bug#14942: 24.3.50; Improve key descriptions for facemenu menu items

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Fri, 29 Apr 2016 15:18:17 +0200
> Cc: 14942@debbugs.gnu.org
> 
> Drew Adams <drew.adams@oracle.com> writes:
> 
> > `C-h f facemenu-set-invisible' says that the command is bound to
> > <C-down-mouse-2> <sp> v, <menu-bar> <edit> <props> <sp> v.
> 
> [...]
> 
> > This would be a lot more helpful for users if we simply used reasonable
> > names for the menu-item pseudo-function keys.  Instead of <sp> use
> > <special-properties> and things suddenly become much clearer.
> 
> What is <sp> meant to express, anyway?  I thought perhaps it was a
> keyboard shortcut, but nothing I press after C-down-mouse-2 seem to do
> anything...
> 
> And neither does the v.

Use the source, Lars:

  (defvar facemenu-special-menu
    (let ((map (make-sparse-keymap "Special")))
      (define-key map [?s] (cons (purecopy "Remove Special")
				 'facemenu-remove-special))
      (define-key map [?t] (cons (purecopy "Intangible")
				 'facemenu-set-intangible))
      (define-key map [?v] (cons (purecopy "Invisible")
				 'facemenu-set-invisible))
      (define-key map [?r] (cons (purecopy "Read-Only")
				 'facemenu-set-read-only))
      map)
    "Menu keymap for non-face text-properties.")
  (defalias 'facemenu-special-menu facemenu-special-menu)
  [...]
  (let ((map facemenu-menu))
    (define-key map [in] (cons (purecopy "Indentation")
			       'facemenu-indentation-menu))
    (define-key map [ju] (cons (purecopy "Justification")
			       'facemenu-justification-menu))
    (define-key map [s2] (list (purecopy "--")))
    (define-key map [sp] (cons (purecopy "Special Properties")  <<<<<<<<<
		    ^^^^       'facemenu-special-menu))
    (define-key map [bg] (cons (purecopy "Background Color")
			       'facemenu-background-menu))
    (define-key map [fg] (cons (purecopy "Foreground Color")
			       'facemenu-foreground-menu))
    (define-key map [fc] (cons (purecopy "Face")
			       'facemenu-face-menu)))