Currently, the Screeners Browser includes ScreeningRoomUsers that do not
have the 'screener' role.  It was requested that non-screener users be
excluded from this search result.

In this case, we'll probably want to add a 'Users Browser' to allow
searching across all users, regardless of their role.  Alternately, we
could add a filterable column 'user roles', allowing the search result
to be customized by the user, and possibly have a default 'role contains
screener' criterion.