Bug 262706 [CommonNavigator] Sorter inconsistently uses possible children instead of trigger points
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonViewerSorter.java
* <b>org.eclipse.ui.navigator.navigatorContent/navigatorContent/commonSorter</b> elements
 * available in the set of <i>visible</i> content extensions.
 * 
 * <p>
 * The CommonViewerSorter must be assigned a {@link INavigatorContentService} to drive its sorting
 * algorithm. Without a vaild content service, the sorter will return the default ordering.
 * </p>
 * <p>
 * A CommonViewerSorter may not be attached to more than one CommonViewer.
 * </p>
 * 
 * <p>
 * Clients may not extend this class.
 * </p>
 * 
 * 
 * 
 * @since 3.2
 * 
 */
public final class CommonViewerSorter extends TreePathViewerSorter {
	
	private static final int LEFT_UNDERSTANDS = 1;
	private static final int RIGHT_UNDERSTANDS = 2; 
	private static final int BOTH_UNDERSTAND = LEFT_UNDERSTANDS | RIGHT_UNDERSTANDS; 
	private NavigatorContentService contentService;
	private INavigatorSorterService sorterService;
	/**
	 * Create a sorter service attached to the given content service.
	 *