Thanks for the notes!

I've filed one issue for a keyboard shortcut for change tab: https://github.com/mapbox/tilemill/issues/1380 and there's already one for find functionality: https://github.com/mapbox/tilemill/issues/968 .

Lion-esque save-constantly behavior would be a bug at this point. Map rendering would need to be instant and isn't.

Tying these changes to 'a native UI' though, doesn't make a lot of sense: none of these changes are impossible, or even more difficult, because the code is in javascript rather than cocoa.