There is a contradition statement in the DOM L3 Events spec for keyboard events in the CompositionEvents section:
*** no keyboard events should generated:
While a composition session is active, keyboard events should not be dispatched to the DOM (i.e., the text composition system “swallows” the keyboard events), and only compositionupdate events are dispatched to indicate the composition process.
*** keydown event is generated:
When a keyboard is used to feed an input method editor, this event type is generated after a keydown event, but speech or handwriting recognition systems may send this event type without keyboard events.
We do have a public test case for the 2nd scenario -- compositionstart event type is generated after a keydown event:
Recommended fix is to correct the statement in http://www.w3.org/TR/DOM-Level-3-Events/#events-compositionevents to match implementations and eliminate this contradiction.
Now fixed in revision 1.214
As the opener, I verify that this has been fixed.