final DTCellValue52 defaultValue = ac.getDefaultValue();
final Integer numericValue = (Integer) defaultValue.getNumericValue();
tb.setValue( numericValue == null ? "" : numericValue.toString() );
tb.setEnabled( !isReadOnly );
if ( !isReadOnly ) {
tb.addValueChangeHandler( new ValueChangeHandler<String>() {
public void onValueChange( ValueChangeEvent<String> event ) {
DTCellValue52 clonedDefaultValue = defaultValue.cloneDefaultValueCell();
try {
defaultValue.setNumericValue( Integer.valueOf( event.getValue() ) );