Re: Scrolling commands and skipping redisplay, was: Re: emacs rendering comparisson between emacs23 and emacs26.3

[Eli Zaretskii]

> Cc: address@hidden, address@hidden, address@hidden, address@hidden,
>  address@hidden
> From: Dmitry Gutov <address@hidden>
> Date: Mon, 20 Apr 2020 20:04:06 +0300
> 
> >> The fact that Emacs's behavior can depend on when redisplay happens, and
> >> the user cannot reliably control it, is problematic IMHO.
> > 
> > Please be specific: what Emacs's behavior can depend on when redisplay
> > happens, apart from whether something was or wasn't updated on
> > display?
> 
> The window's scroll position.
> 
> Again: you (setq scroll-conservatively 1) and lean on C-n for a little 
> while. Depending on whether Emacs manages to redisplay after every 
> command invocation, the point will, or will not, scroll to the middle of 
> the window. It could do that several times as well.

Yes.  because that's what scroll-conservatively = 1 means.

> >> Then give up and move point to the middle of the window.
> > 
> > But that's again "not good" according to your opinion, isn't it?
> 
> Why wouldn't my suggestion be good enough?

Because you don't want to see recentering, ever:

> > Or
> > maybe you assume this will solve most of the cases when we currently
> > recenter under scroll-conservatively < 101?
> 
> All important ones, yes.

See? so set scroll-conservatively to 101, and Bob's your uncle.  Yours
truly has worked hard and long to have that never recenter, including
in some exotic use cases.