Implemented by all controls/classes that are interested in knowing when the
RowSetIterator for an iteratorBinding in a panel is changed. Typically controls
like JUNavigationBar and JUStatusBar that are interested in updating their display
based on current iterator settings listen into this event (generated by JUPanelBinding).
When an iterator binding's iterator is changed via JUPanelBinding.bindRowSetIterator(),
PanelBinding notifies all such listeners of the change.
Note that if the iterator behind an IteratorBinding is changed via JUIteratorBinding.bindRowSetIterator(),
then it is left to the caller to perform this notification using a protected method in