The blur() method of the Select object removes focus from the select box.
<html>
<head>
<script language="JavaScript">
<!--
function removeFocus(){
document.myForm.mySelect.blur();
}
-->
</script>
</head>
<body>
<P>
<form name="myForm">
<select name="mySelect" multiple>
<option value=A>AA</option>
<option value=B>BB</option>
<option value=C>CC</option>
<option value=D>DD</option>
</select>
<input type=BUTTON value="Click to Remove Focus" name="myButton"
onClick="removeFocus()">
</form>
</body>
</html>