Bug 55592 [Contributions] SubActionBars does not properly handle menu listeners
bundles/org.eclipse.jface/src/org/eclipse/jface/action/SubContributionManager.java
* Method declared on IContributionManager.
	 */
	public boolean isDirty() {
		return parentMgr.isDirty();
	}
	/* (non-Javadoc)
	 * Method declared on IContributionManager.
	 */
	public boolean isEmpty() {
		return parentMgr.isEmpty();
	}
	/**
	 * Returns whether the contribution list is visible.
	 * If the visibility is <code>true</code> then each item within the manager 
	 * appears within the parent manager.  Otherwise, the items are not visible.
	 *
	 * @return <code>true</code> if the manager is visible
	 */
	public boolean isVisible() {
		return visible;
	}
	/**
	 * Notifies that an item has been added.
	 * <p>
	 * Subclasses are not expected to override this method.
	 * </p>
	 *
	 * @param item the item contributed by the client
	 * @param wrap the item contributed to the parent manager as a proxy for the item
	 *      contributed by the client