BindingManagerBase is an abstract class, so an derived implementation must
actually listen to the DataView.ListChanged events and translate those events
into a PositionChanged event. When the DataView.RowFilter is set, a
ListChanged event is fired with ListChangedType.Reset.
For example the CurrencyManager will fire a PositionChanged when and
individual element moves, but not on a reset; instead a
CurrencyManager.ItemChanged event is triggered.