internal Selector(SelectorChangedCallback <T> cb, Selector <T> value) : this(value) { callback = cb; }
internal ColorSelector(SelectorChangedCallback <Color> cb, Selector <Color> selector) : base(cb, selector) { }
internal Selector(SelectorChangedCallback <T> cb) : this() { callback = cb; }
internal ColorSelector(SelectorChangedCallback <Color> cb) : base(cb) { }