Install gtrayicon by entering the following commands in the terminal:
sudo apt update sudo apt install gtrayicon
Description:
Generic tray icon for GNOME
Generic tray icon for GNOME is a small utility which allows to add a icon to the system tray that can be used to trigger customized enable/disable actions.
Homepage: http://gtrayicon.sourceforge.net/
Version: 1.1-1build1
Section: universe/utils