bug#21750: show-paren-mode erroneously highlights the left margin

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 25 Oct 2015 01:53:34 +0200
> From: Hinrik Örn Sigurðsson <hinrik.sig@gmail.com>
> Cc: 21750@debbugs.gnu.org
> 
> > You can work around this in this case if you modify your face
> > customization as follows:
> >
> >     (custom-set-faces
> >       '(linum ((t (:foreground "black" :background "white" :weight bold)))))
> >
> > IOW, don't let the 'linum' face inherit the background color from the
> > surrounding text.
> 
> Unfortunately that doesn't work in my case.

By "don't work" what exactly do you mean?  Do you still see the
greenish background of the show-paren face on the line numbers?  Or do
you see something else?

> The desired background color is pure black (#000000). However both
> "black" and "#000000" result in Emacs choosing the 1st color of the
> terminal's 16-color palette, even when running in 256-color mode.

That's a different issue, but I think it, too, can be solved, see
below.

(Btw, I wonder why you use a black foreground for this face if your
background is also black.  What am I missing here?)

> Though pure black is my terminal's default background color (which
> is independent of the palette), it is not present in the 16-color
> palette.

That's strange: are you saying that a 16-color xterm doesn't have
"black" among the colors it supports?  I don't think I've ever seen
that; perhaps the settings for xterm on your system deliberately
define "black" as something whose RGB value is not #000000?

> So there's no way of explicitly specifying this background color in
> Emacs unless I change my terminal's color palette, which would affect
> the appearance of other terminal programs.

What happens if you specify the 'linum' face to inherit the background
from your 'default' face, like this:

  (custom-set-faces
   '(linum ((t (:inherit default :foreground "black" :weight bold)))))

Does this produce good results?