Function actor_text_range 

pub fn actor_text_range<'p>(
    presence: &'p PresenceCtx,
    actor: &str,
) -> Option<(&'p PresenceKey, SelectionRange)>

The caret or selection presence holds for actor, with the key it is shown at: where that member says it is in text here. A member has at most one of the two, whichever it said last.