"What does this mean? Well, if this is approved, GNOME Shell
will get AppIndicator support so all those cool Ubuntu
AppIndicators will work in GNOME Shell.
"The AppIndicators will show up in the GNOME Shell Message Tray
(displayed at the bottom of the screen) and they work a bit
differently compared to the Ubuntu implementation: clicking the
notification brings the application forward (if the AppIndicator
isn't a stand-alone app), the menu shows up on right click and they
support tooltips, as opposed to Ubuntu. But of course, this may
change (again, if this is approved)."