In the transition class's render method, it seems that time_warp is applied after it calculates easein_time and center_warp. I believe time_warp should instead be applied before those two, because otherwise, easein_time and center_warp will be on a different timeline from the ripples.

Is it possible to have this affect the main displayables layer, but not screens? With() takes no layer argument, and Hide(screen="foo", transition=ripple, _layer="master") doesn't do it. I've wanted to create a ripple effect when choice options appear for ages and this looks perfect, but unfortunately ripples over the menu when it appears.