The specification for method

http://download.java.net/jdk8/docs/api/javax/swing/event/AncestorListener.html#ancestorRemoved(javax.swing.event.AncestorEvent)

contains a typo. See "...being remove from..." in following sentence - 'd' is missed.

"Called when the source or one of its ancestors is made invisible either by setVisible(false) being called or by its being remove from the component hierarchy."