bug#46320: 27.1; bugs about scrolling buffer with images

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Fri, 05 Feb 2021 10:22:15 +0100
> Cc: 46320@debbugs.gnu.org
> 
> > (2)unable to scroll up
> > Evaluate the form below and type C-v repeatedly, the buffer never scroll
> > up to the end of the buffer. Once in three times, the buffer scrolls
> > down and the line 2 is displayed at the top of the window.
> 
> ... and I'm unable to reproduce this problem (on Emacs 27.1 and Emacs
> 28), but I think there's a good chance that this has also been fixed by
> Eli's fixes in this area.  Would it be possible for you to test this in
> Emacs 28?

I already did, and I do see the behavior described in the OP.  I'm
guessing you will see it as well if you play a little with the font
size.

I will look into this when I have time.  It isn't a new problem, so
there's no rush.  Redisplay's behavior in the presence of tall images
and small windows was always problematic, and the workaround is easy
enough.