bug#23468: Feature request: highlight Edebug breakpoints

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: pogonyshev@gmail.com,  23468@debbugs.gnu.org
> Date: Mon, 21 Oct 2019 22:29:27 +0200
> 
> By cargo-culting the code from gdb-mi, I get the following way to make
> an overlay that's not hiding anything in the buffer, but just showing a
> fringe bitmap:
> 
>  (let ((fringe (make-overlay pos pos)))
>    (overlay-put fringe 'before-string
>                 (propertize "x" 'display `(left-fringe breakpoint 
> ,face)))))))))

Yes, that's it.