java.lang.NullPointerException
        at com.sun.javafx.scene.control.skin.LabeledSkinBase.updateDisplayedText(LabeledSkinBase.java:384)
        at com.sun.javafx.scene.control.skin.LabeledSkinBase.layoutLabelInArea(LabeledSkinBase.java:941)
        at com.sun.javafx.scene.control.skin.LabeledSkinBase.layoutLabelInArea(LabeledSkinBase.java:866)
        at com.sun.javafx.scene.control.skin.LabeledSkinBase.layoutChildren(LabeledSkinBase.java:850)
        at javafx.scene.control.Control.layoutChildren(Control.java:481)
        at javafx.scene.Parent.layout(Parent.java:1012)
        at javafx.scene.Parent.layout(Parent.java:1020)
        at javafx.scene.Scene.layoutDirtyRoots(Scene.java:517)
        at javafx.scene.Scene.doLayoutPass(Scene.java:488)
        at javafx.scene.Scene.access$3900(Scene.java:172)
        at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2222)
        at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:346)
        at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:502)
        at com.sun.javafx.tk.quantum.QuantumToolkit$11.run(QuantumToolkit.java:355)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.access$100(Unknown Source)
        at com.sun.glass.ui.win.WinApplication$3$1.run(Unknown Source)
        at java.lang.Thread.run(Thread.java:662)


Sample to reproduce:

import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.CheckBox;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;


public class Main extends Application {

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

    VBox root = new VBox();

    @Override
    public void start(final Stage stage) throws Exception {
        Scene scene = new Scene(root, 300, 300);
        final Label label = new Label("_Label");
        Button button = new Button("Button");
        CheckBox check = new CheckBox("Parse mnemonics");
        check.selectedProperty().addListener(new ChangeListener<Boolean>() {
            public void changed(ObservableValue<? extends Boolean> ov, Boolean t, Boolean t1) {
                label.setMnemonicParsing(t1);
            }
        });
        root.getChildren().addAll(label, button, check);
        stage.setScene(scene);
        stage.show();
    }
}