<html>
<body>
<form>
<select name="sel" id="selid" multiple>
<option value="1">Opcion1</option>
<option value="2" selected>Opcion2</option>
<option value="3">Opcion3</option>
<option value="4">Opcion4</option>
</select>
<input type="button" value="Mover" onclick="mover();">
</form>
<script type="text/javascript">
osel = document.getElementById("selid");
function mover(){
for(i=0; i < osel.options.length; i++)
if(osel.options[i].selected){
desseleccionar(i);
if(i == osel.options.length - 1)
osel.options[0].selected = true;
else
osel.options[i + 1].selected = true;
break;
}
}
function desseleccionar(idx){
osel.options[idx].selected = false;
}
</script>
</body>
</html>