bug#33864: 27.0.50; Display corruption with "small" font size when something is in the fringe

[Eli Zaretskii]

> From: Dale Sedivec <dale@codefu.org>
> Date: Tue, 25 Dec 2018 00:01:58 -0600
> 
> Using Emacs master with the NeXTStep interface on macOS, I get display 
> corruption on lines where features
> such as Flymake, Flycheck, or diff-hl display something in the fringe.  This 
> is a bit hard to describe, so I'm
> attaching a screen shot, and I've also made a short movie of this happening:
> 
> https://www.dropbox.com/s/h9eqixqxst4wg37/emacs_27_small_font_fringe_problem.mp4?dl=0

Looks like the cursor's line is being cleared without telling Emacs
about that.

Does it help to decrease the size of the Flymake's fringe indicators
when you switch to a smaller font?  From the screenshot it looks like
the indicator keeps its original size although the font becomes a lot
smaller.