bug#6671: moving point and scroll-conservatively

[Eli Zaretskii]

> From: Juanma Barranquero <lekktu@gmail.com>
> Date: Tue, 29 Mar 2011 01:00:00 +0200
> Cc: cyd@stupidchicken.com, 6671@debbugs.gnu.org
> 
> [Sorry, I somehow missed your answer yesterday]
> 
> On Sun, Mar 27, 2011 at 05:59, Eli Zaretskii <eliz@gnu.org> wrote:
> 
> > That's good to hear.  Please see if it still works great after fixing
> > a stupid mistake with parentheses (see my other mail this morning).
> 
> Yes, it works great. Please install it.

I will in a couple of days.  I'm still working on minor issues related
to scrolling due to cursor motion (e.g., it was totally screwed up
when scroll-*-aggressively is set) and on code in try_scrolling that
cannot be anything but wrong, like this one:

          if (arg_scroll_conservatively)
            amount_to_scroll
              = max (dy, FRAME_LINE_HEIGHT (f) * max (scroll_step, 
temp_scroll_step));

Huh? we're under scroll-conservatively, but don't consider its value
for scrolling?

> > In what sense is that "bad"?
> 
> emacs xdisp.c    ;; not -Q, but with my setup
> PgDown             ;; keep pressed
> 
> It scrolls for a while, then stops for a while, then jumps ahead
> (sometimes, hundreds or thousands of lines).

Ah, that one.  Yes, I see it.  I think that's because scroll-up uses a
heavy algorithm.  But its implementation is entirely separate from
what I was trying to fix, so it's expected that scroll-up and
scroll-down won't be affected.

> > And by "scroll-up-command" do you mean `scroll-up' and `scroll-down'?
> 
> No.
> 
>  emacs -Q
>  C-h k PgDown
> 
> <next> (translated from <kp-next>) runs the command scroll-up-command,
> which is an interactive compiled Lisp function in `window.el'.

I was talking from Emacs 23.  But anyway, the difference is small,
because scroll-up-command just calls scroll-up.