I tested this code with toggle buttons:

import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.geometry.Insets;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Toggle;
import javafx.scene.control.ToggleButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class Test extends Application
{
    @Override
    public void start(Stage primaryStage)
    {
        final VBox vbox = new VBox();
// String pillButtonCss = DX57DC.class.getResource("PillButton.css").toExternalForm();
        // create 3 toggle buttons and a toogle group for them
        ToggleButton tb1 = new ToggleButton("Left Button");
        tb1.setId("pill-left");
        ToggleButton tb2 = new ToggleButton("Center Button");
        tb2.setId("pill-center");
        ToggleButton tb3 = new ToggleButton("Right Button");
        tb3.setId("pill-right");
        final ToggleGroup group = new ToggleGroup();
        tb1.setToggleGroup(group);
        tb2.setToggleGroup(group);
        tb3.setToggleGroup(group);
        // select the first button to start with
        group.selectToggle(tb1);
        final Rectangle rect1 = new Rectangle(300, 300);
        rect1.setFill(Color.DARKOLIVEGREEN);
        final Rectangle rect2 = new Rectangle(300, 300);
        rect2.setFill(Color.LAVENDER);
        final Rectangle rect3 = new Rectangle(300, 300);
        rect3.setFill(Color.LIGHTSLATEGREY);
        tb1.setUserData(rect1);
        tb2.setUserData(rect2);
        tb3.setUserData(rect3);
        group.selectedToggleProperty().addListener(new ChangeListener<Toggle>()
        {
            @Override
            public void changed(ObservableValue<? extends Toggle> ov, Toggle toggle, Toggle new_toggle)
            {
                if (new_toggle == null)
                {
                }
                else
                {
                    vbox.getChildren().set(1, (Node) group.getSelectedToggle().getUserData());
                }
            }
        });
        HBox hBox = new HBox();
        hBox.getChildren().addAll(tb1, tb2, tb3);
        hBox.setPadding(new Insets(10, 10, 10, 10));
// hBox.getStylesheets().add(pillButtonCss);
        vbox.getChildren().addAll(hBox, (Node) group.getSelectedToggle().getUserData());
        StackPane root = new StackPane();
        root.getChildren().add(vbox);
        Scene scene = new Scene(root, 800, 850);
        primaryStage.setScene(scene);
        primaryStage.show();
    }
    public static void main(String[] args)
    {
        launch(args);
    }
}

When I press the Caps Lock I cannot switch the buttons. The Buttons are "locked". Is this a JavaFX bug or I have somewhere bug into my code?