I have created an empty list with the "disabledIfEmpty" option to true. Then i append some options in the list and rebuild it as in this example:

$.each(data, function (i, item) {
   selectControl.append('<option value="' + item.value + '" parentKey="' + item.parentKey + '">' + item.label + '</option>');
});
selectControl.multiselect('rebuild');

but the list stay disabled. Am i doing it wrong or is this a bug?
If it is really a bug see pull request: #495