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

[Eli Zaretskii]

[Please always CC the bug address.]

> From: Adam Simpson <adam@adamsimpson.net>
> Date: Thu, 14 Dec 2017 14:08:39 -0500
> 
> I will update the image. My mistake. Here is the correct link: 
> https://i.imgur.com/0mzkg3K.png
> 
> Notice the space between B and o in Bot.

That definitely doesn't happen here.  The :box face causes "Bot" to
slightly move horizontally when the mouse is moved above the mode
line, but here "Bot" moves as a single unit, and no space is left
between B and o.