popping property

Whether the transition is a pop — an animated pop, a back-swipe, or the exit a committed swipe plays out.

A pop plays the same forward choreography as a push, toward the other target: flowProgress mirrors the clock and flowFrom/flowTo swap the roles, so the swell leads and the bounce lands with the page in both directions. Rendering the push in reverse instead put all the motion at the wrong end of a pop.