void yesConfirm(object s, DialogClickEventArgs e)
    {
      Toast.MakeText(this, "Confirmed to proceed!", ToastLength.Short).Show();
    }

    void noConfirm(object s, DialogClickEventArgs e)
    {
      Toast.MakeText(this, "Cancelled!", ToastLength.Short).Show();
    }


    void btnAllow_Click(object sender, EventArgs e)
    {
      AlertDialog.Builder builder = new AlertDialog.Builder(this);

      builder.SetMessage("Are you sure?");
      builder.SetCancelable(false);

      builder.SetPositiveButton("yes", yesConfirm);
      builder.SetNegativeButton("no", noConfirm);

      AlertDialog alert = builder.Create();
      alert.Show();