function listen(evnt, elem, func) 
{
    if (elem.addEventListener) // W3C DOM
        elem.addEventListener(evnt,func,false);

    else if (elem.attachEvent) 
    { // IE DOM
        var r = elem.attachEvent("on"+evnt, func);
        return r;
    }
    else 
        window.alert('I\'m sorry Dave, I\'m afraid I can\'t do that.');
}