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
* <p>
	 * Unlike the <code>update</code> methods, this handles structural changes
	 * to the given element (e.g. addition or removal of children). If only the
	 * given element needs updating, it is more efficient to use the
	 * <code>update</code> methods.
	 * </p>
	 * 
	 * @param element
	 *            the element
	 * @param updateLabels
	 *            <code>true</code> to update labels for existing elements,
	 *            <code>false</code> to only update labels as needed, assuming
	 *            that labels for existing elements are unchanged.
	 * 
	 * @since 2.0
	 */
	public void refresh(final Object element, final boolean updateLabels) {
		preservingSelection(new Runnable() {
			public void run() {
				internalRefresh(element, updateLabels);
			}
		});
	}
	/**
	 * 
	 * Refreshes the given item with the given element. Calls
	 * <code>doUpdateItem(..., false)</code>.
	 * <p>
	 * This method is internal to the framework; subclassers should not call
	 * this method.