class MenuButton : Button {
    override fun onClicked( event : MouseEvent ) {
        // If we are play one of the scene in a "MORE" menu, then
        // return to that menu.
        // Otherwise, return to the main menu.
        val sceneName = Game.instance.sceneName
        if ( sceneName.contains("/") ) {
            val slash = sceneName.indexOf("/")
            val dir = sceneName.substring(0,slash)
            val menuName = "$dir/$dir"
            if (Game.instance.resources.sceneExists( menuName ) ) {
                Game.instance.startScene("$dir/$dir")
                return
            }
        }
        Game.instance.startScene("menu")
    }
}