mrchris, I feel your pain. I’m stuck with processing-2 on my chromebook linux container. I wrote quite a bit for processing-3.5.3 and then it broke and I get the similar GL mapping errors that you get. If there’s a fix, I’d like to use it too.
coincidentally, I was using an RC flight simulator with an arduino interface for the transmitter over USB, called crrcsim. It worked great. I got a new update on the chromebook and now it won’t load the scenery so it just sits there stuck and flickering. crrcsim is written in c++ but it uses OpenGL and my theory is Google keeps screwing with something that affects OpenGL. It works great and then they “improve” it for some reason and break the very things you use or want. That’s actually been my experience with computers since the intel 286 days, glory or victory is not to be for longer than the next update.
I might just pack my bags, correction, might just take the clothes on my back, buy a rubber life raft and some basic gear and take to the sea. At least then my fate is truly up to me. Oh never mind, I’ve seen Castaway.