Function finish 

pub fn finish(pressed: Spot, double: bool, released: Spot) -> Action

Letting go of a press that never moved — the click.

It acts on what the press landed on rather than on what the release did, which is the only rule that can be right: the press is the aimed half of the gesture, resolved against the frame the reader was looking at when they aimed.

A confirmation is the exception, and it is the one surface where the worst case is irreversible: there both halves have to land in the same button. That single equality is the whole guard, and it is stronger than it looks — Spot::Answer exists only on a frame that drew a question, so a press made before the box appeared can never equal one, and a box arriving under a held button cannot be answered by the hand that was already down.