Metro UI FluentMenu

I want to populate a Metro UI FluentMenu dropdown (see class="fluent-big-button dropdown-toggle") from http://metroui.org.ua/fluent-menu.html via an AJAX servercall. But after inserting the received elements into the DOM the dropdown doesn't appear, but all the elements are correctly located in the DOM.

I think I need an additional initialization after loading the new elements but I have no idea how to do this.

After inspecting the library I saw, the fluentmenu is realized as jQuery-widget (https://learn.jquery.com/jquery-ui/widget-factory/how-to-use-the-widget-factory/) - can I "re-initialize" these plugins (the first time seems to be after the page load completion)?

Thanks with regards, Phil

The problem can be fixed by calling:

$("[data-role=dropdown]").dropdown();