void addEventListener(
    in DOMString type, 
    in EventListener listener, 
    in boolean useCapture); 

void close(); 

boolean dispatchEvent(
    in Event evt) raises(EventException); 

void postMessage(
    in DOMString message,
    in Array messagePorts) raises(DOMException); 

void removeEventListener(
    in DOMString type, 
    in EventListener listener, 
    in boolean useCapture); 

void start(); 

attribute EventListener onmessage;