I know I've been for the most part silent for the past 4+ years. I've had my head down completing my PhD, and then this fall teaching my first semester of classes as a Computer Science professor.
I finally managed to get enough time over the holidays to make the changes to integrate the new version of libSDL 2.0 into Atari800MacX. The 2.0 version makes wholesale changes to many things, including rendering, sound, and keypresses, so it took me about 2 weeks of effort to make the changes. The good news is that moving to 2.0 should enable the emulator to with stand changes to Mac OSX in future versions, assuming that the library authors keep up with them.
It looks like it was coincidence that people have been busy developing their own fixes around the same time I got time to take a look, and I really appreciate the help, as I have had zero time to do anything the past 4 years.
The changes fix the sound and full screen issues, as well as printer emulation which wasn't working anymore either. Be aware though it is still Alpha quality software, as the amount of testing I have done is limited (although I'm sure all of you can help there ).
I'm just waiting for Al to give me new FTP credentials so I can post version 5.0 of AtariMacX to the web site.