OBS + jitsi. How to share windows projector OBS

Hi evrybody
I would like to share a window with all my elements from OBS. But this window (not OBS but projector in window) doesn’t appear in sharing screen options.
I’m on Ubuntu 18.04.2 LTS
Jitsi is running on chromium or firefox
Thanks for help
Philj

Use a virtual camera plugin for OBS: https://blog.jbrains.ca/permalink/using-obs-studio-as-a-virtual-cam-on-linux
It worked well for me.
(it will hopefully soon be integrated in the obs release. Changes are merged in the repo but not yet in any released packages.)