private string _savePath = "";
    private void WebView_FileDialog(object sender, FileDialogEventArgs e)
    {
      if (_savePath == "")
      {
        if (e.Mode == FileDialogMode.Save)
        {
          var dialog = new Microsoft.Win32.SaveFileDialog();
          dialog.InitialDirectory = e.DefaultFileName;
          dialog.Title = "Select a Directory"; // instead of default "Save As"
          dialog.Filter = "Directory|*.this.directory"; // Prevents displaying files
          dialog.FileName = "select"; // Filename will then be "select.this.directory"
          if (dialog.ShowDialog() == true)
          {
            string path = dialog.FileName;
            // Remove fake filename from resulting path
            path = path.Replace("\\select.this.directory", "");
            path = path.Replace(".this.directory", "");
            // If user has changed the filename, create the new directory
            if (!System.IO.Directory.Exists(path))
            {
              System.IO.Directory.CreateDirectory(path);
            }
            // Our final value is in path
            _savePath = path;
            // go ahead and download the current file 
            e.Continue(System.IO.Path.Combine(path, System.IO.Path.GetFileName(e.DefaultFileName)));
            e.Handled = true;
          }
        }
      }
    }

    private void WebView_BeforeDownload(object sender, BeforeDownloadEventArgs e)
    {
      // https://www.essentialobjects.com/doc/eo.webbrowser.webview.beforedownload.aspx
      if (_savePath != "")
      {
        e.FilePath = System.IO.Path.Combine(_savePath, System.IO.Path.GetFileName(e.FilePath));
        e.ShowDialog = false;
      }
    }