CONTENT_CHANGE_TYPE_PANE_DISAPPEARED
Change type for TYPE_WINDOW_STATE_CHANGED event: Can mean one of two slightly different things. The primary meaning is that the node has a pane title, and was removed from the node hierarchy. It can also be sent if the pane title is set to null
after it contained a title. No source will be returned if the node is no longer on the screen. To make the change more clear for the user, the first entry in getText can return the value that would have been returned by getSource().getPaneTitle()
.