Bug 299438 [CommonNavigator] CNF viewer state non properly reset when NCEs are activated or deactivated
The map of the objects to the NCEs should be reset whenever the NCEs associated with the viewer to change to avoid having stale label information. This has shown up when looking at the CNF tests that change the viewer.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
sorter.sort(this, result);
		}
		return result;
	}
	/**
	 * Returns this viewer's sorter, or <code>null</code> if it does not have
	 * one.  If this viewer has a comparator that was set via 
	 * <code>setComparator(ViewerComparator)</code> then this method will return 
	 * <code>null</code> if the comparator is not an instance of ViewerSorter.
     * <p>
     * It is recommended to use <code>getComparator()</code> instead.
     * </p>
	 * 
	 * @return a viewer sorter, or <code>null</code> if none or if the comparator is 
	 * 				not an instance of ViewerSorter
	 */
	public ViewerSorter getSorter() {
		if (sorter instanceof ViewerSorter)
			return (ViewerSorter)sorter;
		return null;
	}
	/**
	 * Return this viewer's comparator used to sort elements.
	 * This method should be used instead of <code>getSorter()</code>.
	 * 
	 * @return a viewer comparator, or <code>null</code> if none
     *
	 * @since 3.2
	 */
	public ViewerComparator getComparator(){