bug#6671: moving point and scroll-conservatively

[Juanma Barranquero <lekktu@gmail.com>]

On Thu, Mar 24, 2011 at 22:47, Chong Yidong <cyd@stupidchicken.com> wrote:

> This means that any time point moves below the bottom of the window, the
> resulting scroll will leave the cursor at the bottom of the window.  Any
> time point moves above the top of the window, the resulting scroll will
> leave the cursor at the top of the window.  Unlike numerical values of
> scroll-conservatively, there is no "scrolling limit" to check.

In other words, `scroll-conservatively' set to t means "scroll
line-by-line", or "scroll but never recenter". I'm OK with that (well,
I'm much more than OK; that's what I consider the only sane behavior
of scrolling, and what many other text editors do, though I readily
admit that most Emacs users seem to prefer the recentering behavior).

But the trick is making it fast enough, isn't? IIRC, the current
sluggish performance and some other changes were brought in to cope
with redisplay pausing for a while and then suddenly "jumping ahead"
in the buffer because it wasn't fast enough to keep up with typematic
repeat during scrolling (pre-Unicode2 merge it always was,
post-Unicode2 scrolling line-by-line is jumpy the best of days,
specially when moving up the beginning of the buffer).

    Juanma