Smoother macOS touchpad scrolling

[Alan Third]

Attached is a patch to provide smoother scrolling with the touchpad on
macOS. It adds up the scrolling deltas and only sends a scroll event
when the total exceeds the frame’s default line‐height.

Scrolling quickly sometimes results in the screen stuttering a little.
I’m not sure if that’s just a result of scrolling quickly, or because
my code sends one scroll event for each line it wants to scroll and it
overloads Emacs redisplay or something.

Does anyone know if there’s a way, in C, to detect if we’re at the top
or bottom of the buffer? I’d rather not send momentum scroll events if
the buffer isn’t going to scroll.
-- 
Alan Third

0001-Provide-smoother-touchpad-scrolling-on-macOS.patch
Description: Text document