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
* a different strategy for picking a new selection when the old selection
	 * becomes invalid.
	 * </p>
	 * 
	 * @param invalidSelection
	 *            the selection before the viewer was updated
	 * @param newSelection
	 *            the selection after the update, or <code>null</code> if none
	 */
	protected void handleInvalidSelection(ISelection invalidSelection, ISelection newSelection) {
		updateSelection(newSelection);
		SelectionChangedEvent event = new SelectionChangedEvent(this, newSelection);
		firePostSelectionChanged(event);
	}
	/**
	 * The <code>StructuredViewer</code> implementation of this
	 * <code>ContentViewer</code> method calls <code>update</code> if the
	 * event specifies that the label of a given element has changed, otherwise
	 * it calls super. Subclasses may reimplement or extend.
	 * </p>
	 * @param event the event that generated this update
	 */
	protected void handleLabelProviderChanged(LabelProviderChangedEvent event) {
		Object[] elements = event.getElements();
		if (elements != null) {
			update(elements, null);
		} else {
			super.handleLabelProviderChanged(event);
		}
	}