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
* 
	 * @param x
	 *            horizontal coordinate
	 * @param y
	 *            vertical coordinate
	 * @return the item, or <code>null</code> if there is no item at the given
	 *         coordinates
	 * @deprecated This method is deprecated in 3.3 in favor of {@link ColumnViewer#getItemAt(org.eclipse.swt.graphics.Point)}. 
	 * Viewers who are not subclasses of {@link ColumnViewer} should consider using a
	 * widget relative implementation like {@link ColumnViewer#getItemAt(org.eclipse.swt.graphics.Point)}.
	 *  
	 */
	protected Item getItem(int x, int y) {
		return null;
	}
	
	/**
	 * Returns the children of the given parent without sorting and filtering
	 * them. The resulting array must not be modified, as it may come directly
	 * from the model's internal state.
	 * <p>
	 * Returns an empty array if the given parent is <code>null</code>.
	 * </p>
	 * 
	 * @param parent
	 *            the parent element
	 * @return the child elements
	 */
	protected Object[] getRawChildren(Object parent) {
		Object[] result = null;