disabling slowkeys in gdm3

[Joe Pfeiffer <pfeiffer@cs.nmsu.edu>]

I've also run into the problem with slowkeys automatically turning
itself on when I hold the shift key too long, as described in

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=657969

It isn't clear to me why the display manager has anything to do with
this, but apparently the solution is to use gconf-editor to disable it
in gdm3.

If I start up gconf-editor, I don't see any configuration options for
gdm3 nor simple-greeting.  So far I've tried

gconf-editor
sudo gconf-editor
sudo -u Debian-gdm gconf-editor

(I should note that gdm actually runs as root on my system -- so I'm not
sure what the Debian-gdm user is actually for?)

My question, of course, is "what am I missing"?  What do I need to do to
make gdm3 configuration visible in gconf-editor?