bug#35740: 26.1; scroll bar jaggies / tearing

[npostavs]

Bob Hepple <bob.hepple@gmail.com> writes:

> When I drift the sprite (mouse cursor) in and out of emacs the scroll
> bar goes a little bit crazy with animated jaggies running up and down
> its length. No other window (eg terminals, firefox etc) shows this
> artifact.
>
> I've put up a video of the glitch at https://youtu.be/EMa1OWDhVS4. It
> shows both emacs -Q and plain emacs running.

Does disabling double buffering have any effect?

    (modify-all-frames-parameters '((inhibit-double-buffering . t)))