/// <summary>
 /// コンストラクタ
 /// </summary>
 /// <param name="cultureInfo">言語情報</param>
 public LangMenuItem(CultureInfo cultureInfo, bool isChecked)
 {
     CultureInfo = cultureInfo;
     IsChecked   = new ReactivePropertySlim <bool>(isChecked);
     IsCheckable = IsChecked.Inverse().ToReadOnlyReactivePropertySlim();
 }