Re: Smoother macOS touchpad scrolling

[Tak Kunihiro]

> +(setq mouse-wheel-scroll-amount '(1 ((shift) . 5)))
> +(setq mouse-wheel-progressive-speed nil)

I thought one of good things about your patch is to make scrolling smooth
without changing default.  No?

  http://lists.gnu.org/archive/html/emacs-devel/2017-08/msg00624.html

> +          int lineHeight = default_line_pixel_height(XWINDOW 
> (FRAME_SELECTED_WINDOW (emacsframe)));

A buffer with images has lines with different height.
I think lineHeight should be
 - height of 1 line (or sum of 5 lines) at the top on a screen
   when scrolling up
 - height of unseen 1 line (or sum of unseen 5 lines) above the
   top out of screen when scrolling down.