JavaFX, simple TreeView

NetBeans 7.4
New Project >> JavaFX >> JavaFX Application
We have one button and one label. When click button, label shows “Hello World!”
Based on sample code from
http://docs.oracle.com/javafx/2/api/javafx/scene/control/TreeView.html

Put them under
@FXML private void handleButtonAction(ActionEvent event)
, and modify some,

SimpleTreeView