Install classicmenu-indicator by entering the following commands in the terminal:
sudo apt update sudo apt install classicmenu-indicator
Description:
indicator showing the main menu from Gnome Classic
classicmenu-indicator displays the main menu from Gnome2/Gnome Classic
Homepage: http://www.florian-diesch.de/software/classicmenu-indicator/
Version: 0.10.1-0ubuntu1
Section: universe/gnome