Global Menu is the globally-shared menu bar of all applications launched in your desktop session. (A replacement of the old Mac-Menu package) This project introduces document-oriented concepts into GNOME, and improves GNOME's respect for Fitts's law. Most GTK applications work just fine with Global Menu.

It replaces Mac Menubar for GNOME and Xfce listed at

http://www.gnomefiles.org/app.php/Mac_Menubar_for_GNOME_and_Xfce