public static void CloseUpdateChecker()
 {
     if (instance != null)
     {
         instance.Close();
         instance = null;
     }
 }
        public static void Show(
            string appName,
            Assembly targetAssembly,
            ReleaseNote releaseNote)
        {
            instance = new UpdateCheckerView();

            instance.Owner = WPFHelper.MainWindow;
            instance.ViewModel.AppName.Value        = appName;
            instance.ViewModel.TargetAssembly.Value = targetAssembly;
            instance.ViewModel.Model.Value          = releaseNote;

            instance.Show();
        }