codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Untitled Page</title>

    <script language="javascript" type="text/javascript">
// <!CDATA[
    //------------------------------------------------------------
    //restituisce gli elementi value selezionati da una lista
    //separati da virgola
    //------------------------------------------------------------
    function options_value_selezionati_join(lista)
    {
	    var s = "";
	    for(var i = 0; i < lista.options.length; i++)
	    {
		    if(lista.options[i].selected) s += "," + lista.options[i].value;
	    }
	    return s.substr(1);
    }

function spedisci()
{
    var s = options_value_selezionati_join(document.FORM1.tec)
    + ";" + options_value_selezionati_join(document.FORM1.opr);
    alert(s);
    if(window.opener && window.opener.document.FORM1.tec) window.opener.document.FORM1.tec.value = s;   
    window.close();
}



// ]]>
</script>

</head>
<body>
    <form name="FORM1">
    <select size="15" name="tec" multiple>
        <option>Seleziona</option>
        <option value="GABRIELE">GABRIELE</option>
        <option value="GIUSEPPE">GIUSEPPE</option>
        <option value="DOMENICO">DOMENICO</option>
    </select>
    <select size="15" name="opr" multiple>
        <option>Seleziona</option>
        <option value="GIOVANNI">GIOVANNI</option>
        <option value="GIACOMO">GIACOMO</option>
        <option value="DOROTEO">DOROTEO</option>
    </select>
    </form>
    
    xxxxx
    
</body>
</html>