[code]
<style type="text/css">
.stext,
.sbox
{
    margin-left: 0;
    position: absolute;
    border: 1px solid black;
}

.stext
{
    width: 200px;
    z-index: 100;
    border-right: 0px solid black;
}

.sbox
{
    width: 218px;
}
</style>


<!--[if lt IE 7]>
    <style type="text/css">
    .sbox
    {
        width: 220px;
    }
</style>
<![endif]-->


<script type="text/javascript">
function stext(selectid, textid)
{
    var select = document.getElementById(selectid);
    var selectvalue = select.value;
    var text = document.getElementById(textid);
    text.value = selectvalue;
}
</script>


<!--[if ie]>
    <script type="text/javascript">
    function stext(selectid, textid)
    {
        var select = document.getElementById(selectid);
        var selectvalue = select.options[select.selectedIndex].value;
        var text = document.getElementById(textid);
        text.value = selectvalue;
    }
    </script>
<![endif]-->


<noscript>Voor deze functie is JavaScript nodig.</noscript>
<input type="text" id="text" class="stext">
<select onchange="stext('select', 'text')" id="select" class="sbox">
    <option value="Test">Test</option>
    <option value="Nog een Test">Nog een test</option>
</select>
[/code]