I believe that is an OS routine, and so can't be kept track of by Axe

Is it a custom image or is it actually a progress bar?

Oh dear. I really despise the attitude that, because it can be done with other commands, there is no reason to make a new command for something, even if the new command would be much faster and lead to smaller code.
Oh look, the z80 doesn't have a multiply instruction! Eh, let's leave it to the Axe prgrammers, surely they won't mind!
Oh, wait, that's exactly what didn't happen. Thanks Quigibo!

But doors can also have a custome Garbage Collection image.....

Doors CS uses some clever hacks involving hooks to just be able to skip the confirmation screen and draw an image. Tracking the progress would require somehow knowing what the GC routine is doing while also redrawing the image, which as far as I know simply isn't possible with hooks.

You just invert and multiply. So to divide A by B, one simply does B^-1**A.

How about -abs()

While were's on the subject, how about a command that determines the sign of a number.  I.E., anything over 32218 (I think) would return 65535 (-1), anything between that number and zero would return 1, and zero would return 0.  I remember 86 Basic had it and it was a nice command.