function addEvent(elm, evType, fn {
        if (elm.addEventListener) {
                elm.addEventListener(evType, fn, false);
        return true;
        }
        else if (elm.attachEvent) {
                var r = elm.attachEvent('on' + evType, fn);
                return r;
        }
        else {
                elm['on' + evType] = fn;
        }
}