Suggestion: on iPhones, long-press toggles undo/redo button?

Suggestions
1

@Simeon: The rapid-undo button is a G-DSEND on iPhones

And I get that there’s
precious little toolbar real-estate for a rapid-redo button.

But what if a long press on the rapid-undo button gave you the option to turn it into a rapid-redo button?