Re: The unwarranted scrolling assumption

[Lennart Borgman]

On Thu, Jun 17, 2010 at 9:26 PM, Eli Zaretskii <address@hidden> wrote:
>> From: Lennart Borgman <address@hidden>
>> Date: Thu, 17 Jun 2010 21:14:04 +0200
>> Cc: address@hidden
>>
>> >  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.
>
> Sorry, that doesn't explain it to me, because narrowing is not part of
> the recipe at all.

You are making a bad assumption. Narrowing is happening during scrolling.

> Again, PLEASE answer my questions, if you really want my help in
> understanding this issue.  What parts of the above condition prevented
> reconsider_clip_changes from resetting b->clip_changed to zero?

Sorry, I thought I did tell that, but maybe I deleted that from some message.

It is !NILP (w->window_end_valid). There might be an error there too.

But it is not this that normally gives the "jumping scrolling". I am
not sure it is a problem at all.

> needed, please re-run under GDB (without your patches) and see what
> other factors are at work here.

Why should I do that?