Even though jQuery.event.fix copies over the "data" property from originalEvent, it is overridden by the handler's data property in jQuery.event.handle, even when the handler's data property is not defined.
I know of atleast one event which has the "data" property is used, and that is the "message" event generated by a postMessage [1]. A workaround is to use the originalEvent's data directly. Since i searched but couldn't find the issue mentioned before, i'm posting it. [1] https://developer.mozilla.org/en/DOM/window.postMessage#The_dispatched_event