This widget uses javascript to transform this:

Into this:

I.e.: A combination of text- and selectbox. You can type in a value or choose from the list

The only thing you have to do to make this work is to add an attribute "selectBoxOptions" to one of your text inputs:

<input type="text" name="myText" value="Norway" selectBoxOptions="Canada;Denmark;Finland;Germany;Mexico;Norway;Sweden;United Kingdom;United States">

And then simply call a javascript function that creates the editable select box:

<script type="text/javascript">
createEditableSelect(document.forms[0].myText);
</script>