if ( !isReadOnly() ) {
cwo.addValueChangeHandler( new ValueChangeHandler<OperatorSelection>() {
public void onValueChange( ValueChangeEvent<OperatorSelection> event ) {
setModified( true );
OperatorSelection selection = event.getValue();
String selected = selection.getValue();
c.getWindow().setOperator( selected );
getModeller().makeDirty();
}
} );
}