Re: Set-window-vscroll sometimes doesn't work

[Eli Zaretskii]

> From: Yuan Fu <casouri@gmail.com>
> Date: Thu, 22 Oct 2020 15:33:40 -0400
> Cc: help-gnu-emacs@gnu.org
> 
> >> With emacs -Q? On my machine emacs -Q doesn’t to that. Instead of moving 
> >> two line’s height, it just jumps
> >> to the next logical line.
> > 
> > That can only happen if the image fits in the window in its entirety.
> > Enlarge it so it's taller than the window, and then try again.
> 
> In the video I first pressed C-n a couple times, then C-u 2 C-n. It really 
> doesn’t smooth scroll here (I’m on master).

Please submit a full bug report, with the image to use, the Lisp code
to create the buffer you used, and anything else required to reproduce
the problem.

FTR, in my testing, I just visited an image file, enlarged it to be
larger than the window, and then invoked C-n with a numeric argument.
Your buffer has more stuff, which might make a difference.