Bug 249574 [Contributions] ExternalActionManager.addPropertyChangeListener() doesn't register the ListenerList
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ExternalActionManager.java
* Fires an execution event before an action is run.
		 * 
		 * @param action
		 *            The action contribution that requires an
		 *            execution event to be fired. Cannot be <code>null</code>.
		 * @param e
		 *            The SWT Event, may be <code>null</code>.
		 * 
		 */
		public void preExecute(IAction action,
				Event e);
		
		/**
		 * Fires an execution event when the action returned a success.
		 * 
		 * @param action
		 *            The action contribution that requires an
		 *            execution event to be fired. Cannot be <code>null</code>.
		 * @param returnValue
		 *            The command's result, may be <code>null</code>.
		 * 
		 */
		public void postExecuteSuccess(IAction action,
				Object returnValue);
		
		/**
		 * Creates an <code>ExecutionException</code> when the action returned
		 * a failure.
		 * 
		 * @param action