Under Ubuntu 18.04.1 LTS
No menubar in libreoffice windows when libreoffice-gtk3 package is installed.
Menubar is present when libreoffice-gtk3 is suppressed.
Steps to Reproduce:
1.open or create an openoffice document
User Profile Reset: No
probably unity menu related
Is this with the Ubuntu packages or with the documentfoundation ones ? Is it a default Ubuntu gnome session ? or anything more exotic ?