Is it possible to change css for a JavaFX application while it is running?

The effect I am looking for is changing skins or themes at the click of a button.

The UI is in an FXML file if that makes any difference.

I have tried

Scene.getStylesheets()
  .add(getClass().getResource(skinFileName).toExternalForm());

which has no effect.

thanks

css javafx-2 javafx fxml
Edit
Report