鼠标滚轮事件（mousewheel、DOMMouseScroll）

(function() {
    function handleMouseWheel(event) {
        event = EventUtil.getEvent(event);
        var delta = EventUtil.getWheelDelta(event);
        console.log(delta);
    }

    EventUtil.addHandler(document, "mousewheel", handleMouseWheel);
    EventUtil.addHandler(document, "DOMMouseScroll", handleMouseWheel);
})();