About system tray icons. In release-juno, elementaryOS dropped the support of the old Ayatana Indicators
While the software devs implement the new way you can have them back by...
$ sudo add-apt-repository ppa:yunnxx/elementary
$ sudo apt update
$ sudo apt install indicator-application wingpanel-indicator-ayatana
then you need to edit a file (i used nano, use any editor you want - avoiding a holy war)
$ sudo nano /etc/xdg/autostart/indicator-application.desktop
find the line
OnlyShowIn=Unity;GNOME;
and add Pantheon
OnlyShowIn=Unity;GNOME;Pantheon;
that's it, just restart X and you will have the old notification area icons
https://elementaryos.stackexchange.com/a/17453/14940