}
// Wire up update handler
lb.setEnabled( !isReadOnly );
if ( !isReadOnly ) {
lb.addClickHandler( new ClickHandler() {
public void onClick( ClickEvent event ) {
final String txtValue = lb.getValue( lb.getSelectedIndex() );
Boolean boolValue = ( txtValue.equals( "" ) ? null : txtValue.equals( "true" ) );
value.setBooleanValue( boolValue );