Gnome 3 doesn't display systray java tray icons by default. When using the top icons plugin [the jajuk tray is displayed but clicking on it has no effect. It is a known issue 2. We should disable the tray under Gnome 3 but we didn't figure any way to differentiate Gnome2 (for which the tray works) and Gnome3.
Under Gnome 3, the full screen works but is overridden by the top bar.
Reported by bflorat on 24 Aug 2014 14:26 UTC
[https://extensions.gnome.org/extension/495/topicons/ 2 https://bugzilla.redhat.com/show_bug.cgi?id=918055