bug#29711: 25.2; mode-line distortion when using :box on mac os

[Alan Third]

On Thu, Dec 14, 2017 at 08:42:44PM +0100, Charles A. Roelli wrote:
> > >> 1. Paste and then evaluate the following in the *scratch* buffer:
> > >> (set-face-attribute 'mode-line nil
> > >>                    :foreground "white"
> > >>                    :background "red" 
> > >>                    :box '(:line-width 5 :color "red"))
> > >> (setq-default mode-line-format (list 
> > >>              '(:eval mode-line-position)
> > >>              mode-line-modes))
> > >> 2. Open a long file that has thousands of lines. I used ivy.el which is
> > >> around 4k lines.
> > >> 
> > >> 3. Observe the mode-line is "distorted" like so: 
> > >> https://i.imgur.com/qxAsdfm.png
> > >> 
> > >> 
> > >> 
> > >> In GNU Emacs 25.2.1 (x86_64-apple-darwin16.6.0, NS appkit-1504.83 
> > >> Version 10.12.5 (Build 16F73))
> > >> of 2017-08-09 built on d12frosted.local
> > > 
> > > Doesn't happen here on macOS 10.6.  (For a "long file", I used M-x
> > > find-library simple RET).  Could you please try from emacs -q?
> 
> Thanks.  I see "Bot L8984(Emacs-Lisp ElDoc)", as attached, but I don't
> see where the problem is.

Hi,

I can replicate this in Emacs 25, but not the master branch, so I
believe it’s fixed. Upgrading to Emacs 26 should fix it.

See bug#23755:

    https://debbugs.gnu.org/cgi/bugreport.cgi?bug=23755
-- 
Alan Third