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

[Stefan Monnier]

>> First of all, it already does. The difference comes up only when Emacs 
>> is too busy to re-render.
> No.  If you type C-n twice fast enough, Emacs will behave the same as
> if you type C-2 C-n.


Actually, I think if Emacs is "idle" before typing those two `C-n`,
Emacs will not behave the same as `C-2 C-n` unless they really reach
Emacs at the same time (which seems almost impossible unless you're
doing it over something like an SSH connection where some delay might
end up bundling them together).  This is because the `input_was_pending`
var is set at the *beginning* of processing the first `C-n` and at that
point, the second should not have arrived yet.  So AFAICT the redisplay
between the two will not be skipped.

If you do `C-n C-n C-n` quickly, the redisplay between the second and
the third might very well be skipped, OTOH (since the second and third
`C-n` might arrive while we're processing the first, in which case
`input_was_pending` will be true when processing the second).

> And I don't see any point in continue arguing about this, since we
> have very different expectations and different perspective.  Let's
> agree to disagree.

Do you think my suggestion to "accumulate" `scroll-conservatively` when
redisplay is skipped might be acceptable (I don't actually know if it
will/can work, OTOH).


        Stefan