https://www.reddit.com/r/discordapp/comments/9aiq3r/system_tray_issues_on_ubuntu_18041_lts/
Run /usr/bin/env XDG_CURRENT_DESKTOP=Unity before launching the App. Most Electron apps have this problem.
To edit the menu - https://imgur.com/9j5POtJ
Sadly does nothing for Pidgin or Mumble :/