JaveFX toggle button doesn't return to default after setting background - javafx

Question

I have the following code in my app
private void showImg(ToggleButton tb) {
Image img = new Image(getAssociatedImage(tb), tb.getWidth(), tb.getHeight(), false, true, true);
BackgroundImage bimg = new BackgroundImage(img, BackgroundRepeat.NO_REPEAT, BackgroundRepeat.NO_REPEAT, BackgroundPosition.CENTER, new BackgroundSize(tb.getWidth(), tb.getHeight(), true, true, true, false));
Background bkg = new Background(bimg);
Background old = tb.getBackground();
tb.setBackground(bkg);
PauseTransition pause = new PauseTransition(Duration.seconds(3));
pause.setOnFinished(event -> {
tb.setBackground(old);
});
pause.play().
}
It mainly does as I've expected, showing the new background img for 3 seconds, but after "restoring" the old background the ToggleButton looks and feel different; It doesn't look "metalic" as it used to, clicking on it doesn't make it appear "selected", no hovering reaction.
I'm not sure what I've done wrong here I returned the original background of the button and expected it to go back to "default"
EDIT:
minimal working example
public class Test2 extends Application{
#Override
public void start(Stage stage) throws Exception {
ToggleButton root = new ToggleButton();
root.setPrefHeight(300);
root.setPrefWidth(300);
root.setOnAction(event -> {
Image img = new Image(getClass().getResource("1.png").toExternalForm(), root.getWidth(), root.getHeight(), false, true, true);
BackgroundImage bimg = new BackgroundImage(img, BackgroundRepeat.NO_REPEAT, BackgroundRepeat.NO_REPEAT, BackgroundPosition.CENTER, new BackgroundSize(root.getWidth(), root.getHeight(), false, false, true, false));
Background bkg = new Background(bimg);
Background old = root.getBackground();
root.setBackground(bkg);
PauseTransition pause = new PauseTransition(Duration.seconds(3));
pause.setOnFinished(evt -> {
root.setBackground(old);
});
pause.play();
});
Scene scene = new Scene((Parent)root);
stage.setTitle("Example");
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}