private void AddRow(object sender, MouseButtonEventArgs e)
{
DataGrid1.CancelEdit();
DataGrid1.SelectedIndex = -1;
DataGrid1.ItemsSource = null;
DataGrid1.CanUserSortColumns = false;
DataGrid1.ItemsSource = workers;
DataGrid1.CanUserAddRows = true;
DataGrid1.Columns[1].IsReadOnly = false;
DataGrid1.Columns[2].IsReadOnly = false;
DataGrid1.Columns[2].Visibility = Visibility.Visible;
DataGrid1.Columns[4].Visibility = Visibility.Hidden;
}