bug#42406: Mouse-wheel scrolling can be flickering

[Alan Third]

On Tue, Dec 15, 2020 at 08:59:35AM +0100, martin rudalics wrote:
> >> Perhaps I should get rid of the internal border code, it's new to the
> >> NS port in Emacs 28.
> >
> > You could definitely make it optional, so that people who'd like
> > faster redisplay could decide whether they are okay with giving up the
> > internal border.
> 
> I haven't looked into it but can't running that code be simply
> suppressed when no internal border should be drawn anyway?  That is,
> when the width is zero which should be the default.

The default is 2 on the NS port, and on non-GTK X builds it would
appear to be 1.

I'm inclined to just leave it as-is. If people want to try setting it
to zero themselves they can, because as you say it doesn't do anything
if it's 0.
-- 
Alan Third