Ubuntu 16.04 menus are always displayed

I recently upgraded from 14.04 to 16.04 LTS, and although the system works properly and is generally stable, there is an issue that bugs me.

For the windows that have a menu bar, it is always displayed, regardless of the value selected in the "menus visibility" setting. See figures below:

On a different system that I also upgraded, the menu is hidden properly when the setting is selected.

What can cause this behavior? Is there anything that I can do to fix it?

I tried resetting my unity settings with unity --reset, with sudo apt install --reinstall ubuntu-desktop and with sudo apt install --reinstall unity with no luck.

The result of the dpkg -l indicator-appmenu command is:

$ dpkg -l indicator-appmenu
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name           Version      Architecture Description
+++-==============-============-============-=================================
rc  indicator-appm 13.01.0+14.0 amd64        Indicator for application menus.

Your system is missing the indicator-appmenu package. Without that package you won't get the application menu on the titlebar in Unity session.

And reinstalling ubuntu-desktop package wasn't fixing the problem because for some unknown reason, this package wasn't included in the dependency list of ubuntu-desktop package for 16.04 (You can check it by using apt-cache depends ubuntu-desktop command).

So, to fix the issue, install the package with this command

sudo apt-get install indicator-appmenu