Bug 262706 [CommonNavigator] Sorter inconsistently uses possible children instead of trigger points
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonViewerSorter.java
* @param aContentService
	 *            The content service used by the viewer that will use this sorter service.
	 * @since 3.3
	 */
	public void setContentService(INavigatorContentService aContentService) {
		contentService = (NavigatorContentService) aContentService;
		sorterService = contentService.getSorterService();
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.ViewerSorter#category(java.lang.Object)
	 */
	public int category(Object element) {
		if (contentService == null)
			return 0;
		INavigatorContentDescriptor source = getSource(element);
		return source != null ? source.getPriority() : Priority.NORMAL_PRIORITY_VALUE;
	}
	public int compare(Viewer viewer, TreePath parentPath, Object e1, Object e2) {
		if (contentService == null)
			return -1;
		INavigatorContentDescriptor sourceOfLvalue = getSource(e1);
		INavigatorContentDescriptor sourceOfRvalue = getSource(e2);
		
		Object parent;
		if (parentPath == null) {
			parent = viewer.getInput();
		} else {
			parent = parentPath.getLastSegment();