Re: setnu.el / setnu+.el

[Kevin Rodgers]

Stefan Monnier wrote:
> > Instead of setting the overlay's before-string property to "...", I
> > tried setting its display property to ((margin left-margin) "...") plus
> > the left-margin-width variable to the length of "...".
>
>
> Yes, the use of the display property for such uses is somewhat odd: you have
> to use a (dummy) before-string (or after-string) property on an overlay and
> place the `display' property on that string.  The dummy string should have
> length >= 1.
>
> Typically the code looks something like:
>
>   (let ((ol (make-overlay start end))) ;; start can be equal to end if you want
>     (overlay-put ol 'before-string
>                  (propertize " " 'display
>                              <the intersting stuff>)))
>
> See for instance the code of put-image.

Yes, the way put-image works is well-documented, in both its doc string
and the Emacs Lisp manual.  But the fact that the display property
doesn't work unless it's a text property of an overlay's before- or
after-string is not documented.

That the display property doesn't work as expected seems to me to be a
bug, and it's definitely a documentation bug that the way to get it to
work is only described in regards to the put-image function.

Thanks,
--
Kevin