WinForm Display Busy Form after OnClick

internal static class DialogExt
{
  public static async Task<DialogResult> ShowDialogAsync(this Form @this, Form parent)
  {
    await Task.Yield(); //force it to be async
    if (@this.IsDisposed)
      return DialogResult.OK;
    return @this.ShowDialog(parent); //this will run on the UI thread at some point later
  }
}

/// <summary>
/// Use the 'async' keyword
/// </summary>
private async void sendAsyncBf_Click(object sender, EventArgs e)
{
  try
  {
    Result result = null;
    using (var bf = new BusyForm())
    {
      var showBusyFormTask = bf.ShowDialogAsync(this);
      result = await DoJobAsync();
      bf.Close();
      await showBusyFormTask;
    }
    log(JsonConvert.SerializeObject(result, Formatting.Indented));
  }
  catch (Exception ex)
  {
    log(ex.ToString());
  }
}

/// <summary>
/// Without the 'async' keyword
/// </summary>
private void sendAsyncBf2_Click(object sender, EventArgs e)
{
  try
  {
    using (var busyForm = new BusyForm())
    {
      busyForm.Shown += async (sd, args) =>
      {
        try
        {
          var result = await DoJobAsync();
          log(JsonConvert.SerializeObject(result, Formatting.Indented));
        }
        catch (Exception ex)
        {
          log(ex.ToString());
        }
        finally
        {
          busyForm.Close();
        }
      };
      busyForm.ShowDialog(this);
    }
  }
  catch (Exception ex)
  {
    log(ex.ToString());
  }
}