Re: The unwarranted scrolling assumption

[Lennart Borgman <lennart.borgman@gmail.com>]

On Tue, Jun 22, 2010 at 12:06 AM, David De La Harpe Golden
<david@harpegolden.net> wrote:
> On 21/06/10 03:59, Eli Zaretskii wrote:
>>>
>>> Date: Sun, 20 Jun 2010 22:40:44 +0100
>>> From: David De La Harpe Golden<david@harpegolden.net>
>>> CC: emacs-devel@gnu.org
>>>
>>> window.c: Still recentering sometimes.
>>
>> Does the problem go away if you disable font-lock-mode?
>>
>
> I could not reproduce today without font-lock-mode on two complete
> scrollthroughs (one with redisplay-dont-pause and one without).
>
>
> font-lock-mode on:
>
> redisplay-dont-pause nil (that's nil):
>
> I counted about 114 visible recenters on one complete scrollthrough (N.B.
> definitely recenters i.e. cursor restarting from the middle, not just update
> lags),
>
> redisplay-dont-pause t (that's t):
>
> No visible recenters on one complete scrollthough.


I think you must close and open the file before each such test.

The reason is that font lock calls some of the narrowing functions and
that will cause recentering (because clip_changed will be set to 1).
And when you have scrolled through the whole file it is fontified so
the next time you test you will not see this particular problem.