Closing a Stage from within its controller

In JavaFX 2.1, you have few choices. The way like in jewelsea's answer or the way what you have done already or modified version of it like

public class AboutBox extends Stage {

    public AboutBox() throws Exception {
        initModality(Modality.APPLICATION_MODAL);
        Button btn = new Button("Close");
        btn.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent arg0) {
                close();
            }
        });

        // Load content via
        // EITHER

        Parent root = FXMLLoader.load(getClass().getResource("AboutPage.fxml"));
        setScene(new Scene(VBoxBuilder.create().children(root, btn).build()));

        // OR

        Scene aboutScene = new Scene(VBoxBuilder.create().children(new Text("About me"), btn).alignment(Pos.CENTER).padding(new Insets(10)).build());
        setScene(aboutScene);

        // If your about page is not so complex. no need FXML so its Controller class too.
    }
}

with usage like

new AboutBox().show();

in menu item action event handler.

You can derive the stage to be closed from the event passed to the event handler.

new EventHandler<ActionEvent>() {
  @Override public void handle(ActionEvent actionEvent) {
    // take some action
    ...
    // close the dialog.
    Node  source = (Node)  actionEvent.getSource(); 
    Stage stage  = (Stage) source.getScene().getWindow();
    stage.close();
  }
}