Install indicator-applet by entering the following commands in the terminal:
sudo apt update sudo apt install indicator-applet
Description:
GNOME panel indicator applet
indicator-applet is an applet to display information from various applications consistently in the GNOME panel. . Currently this includes support for messaging applications in the indicator-messages package.
Homepage: https://launchpad.net/indicator-applet
Version: 12.10.2+17.10.20170425-0ubuntu1
Section: universe/gnome