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
*/
	public ISelection getSelection() {
		Control control = getControl();
		if (control == null || control.isDisposed()) {
			return StructuredSelection.EMPTY;
		}
		List list = getSelectionFromWidget();
		return new StructuredSelection(list, comparer);
	}
	/**
	 * Retrieves the selection, as a <code>List</code>, from the underlying
	 * widget.
	 * 
	 * @return the list of selected elements
	 */
	protected abstract List getSelectionFromWidget();
	/**
	 * Returns the sorted and filtered set of children of the given element. The
	 * resulting array must not be modified, as it may come directly from the
	 * model's internal state.
	 * 
	 * @param parent
	 *            the parent element
	 * @return a sorted and filtered array of child elements
	 */
	protected Object[] getSortedChildren(Object parent) {
		Object[] result = getFilteredChildren(parent);
		if (sorter != null) {
			
			result = (Object[]) result.clone();