var browserHandler;
    if (element.addEventListener) {
        browserHandler = function (e) {
            return handler.call(element, new Sys.UI.DomEvent(e));
        };
        element.addEventListener(eventName, browserHandler, false);
    } else if (element.attachEvent) {
        browserHandler = function () {
            var e = {}; //Message: browserHandler is undefined
            try  {
                e = Sys.UI.DomElement._getWindow(element).event;
            } catch (ex) {
            }
            return handler.call(element, new Sys.UI.DomEvent(e));
        };
        element.attachEvent('on' + eventName, browserHandler);
    }