write a beforeunload event in proprietaryEvent.js
write a mousewheel event in proprietaryEvent.js
mousewheel support Opera9.5- in proprietaryEvent.js
write a DOMMouseScroll event in proprietaryEvent.js
write getWheelDelta() in eventUtil.js
write getWheelDelta() in eventUtil.js
write a Usage of getWheelDelta in eventUtil.js