One of the more interesting differences between Unity and other desktop environments is that Unity isn’t afraid to pursue unconventional features and changes that might alienate traditional Linux users.
And the global app menu is one of those features.
If you’ve ever used OS X, then you know that app menu options are displayed in the menu bar that runs along the top of the screen. Until Unity adopted a global app menu of its own, no other major OS used this kind of interface design.
Many non-Mac users despise the design, but there are some who prefer it, and maybe you’re in that group. Unfortunately, there are other quirks and issues with Unity that may keep you from using it. So if you want a global app menu, does that mean you’re out of luck?
First, open Terminal and install these modules:
sudo apt-get install unity-gtk2-module unity-gtk3-module
Next, download the global menu applet and extract it. You should see a folder named globalAppMenu@lestcape alongside a README.md and some other files.
Copy the @lestscape folder to this location:
Lastly, launch Cinnamon Settings and add the applet to one of your panels, most likely one that runs along the top of the screen. Log out, then log in, and you should now have menu options there according to the currently active app.