Re: The unwarranted scrolling assumption

[Lennart Borgman]

On Thu, Jun 17, 2010 at 9:08 PM, Eli Zaretskii <address@hidden> wrote:
>> From: Lennart Borgman <address@hidden>
>> Date: Thu, 17 Jun 2010 20:44:26 +0200
>> Cc: address@hidden
>>
>> - The path try_scrolling is not taken.
>> - This is because clip_changed is 1.
>> - narrow_to_region set it to 1.
>> - reconsider_clip_changes gets a chance to reset it to 0, but it does
>> not in this case.
>> - reconsider_clip_changes does not however set it to 1.
>>
>> The reason that reconsider_clip_changes does not set clip_changed to 0 is 
>> that
>>
>>    !NILP (w->window_end_valid),
>>
>> which looks like window_end_valid is non-nil.
>
> Thanks, this is a start, but something is still missing.  We have this
> code at the beginning of reconsider_clip_changes:
>
>  if (b->clip_changed
>           && !NILP (w->window_end_valid)
>           && w->current_matrix->buffer == b
>           && w->current_matrix->zv == BUF_ZV (b)
>           && w->current_matrix->begv == BUF_BEGV (b))
>    b->clip_changed = 0;
>
> So, if b->clip_changed is non-zero at entry to reconsider_clip_changes,
> and w->window_end_valid is non-nil, as you say, this code should have
> reset b->clip_changed to zero.  And yet you say it didn't.  Why not?
> what prevented it from doing so?

I thought so first too, but please see the message I just sent with an
explanation of the patches I sent.

There might be some problem in the part above too, but my patches are
for another part of the problem. However the first question I gave to
you in the message I mention above may be a bit related to what you
ask here.