private void CopyMenuItem_Click(object sender, RoutedEventArgs e)
        {
            var responses = (DataContext as QueryWindowVM).Responses;

            if (responses != null)
            {
                string html     = HtmlUtils.EnumerableToHtmlTable(responses, r => r.Response, r => r.User, r => r.Timestamp);
                string fileName = System.IO.Path.GetTempPath() + Guid.NewGuid().ToString() + ".xls";
                try
                {
                    File.WriteAllText(fileName, html);
                    Process.Start(fileName);
                }
                catch (Exception ex)
                {
                    AppErrorBox.ShowErrorMessage("Error while generating excel . .", ex.ToString());
                }
            }
        }