bug#44120: 28.0.50; Animated GIFs sometimes leave "trails"

[Lars Ingebrigtsen]

M-x eww RET 
https://lh4.googleusercontent.com/TQ10szluPdXsKoYIeYe5ljxjVIoJzcCvLybUa3tEA24a6vISYkwiqAz9VymzgyNY_N8tfqHKvxSv9WhrcC-GvDc4uaiCE1T52y3C6xK1K--Lazicm9PSBiGxGVCyjFtDTBJaEOuExA

will give you an animated GIF that displays the problem: It seems like
when repainting, the previous area that has changed isn't reset...  or
something.

We're probably not following the GIF animation standard when applying
the deltas?  


In GNU Emacs 28.0.50 (build 119, x86_64-pc-linux-gnu, GTK+ Version 3.24.23, 
cairo version 1.16.0)
 of 2020-10-21 built on xo
Repository revision: 4ef8c4a0f4e26f6ea2186a2b80c068b8d93e4993
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Debian GNU/Linux bullseye/sid

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no