do you recall BZ 465345, NetworkManager GUI for bonding / bridging? This feature has now been in Fedora for some time, and I am desperately trying to get it to work on my laptop. But either the implementation is totally broken, or I'm too dumb to set it up correctly. Unfortunately I can't give precise error descriptions, because the systems behaves erratically.
1) NM presents "wired" and "bridge" interfaces. Is it necessary to delete the "normal" wired interfaces when briding is intended to be used? What if the user wants bridging sometimes, but not always? Btw deleting an interface profile doesn't seem to be possible through the GNOME GUI, at least not as non-root user.
2) GNOME nm-applet does not recogize the bridge - if only the bridge is up, it considers the system "offline" (offline symbol in GNOME panel).
If you have time, could you experiment with this a little? I'm just too confused to write a bug report on this.