Tray Icon integration does not work.
From Question #194553:
I installed Nuvola and the app indicator appears in the notifications area, clicking on the volume indicator shows the Nuvola app, clicking on it brings up the google music web page but the arrow buttons "play, forward, reverse" do nothing and closing the browser window stops music from playing. I have no user scripts installed, I am using true Adobe Flash and it is up to date. Chromium is the web browser. Any suggestions? I tried reinstalling but no luck there either.