Re: bug#9782: 24.0.90; move-to-window-line not taking header line into account

[Dmitry Gutov <dgutov@yandex.ru>]

Eli Zaretskii <eliz@gnu.org> writes:
>> From: David Engster <deng@randomsample.de>
>> Cc: 9782@debbugs.gnu.org
>> Date: Tue, 18 Oct 2011 16:23:37 +0200
>> 
>> My report was motivated by seeing that the tooltip display of
>> company-mode (currently in ELPA) broke due to the change in
>> posn-actual-col-row. Company-mode happens to depend on the above test
>> case, that means it first determines the actual row at point, moves to
>> (1+ row) through move-to-window-line and then displays the overlay
>> there. I don't know why it chooses this way to do this, but it has
>> worked for years, so I figured move-to-window-line has to be fixed.  If
>> this new behavior is the correct one, then please close this report and
>> I will send a bug report to the author of company-mode.
>
> I'm closing the bug report.  My opinion is that company-mode should
> either change the way it computes the line to move to, or account for
> the header-line itself (e.g., by looking at the value of
> header-line-format).  If the author of that package disagrees, I
> suggest that he or she starts a discussion on emacs-devel.

There you go, I'm starting the discussion.

What do you suggest would be a better way to get the window row of a
buffer position, save that value, and then move to that row later?

Currently, company calls (cdr (posn-actual-col-row posn)) to retrieve
the row, and `move-to-window-line' to get to it.

Simply adjusting the row number for presence of `header-line-format'
won't do, because company strives to support Emacs 23 (and maybe even
22), and `post-actual-col-row' behavior was different before the
revision 106022.

--Dmitry