ListGrid edit a new row only

In the sample code provided by show case (http://www.smartclient.com/smartgwt/showcase/#grid_editing_new_row), when you click “Edit New”, you can edit the new added row. You can also click other rows above this new-added row to edit them. My question is “Can we only make the new-added row editable, not any other row?”. Thanks a lot.