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
* This should be called when an element has changed in the model, in order
	 * to have the viewer accurately reflect the model. This method only affects
	 * the viewer, not the model.
	 * </p>
	 * <p>
	 * Specifying which properties are affected may allow the viewer to optimize
	 * the update. For example, if the label provider is not affected by changes
	 * to any of these properties, an update may not actually be required.
	 * Specifying <code>properties</code> as <code>null</code> forces a full
	 * update of the given elements.
	 * </p>
	 * <p>
	 * If the viewer has a sorter which is affected by a change to one of the
	 * properties, the elements' positions are updated to maintain the sort
	 * order. Note that resorting may not happen if <code>properties</code>
	 * is <code>null</code>.
	 * </p>
	 * <p>
	 * If the viewer has a filter which is affected by a change to one of the
	 * properties, elements may appear or disappear if the change affects
	 * whether or not they are filtered out. Note that resorting may not happen
	 * if <code>properties</code> is <code>null</code>.
	 * </p>
	 * 
	 * @param elements
	 *            the elements
	 * @param properties
	 *            the properties that have changed, or <code>null</code> to
	 *            indicate unknown
	 */