Subject: bug#28855: 26.0.90; display-line-numbers-mode does not respect (line|wrap)-prefix '(space :align-to N) text property

From: Dmitry Gutov <[email-masked]>
Date: Wed, 18 Oct 2017 12:29:08 +0300

Hi Eli,

On 10/16/17 7:05 PM, Eli Zaretskii wrote:

> When this was briefly discussed during development, we decided not to
> change the reported window dimensions and geometry, including those of
> the text area, to account for the screen estate taken by the
> line-number display.

FTR, I'd have preferred for the line numbers to be considered outside of 
the window edge, together with fringes and margins. And I still don't 
see any downside to it (except it might be harder to implement).

As it is now, third-party code has to adapt instead, by handling the 
line numbers specially.

> But maybe :align-to should be an exception, when
> used to align buffer text (as opposed to header-line or mode-line)?
> Though I'm bothered whether some users of :align-to may not want this
> automatic offset.  :align-to is a very popular feature; does anyone
> know or imagine why a Lisp program would NOT like such an offset?
> 
> What do people think?  Dmitry, what about company-mode popups, for
> example?

Not sure. What about them? We don't use align-to in the popups (though 
we could, for space-only offsets, now that I've read about this spec; 
not sure if the change will be worth it, performance or memory-wise).

And as for align-to's used in the buffer text, we probably don't support 
them very well, but the proposed change shouldn't make it any worse, I 
think.