bug#10105: 24.0.91; Possible bug in `scroll-conservatively'

[Eli Zaretskii <eliz@gnu.org>]

> From: Juri Linkov <juri@jurta.org>
> Cc: Eli Zaretskii <eliz@gnu.org>,  10105@debbugs.gnu.org
> Date: Tue, 29 Nov 2011 09:05:04 +0200
> 
> > 1. Eval: "(setq scroll-conservatively 101)".
> > 2. Eval: "(custom-set-faces '(mode-line ((t (:box (:line-width 1))))))".
> > 3. Visit the attached file.
> > 4. Type "C-s p C-s C-s C-s".
> > --> At this point, the Isearch has moved point to line "p1", but it's
> > positioned at the top of the window.  It should be at the bottom.
> 
> I've just noticed that Firefox behaves exactly the same as Emacs.
> When typing repeatedly `F3' and wrapping around to the beginning
> of the Web page, the search string is highlighted and positioned
> at the top of the Firefox window, not at the bottom.  Firefox imitates
> Emacs-like Isearch.  So we should not disappoint users by changing
> the traditional behavior in Emacs.

I agree with your conclusion, but for the record I'd like to point out
that what you see in Emacs 24 is not the traditional behavior, not in
this case.  All versions of Emacs before 24 would not keep point at
the first or last screen line, they would sooner or later center point
in the window.  Emacs 23.3, in particular, centers point already after
the first "C-s p"; Emacs 22.3 centers it after the next C-s.

Only Emacs 24 behaves consistently when scroll-conservatively is set
to a large value.  IOW, the default "recentering" is now completely
replaced with code that puts point on the first or last line in the
window (barring bugs, of course) when this variable is set.