But you could do that with any key (except for one you want to use for something else, obviously!). Go wild -- plug in an external Apple Extended Keyboard and have an extra 100+ USB Device key triggers to play with!
1 Like
I might be utterly wrong here, because of Device Key triggers passing through to the frontmost app, rather than being swallowed in the way that hot key triggers are. I'll have to find an external kb and have a play...
Yes, Nige, I didn't want to tell you so as not to disappoint you 
I'm also interested in this function 
Further to this whole "Fn is not a modifier" thing, it seems Apple is taking a more active role in “owning” the Fn key for its own purposes.
See:
https://mjtsai.com/blog/2023/05/02/fn-key-reserved-for-system-applications/
2 Likes
But it has got me wondering. I mean, the reason vi[m] can have single keys that either type letters or perform actions is the different modes.
All we need to do is enable/disable single-key triggered macros depending on what "mode" we put our Mac in...
Right. Another "mode" could be activated with a macro group or a palette. But how to do that without disturbing the normal writing flow?
If you write slowly, you can solve this well with a multipress macro. In this case letters are typed when releasing the key and macros are triggered when holding the key a little longer. For fast typists this is known to be a disaster. 
I wonder what it would be like if all letters were typed when the key is released. Theoretically, there shouldn't be any letter twists then. And you could easily trigger macros. But how does that feel for normal typing? Maybe I'll try that out 
The original question was how to imitate a shortcut with fn + letter. @noisneil has described the problem well. A solution with a palette does not work either. Unless you choose a string, which is not really a good solution.
This is only relevant if you use the Apple Keyboard Shortcuts system. 
Well, the real power of vi[m] "control keys" comes from being able to do things like 10j to go 10 characters back, 100l to go 100 lines down, etc. So while having to type something like Fn10j⎋ does break the flow, it's not as bad as mashing an arrow key multiple times.
Agreed and agreed. I'm off on another tack, for another time.
That's true, of course. The best you could do with KM would be a palette with single key triggers. For example, "0" would stand for 10 lines up. "0" long pressed for 10 lines down ... or something similar