Re: set-window-start in Elisp manual

[Stephen Berman <Stephen.Berman@gmx.net>]

On Thu, 17 Jan 2008 15:29:01 +0100 bojohan+news@dd.chalmers.se (Johan Bockgård) wrote:

> martin rudalics <rudalics@gmx.at> writes:
>
>> FWIW this used to work in Emacs 20 but was already broken in Emacs 21.
>> We would have to find out why and where `window-start' gets reset to 1.
>
>       [xdisp.c:13049]
>
>       /* If window starts on a continuation line, maybe adjust the
>          window start in case the window's width changed.  */
>       if (XMARKER (w->start)->buffer == current_buffer)
>         compute_window_start_on_continuation_line (w);

How does this piece of code relate to the set-window-start issue, since
the latter doesn't seem to involve a continuation line?  Or did you
accidentally paste in the wrong bit, and really mean the following
(which is at xdisp.c:13049 in my sources from yesterday; the above is at
line 12966):

  /* If window-start is screwed up, choose a new one.  */
  if (XMARKER (w->start)->buffer != current_buffer)
    goto recenter;

I cannot tell, because I don't understand the code.  I would be grateful
for any elucidation anyone cares to give.  In particular, I would like
to understand an apparent restriction on window-start in conjunction
with display properties.  I've posted several times about this, but the
only response I've gotten was from RMS (see
http://permalink.gmane.org/gmane.emacs.devel/86019), which was too terse
for me to really understand.  If someone who does understand it has the
time to elaborate, I would be most grateful.

Steve Berman