Bug 158778 [Viewers] request for remove(parent, index) API on tree viewer
3.3 It would be helpful to have a 'remove(Object parent, int index)' method on the tree viewer to complement that 'replace(...)' and 'setChildCount(...)' APIs. The debug platform requires such a method to implement filtering in virtual tree views. Rather than performing a 'replace/remove' based on elements, the content provider can make one atomic call to remove an element at a specific index.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
*/
	private TreePath internalGetSorterParentPath(Widget parent,
			ViewerComparator comparator) {
		TreePath path;
		if (comparator instanceof TreePathViewerSorter
				&& parent instanceof Item) {
			Item item = (Item) parent;
			path = getTreePathFromItem(item);
		} else {
			path = null;
		}
		return path;
	}
	/**
	 * Compare the two elements using the given sorter. If the sorter is a
	 * {@link TreePathViewerSorter}, the provided tree path will be used. If
	 * the tree path is null and the sorter is a tree path sorter, then the
	 * elements are root elements
	 * 
	 * @param sorter
	 *            the sorter
	 * @param parentPath
	 *            the path of the elements' parent
	 * @param e1
	 *            the first element
	 * @param e2
	 *            the seocnd element
	 * @return the result of comparing the two elements
	 */
	private int internalCompare(ViewerComparator comparator,