The menu does not even appear sometimes (just the LibreOffice text in upper left corner)
Going to launcher (Alt-WindowKey or Alt-Cmd) and selecting LibreOffice (calc in my case) reveals the menu.
However, they sometimes don't react to menu selection even though enabled.
Conclusion: There is something wrong with unity integration
The menu does not even appear sometimes (just the LibreOffice text in upper left corner)
Going to launcher (Alt-WindowKey or Alt-Cmd) and selecting LibreOffice (calc in my case) reveals the menu.
However, they sometimes don't react to menu selection even though enabled.
Conclusion: There is something wrong with unity integration