bug#17612: 24.3; Negative :box line-width still affects width

[Eli Zaretskii]

> From: Patrick Hurst <phurst@mit.edu>
> Date: Tue, 27 May 2014 16:31:02 -0400
> 
> According to the documentation, setting the :line-width attribute on a
> face to a negative value 'avoid[s] any increase in the character height
> or width'. However, when I set it it does increase the width as if the
> value were positive.
> 
> To replicate: open a new .org file, type in "* TODO Foo" and execute
> 
> (set-face-attribute 'org-todo nil :box '(:line-width 4))
> (set-face-attribute 'org-todo nil :box '(:line-width -4))
> 
> Note that the "Foo" doesn't move, implying that the width of the "TODO"
> doesn't change.

This is bug #13011.  See there for the discussion of why the code was
written to behave like that, and some situations where what you expect
has unpleasant side effects.