Causes the user-interface thread to
sleep (that is, to be put in a state where it does not consume CPU cycles) until an event is received or it is otherwise awakened.
@return
true
if an event requiring dispatching was placed on the queue.
@exception SWTException
- ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
@see #wake