int row = event.getFirstRow();
int column = event.getColumn();
if (column != TableModelEvent.ALL_COLUMNS && row == event.getLastRow()) {
// Get the value in the transformer's correspondence attribute.
TransformationRule transformer = (TransformationRule) getModel();
Pattern pattern = transformer.getPattern();
Replacement replacement = transformer.getReplacement();
String newValue = _getCellEditorValue((JPanel) _tableModel
.getValueAt(row, column));
String previousString = _cellEditor.getPreviousString();
if (previousString.equals(newValue)) {
return;