Re: The unwarranted scrolling assumption

[Eli Zaretskii <eliz@gnu.org>]

> From: Lennart Borgman <lennart.borgman@gmail.com>
> Date: Thu, 17 Jun 2010 21:14:04 +0200
> Cc: emacs-devel@gnu.org
> 
> >  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.

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