Re: display margins and modifying the buffer

[Alloy Petrofsky]

> From: address@hidden (Juanma Barranquero)
> 
> From a two-month old discussion regarding display margins, overlays,
> text properties and line numbers:
> 
> Me:
> 
> > but setting the display property of the overlay to show anything
> > in the margin makes the text covered by the overlay go invisible;
> 
> Stefan Monnier:
> 
> > if you use overlays, it's not a big problem since you can make
> > your overlay span 0 chars.
> 
> Finally I've had the time to try it and it does not work: overlays of
> length 0 do not show anything in the margin. Making the span at least
> length 1 does make the margin text appear, at the cost of making
> invisible the text covered by the overlay.

There are two solutions:

  (1) Put a one-character overlay on each newline, and give this
  overlay both a marginal display property and an after-string
  property of "\n".

  or (2) Give a zero-length overlay an after-string property of some
  random string, and then put a marginal display property on the
  string.

Mention of the second option was added last month to the info node
(elisp) Display Margins.

-al