RE: indicating start and end of an overlay?

[Drew Adams]

Got no reply about this. The recent thread "no good way to highlight
rectangle while region is highlighted" reminded me of this, for some reason.

> From: Drew Adams Sent: Sunday, April 29, 2007 10:59 AM
>
> Can anyone think of a way in Emacs, today, to visually indicate the start
> and end of an overlay or a stretch of a face text property, as
> suggested by
> the little red corners in the first attached image? Notice the part
> highlighted in yellow, which shows two adjacent blue highlights. (This is
> from http://graphics.csail.mit.edu/~rcm/chi04.pdf, which Herbert/Guanpeng
> cited in his email today: "A prototype of intelligent replace for Emacs".)
>
> IOW, how might one, today, indicate two adjacent overlays (or
> text-property
> zones), so that a user can see the boundaries of each? Is this
> possible? If
> not, how might Emacs be made to support this (after the release)?
>
> Such "corners" would be useful. If it were not feasible to
> implement such a
> feature, could we perhaps implement something similar using box faces with
> borders? That is, could we have a way to make a bordered-box face show the
> vertical border at each overlay beginning and end? See the second attached
> image for what I mean.
>
> Today, if I use a box face with a border, and I create an overlay
> from L to
> M and another overlay from M+1 to N, then the appearance is the same as a
> single overlay from L to N. It would be useful to be able to specify that
> the two overlays each show their vertical borders at beginning
> and end. This
> wouldn't be as clear as having corners, as in the first screenshot, but it
> would still be useful.
>
> WDOT?

throw-overlay-beg-end.png
Description: PNG image

throw-overlay-beg-end-2.png
Description: PNG image