This method handles WM_CHAR messages.
HRESULT KeyPress( long lKeyDown );
NOERROR indicates that the control handled the message. S_FALSE indicates that the control did not handle the message. If an error occurs, the appropriate HRESULT value is returned.
If a message sink exists, the control forwards the message to the IASClassMsgSink::KeyPress method.
IASClassMsgSink::HandleKeyPress