First, thanks, it made me chuckle! I have no dog in this race, but it seems to me that a finger hook and stopper is a functional feature of the rotary dialer.

First, thanks, it made me chuckle! I have no dog in this race, but it seems to me that a finger hook and stopper is a functional feature of the rotary dialer. If and only if the user put their finger in the hole to dial, then the finger stop should catch and prevent the wheel from moving beyond that number. In other words, the number choice is actually strongly implied (but not locked in) the moment the finger is in a hole, and the stopper isn't merely an indicator but is step 2 of guiding that choice through. How best to simulate that distinction in a 2d screen, no idea...