scrolledwindow: Accumulate velocity with kinetic scrolling
Backport !2768 (merged) to GTK3.
CC @Cwiiis1
Accumulate existing velocity when decelerating from a swipe if the swipe velocity is above a certain fraction of that existing velocity.
Backport !2768 (merged) to GTK3.
CC @Cwiiis1
Accumulate existing velocity when decelerating from a swipe if the swipe velocity is above a certain fraction of that existing velocity.