Interesting. Definitely a 3rd approach that threads the needle between what win32 and X Window chose. Thanks for the link.

[ EDIT: not quite sure how to think about this ... if I create NSThreads to act as worker threads that do not make cocoa calls, I still have to deal with new overhead in any cocoa call stacks. That's not ideal, but again, it's a "middle-way" approach, and like every other approach has its own pros and cons. ]