private async void btnRefreshProgress_Click(object sender, EventArgs e)
        {
            try
            {
                var step     = (dgvSteps.DataSource as BindingSource).Current as DataMigration.Step;
                var progress = await _migrator.QueryMappingProgressAsync(_doc.Document, step);

                propertyGrid1.SelectedObject = progress;
            }
            catch (Exception exc)
            {
                MessageBox.Show(exc.Message);
            }
        }