bug#2993: 23.0.92; posn-col-row wrong with line-spacing in terminals

[Eli Zaretskii]

> From: Nikolaj Schumacher <me@nschum.de>
> Date: Tue, 14 Apr 2009 13:11:55 +0200
> Cc: 
> 
> posn-col-row uses the `line-spacing' value in terminals.  According to the
> doc `line-spacing' only has an effect in window systems.

You mean, on graphic displays.

> --- a/lisp/subr.el
> +++ b/lisp/subr.el
> @@ -934,7 +934,8 @@ and `event-end' functions."
>            (y (/ (cdr pair) (+ (frame-char-height frame)
>                                (or (frame-parameter frame 'line-spacing)
>                                       ;; FIXME: Why the `default'?
> -                                  (default-value 'line-spacing)
> +                                  (when (window-system frame)
> +                                    (default-value 'line-spacing))
>                                    0)))))
>       (cons x y))))))

Please use `display-graphic-p' rather than assuming that if
`window-system' is non-nil, the display is necessarily a graphic one.
At least one Emacs configuration violates this assumption.