Earlier quoted context omitted.
I promise you people have gotten this right. I have a 198? Mac Plus on my desk that I can boot up and do this on and it will work properly. I’m having trouble even imagining the insane event-processing architecture that results in keystrokes being processed out of order. Edit: Alright, alright, forget the old computer. My new ones get it right too. All of which is a red herring, because the point is this behavior is…
That Mac cannot multithread the UI interactions. It doesn't have to be a keystroke processing issue. It can be "hey window parent, I've got your result in my properties, pick it up" which doesn't get processed before the next event changes the related property. It's almost a classic TOCTOU issue.
https://en.m.wikipedia.org/wiki/Time-of-check_to_time-of-use