Another way to do this is (for selected apps) drawing the titlebar over the application menu:
This doesn’t require dbus menu. If your app has a menubar on top, which has space on the right side, you can turn on the overlay.
And it makes clear cut between the application part and the window decoration part of the title bar, which solves one of Nate Graham’s complaints on CSD.
The downside is now you can only place windows buttons on the right side.