Adds the listener to the collection of listeners who will
be notified when the menu item is selected by the user, by sending
it one of the messages defined in the <code>SelectionListener</code>
interface.
<p>
When <code>widgetSelected</code> is called, the stateMask field of the event object is valid.
<code>widgetDefaultSelected</code> is not called.
</p>
@param listener the listener which should be notified when the menu item is selected by the user
@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 menu item is selected by the user, by sending it one of the messages defined in the <code>SelectionListener</code> interface. <p> When <code>widgetSelected</code> is called, the stateMask field of the event object is valid. <code>widgetDefaultSelected</code> is not called. </p>
@param listener the listener which should be notified when the menu item is selected by the user
@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 SelectionListener @see #removeSelectionListener @see SelectionEvent