I stumbled on this glitch, though:

(The right border of the selection shifts)
I noticed a couple occasions where the UI doesn't behave like OS X, but it's just small graphical details that don't affect usability whatsoever. In doubt, I'll still list:
-if you tab to 'Ok' and hold space, the button's shade of blue twitches a couple times before settling down. 'Cancel' has the same behaviour.
-in OS X, clicking 'Ok' and moving out while holding the mouse button has the button display in "white" (rather than blue) to indicate it's won't be activated if you release. This works with "Cancel" but not "Ok" in the UI.
@Zantalos: I think Renegade_Turner means he's using a keypunch and machine language. Hence "gramps".