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
if (data != element) {
			if (data != null) {
				disassociate(item);
			}
			item.setData(element);
			mapElement(element, item);
			if (associateListener != null)
				associateListener.associate(element, item);
		} else {
			
			
			
			mapElement(element, item);
		}
	}
	
	/**
	 * Disassociates the given SWT item from its corresponding element. Sets the
	 * item's data to <code>null</code> and removes the element from the
	 * element map (if enabled).
	 * 
	 * @param item
	 *            the widget
	 */
	protected void disassociate(Item item) {
		if (associateListener != null)
			associateListener.disassociate(item);
		Object element = item.getData();
		Assert.isNotNull(element);