Bug 249574 [Contributions] ExternalActionManager.addPropertyChangeListener() doesn't register the ListenerList
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ExternalActionManager.java
/**
		 * Allow the callback to filter out actions that should not fire
		 * execution events.
		 * 
		 * @param action
		 *            The action with an actionDefinitionId
		 * @return true if this action should be considered.
		 */
		public boolean isApplicable(IAction action);
	}
	
	/**
	 * <p>
	 * A callback for executing execution events. Allows
	 * <code>ActionContributionItems</code> to fire useful events.
	 * </p>
	 * <p>
	 * Clients must not implement this interface and must not extend.
	 * </p>
	 * 
	 * @since 3.4
	 * 
	 */
	public static interface IExecuteCallback {