bug#22404: 25.1.50; Forcing `window-scroll-functions` to run.

[Eli Zaretskii]

> Date:  Tue, 09 Feb 2016 08:00:33 -0800
> From:  Keith David Bershatsky <esq@lawlist.com>
> Cc:  22404@debbugs.gnu.org
> 
> The issue mentioned in my last email was caused by `font-lock-mode` -- when I 
> turn off `font-lock-mode`, there are a few situations where point remains 
> partially visible at the bottom of the window and redisplay does not catch it 
> -- e.g., when the line that point is on is about 90 percent visible at the 
> bottom of the window.

Did you define faces that change more than just the colors, like use a
different font or bold/italic typefaces?  If so, what you see might
not be a bug: the original display is before JIT font-lock kicks in
and changes the dimensions of the characters on display, so they are
partially visible only after fontifications did their job.