private void WhenBoxLostFocus()
 {
     if (_PopupContent != null)
     {
         _PopupContent.IsOpen = false;
         OnAyBoxLostFocus?.Invoke(this, null);
     }
 }
        private void Btn_Click(object sender, RoutedEventArgs e)
        {
            Button btn = sender as Button;
            var    _1  = btn.Tag.ToString();

            Text = _1;
            _PopupContent.IsOpen = false;
            OnAyBoxLostFocus?.Invoke(this, null);
        }