How to listen for WindowEvent.WINDOW_SHOWN in the nodes of the scene graph?

It seems WindowEvent.WINDOW_SHOWN never gets dispatched on any of the nodes in the scene graph, nor is there anyway (that I could find) to know when a node is visible/rendered/shown. For example:

TestLauncher.java

package com.example.javafx.event;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class TestLauncher extends Application
{
    public static void main(String[] args)
    {
        Application.launch(TestLauncher.class, args);
    }

    @Override
    public void start(Stage stage) throws Exception
    {
        Parent root = FXMLLoader.load(TestController.class.getResource("TestView.fxml"));
        Scene scene = new Scene(root);
        stage.setScene(scene);
        stage.show();
    }
}

TestController.java

package com.example.javafx.event;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.Parent;
import javafx.scene.control.TextField;
import javafx.stage.WindowEvent;

public class TestController implements Initializable
{
    @FXML private Parent root;
    @FXML private TextField serverAddressInput;
    @FXML private TextField usernameInput;

    @Override
    public void initialize(URL url, ResourceBundle rb)
    {
        serverAddressInput.setText("127.0.0.1");

        //won't work because stage isn't visible yet
        trySetFocusOnUsernameInput1();

        //apparently Stage never passes on any WindowEvents to the children...
        trySetFocusOnUsernameInput2();
    }

    private void trySetFocusOnUsernameInput1()
    {
        usernameInput.requestFocus();
    }

    private void trySetFocusOnUsernameInput2()
    {
        root.addEventFilter(WindowEvent.WINDOW_SHOWN, new EventHandler<WindowEvent>()
        {
            @Override