MacOS 10.13+ is now required.
MAME 0.252 will feature improved Apple IIgs ADB emulation. This is an early release for anyone who wants to play around with it.
Previously, mouse and keyboard activity were written directly to the I/O registers. Now they pass through the ADB uC. This means sticky keys, mouse cursor, etc works on ROM3 and anything that reads ADB or ADB uC memory (Twilight II, Wolfenstein, ROM 1 sticky keys, etc) should be more accurate.