This application finds windows using GTK GMenu DBus interfaces [1] and forwards them through DBusMenu. This way no adjustments in Plasma are needed.
TODO:
* Monitor menu and action changes and relay them appropriately
* Meddle with gtk3 ini or gconf to hide the menu bar of apps, set `gtk-shell-shows-app-menu`
[1] https://wiki.gnome.org/Projects/GLib/GApplication/DBusAPI#org.gtk.Menus