Called whenever the items have changed in some way e.g. an item has been added or removed.
updateActiveItems
voidupdateActiveItems()
Called whenever the currently active items need to be re-rendered.
Note: Does not update the activation itself. For that purpose use updateActivation().
Called whenever the activation needs to be updated i.e. which items are currently rendered as "active".
Note: Does not re-render the items themselves, only the activation state of them. In order to update the
items use updateActiveItems().
updateSelection
voidupdateSelection()
Called whenever the selection is changed in some way and the view needs to update itself accordingly.