bug#23468: Feature request: highlight Edebug breakpoints

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: pogonyshev@gmail.com,  23468@debbugs.gnu.org
> Date: Sun, 20 Oct 2019 19:18:11 +0200
> 
> > GUD puts a bitmap on the fringe for each breakpoint, yes.
> 
> Hm.  This is all pretty new to me...  but...
> overlay-arrow-variable-list is a list of variables, each of which can
> have one single position.

No, that's not it.  Sorry, I've misled you: you need to look at
gdb-mi.el, where it puts on an overlay string a display property whose
value includes 'left-fringe.  See, e.g., gdb-put-string.