This is about the right-hand column you see when looking at an actual conversation in Conpherence (say Z1). Looking through the code, I think the term for this is the aptly-named widget.
Participants is the first choice and probably the most useful default as well. It looks like somebody even attempts to set it as the default at `src/applications/conpherence/controller/ConpherenceWidgetController.php:77`
Right now, it just takes up a lot of space and is useless. Alternatively, even hiding it would be good.