question: public void propertyChange ( PropertyChangeEvent e ) { String propertyName = e . getPropertyName ( ) ; if ( propertyName == "visible" ) { if ( e . getOldValue ( ) == Boolean . FALSE && e . getNewValue ( ) == Boolean . TRUE ) { handlePopupIsVisibleEvent ( true ) ; } else if ( e . getOldValue ( ) == Boolean . TRUE && e . getNewValue ( ) == Boolean . FALSE ) { handlePopupIsVisibleEvent ( false ) ; } } }
target:  This method gets called when a bound property is changed.