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

[Dmitry Gutov]

On 16.04.2020 08:22, Eli Zaretskii wrote:
> > Scrolling is certainly special at least in some way:
> >
> > - Implementation-wise, not all commands simulate redisplay during their
> > operation.
> I think you will find that many more do than you seem to assume.  Even
> just redisplaying a window does this in many cases (to find the proper
> place for window-start position).  C-n and C-p do as well.  And when
> scroll-conservatively is in effect, almost every command that moves
> point does.

Would that be... almost all of them?

(Indeed, the fact that (setq scroll-conservatively 1) doesn't work as 
well as one would expect is a real bug IMO).

In any case, if there is a way to dynamically detect these cases and 
disable redisplay skipping for them, I'd like to try that out.

Even more if there was a way to put the results of "simulated redisplay" 
to use in the "real" redisplay later.