SDL 1.x is used for display, rather than Mac OS X specific backend. If time permits, I'll port it to SDL 2, if only to reduce Basilisk's overall code foot-print.
Lots of features are apt to be disabled, as many 'dummy' backends were used.
Video-depths other than 1-bit or 32-bit are untested, and in some cases (4-bit, at least) are currently non-functional. This is due to a partial re-write of the SDL backend's blitting code, which was non-functional when low-bit-depths were used.
The SDL backend was also rewired, on OSX, to not attempt to align the display buffer on page-boundaries. So far, this doesn't seem to cause any notice-able problems, however, that's only using limited knowledge and testing (System 7.5.x does boot and display at 640x480, though!). The original display-buffer allocation code was failing to run, in some cases.
Preferences are, on Mac, currently hardcoded to be accessed at /tmp/BasiliskII/BasiliskII_Prefs. The folder, "/tmp/BasiliskII/", may be a symbolic link to elsewhere, though.
kanjitalk755
David Ludwig
Alexei Svitkine
Christian Bauer