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 map from the viewer's model elements to SWT widgets. (key type:
	 * <code>Object</code>, value type: <code>Widget</code>, or <code>Widget[]</code>).
	 * <code>null</code> means that the element map is disabled.
	 */
	private CustomHashtable elementMap;
	/**
	 * The comparer to use for comparing elements, or <code>null</code> to use
	 * the default <code>equals</code> and <code>hashCode</code> methods on
	 * the element itself.
	 */
	private IElementComparer comparer;
	/**
	 * This viewer's comparator used for sorting. <code>null</code> means there is no comparator.