Adds the listener to the collection of listeners who will
be notified when the help events are generated for the control, by sending
it one of the messages defined in the <code>HelpListener</code>
interface.
@param listener the listener which should be notified
@exception IllegalArgumentException <ul>
<li>ERROR_NULL_ARGUMENT - if the listener is null</li>
</ul>
@exception SWTException <ul>
<li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
<li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
</ul>
Adds the listener to the collection of listeners who will be notified when the help events are generated for the control, by sending it one of the messages defined in the <code>HelpListener</code> interface.
@param listener the listener which should be notified
@exception IllegalArgumentException <ul> <li>ERROR_NULL_ARGUMENT - if the listener is null</li> </ul> @exception SWTException <ul> <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> </ul>
@see HelpListener @see #removeHelpListener