private void btn1_Click(object sender, RoutedEventArgs e)
 {
     Manipulate.Add();
 }
 private void btn_Add(object sender, RoutedEventArgs e)
 {
     Manipulate.Add(this);
 }
 private void btn1_Click(object sender, RoutedEventArgs e)
 {
     MessageBox.Show("Added value= " + Manipulate.Add(this.BoxA, this.BoxB));
 }