object GUI {
    val listeners = mutableMapOf<String, (dynamic) -> Unit>()
    var connected by Delegates.observable(false) { prop, old, new ->
        listeners[prop.name]?.invoke(new)
    }

    @JsName("addListener")
    fun addListener(prop: dynamic, listener: (dynamic) -> Unit) {
        listeners[prop as String] = listener
    }

    @JsName("removeListener")
    fun removeListener(prop: dynamic) {
        listeners.remove(prop as String)
    }
}