Found a new gem after installing a Chromecast HDMI puck on my AV receiver. Apparently, it allows to display the Roon play screen on the TV. Pretty cool feature. Now I can listen to my music in the TV room (have a decent setup there as well) and watch the Roon info.
That is the display icon, letting the user know an active display is available. It need not be a chromecast. It could have been a webpage that had loaded the web display page as well.
Took an older iPad and hooked it up as a Roon display in my living and it works as well as the Chromecast unit with the TV.