bug#27895: 26.0.50; display-line-numbers and header-line-format alignment

[Eli Zaretskii]

> Date: Tue, 01 Aug 2017 06:35:00 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 27895@debbugs.gnu.org
> 
> > From: Mark Oteiza <mvoteiza@udel.edu>
> > Date: Mon, 31 Jul 2017 21:35:48 -0400
> > 
> > Enabling display-line-numbers should affect how header-line-format is
> > shown.
> 
> I'm not sure I agree with this, not in this general form.  Modes use
> header-line in different ways, and I don't think we can decide for all
> of them up front how they should react to line numbers.
> 
> While I agree that tabulated-list modes and ruler-mode should indeed
> be sensitive to line numbers, because the header-line in those modes
> should align with the rest of buffer text, a counter-example is Info
> mode, where indenting the header-line will IMO make the display look
> uglier, almost buggy.
> 
> If people agree that the effect on header-line should be dependent on
> the mode, then it follows that the fix should be in the modes, not in
> the display engine.  Fixing tabulated-list-mode will fix all of its
> descendants; ruler-mode will need a separate fix.  And likewise for
> any other mode which reports a similar issue.

No further comments, so I've fixed tabulated-list-mode and ruler-mode
to be sensitive to display-line-numbers, and I'm boldly marking this
bug done.

Thanks.