This is really cool, Michel wrote this for his Apple II emulator, and I've been using it (as a slight troll) to replace the front-end for an Archimedes emulator. It's early days, but if _I_ can understand the API, it must be OK :)
If one in 1988 wanted to port a MacOS application to GS/OS, how difficult would it have been? What would have been the IIgs equivalent to, say, MPW?