[Unison-hackers] MAC OS issue ... only with the GUI version

[Trevor Jim]

I've got a question in to the ocaml list about this.  I think we are
still missing some locks, but I need more information to figure out
where, as this is not documented in ocaml.

Given the constraints on how threaded ObjC programs can call into
ocaml, it may be that the threads that Ben (?) added to improve
responsiveness will end up being ineffective... too early to tell
yet.

-Trevor