No undo for DEFINEKEY

[chrisws]

https://www.syntaxbomb.com/index.php/topic,7519.0.html

"Say I want to interrupt a loop with a key press, diverting to some other routine, which is possible with something like
DEFINEKEY ASC("p"), mySub
in the initialisation section. Now, when I tap the 'p' key, it diverts to mySub as expected.

I can exit the subroutine in the usual ways. I can PAUSE (without argument) and hit another key to continue to END (the sub), but I can't hit 'p', or it diverts immediately to the sub again. It would be neat if I could return to the main loop by a second press of 'p'. Even more of a problem is that no press of 'p' doesn't get grabbed by the interrupt, so you can't pause the loop and ask for input, or if you do and enter a 'p', you're back to the start of the subroutine.

What's needed is an UNDEFINEKEY asc("p"), or DEFINEKEY asc("p"), ""
but those don't seem to work.

I've tried a few possible solutions, including starting the subroutine with a new definition to a dummy subroutine, but it seems to be ignored (although you can define other keys inside a sub). It seems once defined, that's it, it stays defined.

I thought I had it when I made the pause routine just toggle a variable, running, testing for running=0 in the main loop and diverting to a second subroutine for the inputs, etc. This avoids the immediate interruption of input, but control appears still to be diverting to the toggle subroutine each time a p is pressed, so 2 (or any even number of) presses and when I finish input, it pauses again, any odd number in the input string and running is true again, so it's still not a solution.

Any thoughts...apart from maybe just using single key presses to interrupt the loop that aren't going to be used elsewhere, but there's not many to choose from. I can pause with a backspace, say, and exit the mySub with ESC."