I am trying to set keyCode on dispatched event object .
On button click, event is raised on textbox control to simulating keydown event. Event is raised successfully
It is not a bug... this feature is being weeded out, deprecated, forbidden, whateva' the name will be tomorrow... You cannot rely on this feature to work for long. ...and is a wide open security risk... find another way to do what you are trying to do. Consult the MOZILLA specs and you will see the BIG BAD RED BANNER which warns to avoid this like the plague. They will not fix it, by returning 0 they effectively stop the bleeding without changing the code except in one place where it always zaps the keyCode to 0.