desktopnova-tray software package provides tray icon for DesktopNova, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install desktopnova-tray
desktopnova-tray is installed in your system.
Make ensure the desktopnova-tray package were installed using the commands given below,
$ sudo dpkg-query -l | grep desktopnova-tray *
You will get with desktopnova-tray package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Miscellaneous |
| Package | desktopnova-tray |
| Version | 0.8.1-1+b1 [armhf], 0.8.1-1 [a |
| Description | tray icon for DesktopNova |
| Sub Section | Miscellaneous |