How to enable KDE's Top Screen Menubar in non-qt programs?

I’ve enabled KDE’s Top Screen Menubar but it works only in qt programs. How could I enable it in Firefox, LibreOffice and normal GTK -programs? I’ve tried installing appmenu-gtk,-2 and -3, globalmenu-extension (for FF & LO), relog, but that doesn’t have an effect. I’m using KDE 4.11.1, openSUSE 12.3, FF 24.0, LO 4.0.

I know FF has extensions that hide the menu but I’m looking solutions that would unify the behaviour of programs.

Any solution in the meantime? I cannot use appmenu until it is compatible with Libreoffice