così funziona su FF2.0 e IE6.0

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>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>...</title>
<script type="text/javascript">
function inizia()
{
    var paperino = document.getElementById( "paperino" );
    var pluto = document.getElementById("pluto");
    var form = document.createElement( "form" );    
    form.name = "modulo";
    form.action = "";
    var input = document.createElement("input");
    input.type = "text";
    input.name = "campo";
    input.id = "pippo";        
    input.value = "";
    if (window.XMLHttpRequest) {
        input.setAttribute( "onblur", "test_alert()" );
    } else {
        input.setAttribute( "onblur", function(){test_alert()}, true );
    }
    form.appendChild(input);
    paperino.appendChild(form);
    document.getElementById("pippo").focus();
}
function test_alert(){ alert('pippo'); }
</script>
</head>
<body onload="inizia()">
<div id="paperino"></div>

</body>
</html>