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.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentService.java
return resultInstances;
	}
	/**
	 * @return the viewer
	 */
	public Viewer getViewer() {
		return structuredViewerManager.getViewer();
	}
	
	/**
	 * Get our preferences
	 */
	static IEclipsePreferences getPreferencesRoot() {
		IEclipsePreferences root = (IEclipsePreferences) Platform.getPreferencesService().getRootNode().node(
				InstanceScope.SCOPE);
		return (IEclipsePreferences) root.node(NavigatorPlugin.PLUGIN_ID);
	}
	
	
	static void flushPreferences(IEclipsePreferences prefs) {
		try {
			prefs.flush();
		} catch (BackingStoreException e) {
			IStatus status = new Status(IStatus.ERROR, Platform.PI_RUNTIME, IStatus.ERROR,
					CommonNavigatorMessages.NavigatorContentService_problemSavingPreferences, e);
			Platform.getLog(Platform.getBundle(NavigatorPlugin.PLUGIN_ID)).log(status);
		}
	}
}