Hey @ccstone / Chris,
I kind of got sidetracked into trying to make Typora work the way I would like it to, but that’s not necessarily the direct path to my OP problem.
Were you ever able to get @CJK’s function to work?
I’m realizing that one of the purposes I had for the original question (but not all) was to be able to tell one desktop from another, to tell when a desktop had been moved, etc. and I think I can do that using some one specific app that is well behaved that way. Maybe TextEdit, maybe something else. The idea here is to emulate what CurrentKey does invisibly by having some app that has one window on each and every desktop and using that to force window changes.
Maybe I build a small app, maybe I dedicate some app that I don’t really use for anything else, so that leaves out TextEdit. Still sorting this one out.
About Mojave vs Catalina
I’m getting set to give up Mojave for Catalina. I don’t use my 32-bit apps much anymore and there are free or affordable alternatives to the ones I do. Mostly the threshold for me is that sharing Notes between my iPhone and my Mac, on Mojave I can share only individual files with another person while on the iPhone I can share whole folders with someone else, and then they disappear from the Mac because Mojave doesn’t grok shared folders. Moving to Catalina should fix this as well as give me updates to some other software that no longer supports Mojave.
I spent a day generating a list of all the 32-bit apps I had (there were 145 of them) and going through to see what I would miss if I deleted them (mostly Office 11 and a.bunch of Adobe stuff that I don’t use or the licence has expired). The big one has been Acrobat Pro X, but some of the features I have been counting on are now in Acrobat Reader and others are available as free web utilites. Worst case is I subscribe for a month if there’s something I HAVE TO have.
Sorry for the long Mojave/Catalina digression.