Actually, this kind of reminds me of how many controls still behave differently between Carbon and Cocoa--just as one example that I have handy, try holding the mouse button down and scrubbing over the tabs in a tab control. In Carbon it behaves like a button (only the tab you originally clicked will receive clicks) but in Cocoa it lets you scrub between all the tabs with the button held down. (rdar://2778946 ... filed in September 2001, still unfixed!) I don't have the HIG in front of me so I am not certain which way is more "correct," but I suspect the HIG doesn't leave the question unanswered.