altre idee?

ho provato anche cosi

<script>
function CambiaDir(s) {
document.edit.textfield.value = window.document.edit.IDXSOTTOREPARTO.options[0].value;
}
</script>
<html>
<head>
<title>Untitled Document</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>

<body>
<form name="edit" method="post" action="<%=Gest_Page%>">
<select name="IDXSOTTOREPARTO" id="IDXSOTTOREPARTO" class="edit" style="">
<option value="4" vdir="SIGARI"> COIBA </option>
<option value="8" vdir="SIGARI" >CUBANI</option>
<option value="13" vdir="ACCENDINI" >ZIPPO</option>
</select>
...
<input type="text" name="textfield">
</form>
</body>
</html>