By default, InteractorGroups are prioritized in list-order (first = highest priority).

An <cref="ICandidateComparer" /> can prioritize <cref="IInteractor" />s in a different order based on their CandidateProperties. For instance, for those IInteractors whose CandidateProperties can be cast to an ICandidatePosition, a CandidatePositionComparer can prioritize IInteractors by their candidates’ position as measured by a distance to a common location.