bug#6113: 23.1.97; doc of :box face attibute

[Drew Adams]

emacs -Q
 
Visit node Face Attributes in the Elisp manual.
 
The description of attribute :box does not say what the possible values
of :line-width are or what they mean.
 
Take a look at face `mode-line-inactive', for instance.  It has a
`line-width' of -1.  There is no way to understand this unless it is
documented properly.  Even for positive values, we say nothing about
what the width units are (e.g. pixels).
 

In GNU Emacs 23.1.97.1 (i386-mingw-nt5.1.2600)
 of 2010-05-04 on G41R2F1
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --no-opt --cflags -Ic:/xpm/include'