal than the one I used
It is not
fixed on any version of Calendar I am running on my Mac, iPhone, or iPad. They all do the same thing which can be annoying.