Re: Fringe in Show/Hide menu?

[Eli Zaretskii <eliz@is.elta.co.il>]

On Mon, 1 Apr 2002, Pavel =?iso-8859-2?q?Jan=EDk?= wrote:

> +(define-key menu-bar-showhide-fringe-menu [right]
> +  '(menu-item "On the Right" 
> +	      (lambda ()
> +		(interactive)
> +		(toggle-fringe 'right-fringe))
> +	      :help "Turn fringe on the right on/off"
> +	      :visible window-system

Please try to avoid using window-system as much as you can.  In this 
case, it is actually incorrect, since the MS-DOS port defines a non-nil 
value for window-system (for histerical reasons).  More generally, use
of window-system is a time bomb: as Emacs is developed and features that
were once available to certain kinds of displays are made available on 
more display types, the places that use window-system become maintenance 
burden, in the need for constant attention, and a source of bug reports.

It is better to condition such menu items on some feature or function 
that is required for the underlying functionality to work.  For example, 
(fboundp 'some-function-required-for-fringes) could be a good test in 
this case.  If all else fails, display-graphic-p is still better than 
window-system.