A lot has happened since the last post.
srp/doctashay added full screen DrawSprockets, OpenGL and audio. He redid the event handling and finished keyboard decoding. He also fixed dozens of tiny bugs in threads and timers and main(), etc.
He used it for a port of Half-Life for MacOS 9. (Still a bit buggy and parts may need to be finished, but an amazing proof of concept).
I rolled his work in, and used it to successfully build a few games which previously had been crashy or didn't work.
Made InputSprocket, DrawSprocket and OpenGL optional again, which were made required for Half-Life. Fixed m68k support.
Added m68k OpenGL support via a super hacked Mesa, where I "fixed" its AGL to be mostly source compatible with Apple's real one for ppc macs. I tweaked it a bit, so it has SOME added OpenGL 1.2 features and functions. (I went back and did the same for SDL 1.2). It is very slow, but fully functional, as far as I can tell.
(The mesa work is available in a separate github repo).
I've since been able to build all the "add-ons" like SDL2_image, SDL2_mixer, etc, with (pretty much) full external libraries and supported formats.
Made countless tiny fixes and improvements in general, especially with the build process.
Created "dummy" InputSprockets and DrawSprockets which can be used for m68k or ppc systems that might not have them. May one day implement basic functionality. They return errors, or ignore most things.
Created "macos8addons" which are some functions which Apple included for ppc 8.5 and higher, but not for 8 or lower (even on ppc).
You can follow my progress via my github commits.