Combo selected item on the first of the list?

I am trying a combo with a long item list. After I select an item, I like this item stay on the top of the list. Is it easy to implement this function?

Thanks,

If you want to scroll the combo/list you have to do it via DOM API -

combo.showPopup1 = combo.showPopup;
combo.showPopup = function(){
    this.showPopup1(); 
    this.getViewTemplate().element().parentNode.scrollTop = 100; 
}