HTML Form Combo Box

I found an interesting article on how to create a Combo Box in DHTML. Form controls are definitely in need of the combo box, but I’m not so sure this does the job all that well.
A combo box is a drop down select list that can also allow the user to input his or her own strings. The author of the article builds one in DHTML by first placing a select list on the page and then placing a textbox on top of it using CSS. He then causes the dropdown list to make a Javascript function call, causing the textbox to update with the value of the list’s selection. It’s interesting in concept, but you can tell something strange is happening. Looking at the page, you can tell there’s a rendering error (in this case not an error) and that there are controls stacked on top of each other.