Bug 164509 Breaking API change: ColumnViewer#getItemAt(Point)
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
*            {@link TreePathViewerSorter}
	 * @return the index to use when inserting the element.
	 * 
	 */
	private int insertionPosition(Item[] items, ViewerComparator comparator,
			int lastInsertion, Object element, TreePath parentPath) {
		int size = items.length;
		if (comparator == null) {
			return size;
		}
		int min = lastInsertion, max = size - 1;
		while (min <= max) {
			int mid = (min + max) / 2;
			Object data = items[mid].getData();
			int compare = internalCompare(comparator, parentPath, data, element);
			if (compare == 0) {
				return mid;
			}
			if (compare < 0) {
				min = mid + 1;
			} else {
				max = mid - 1;
			}
		}
		return min;
	}
	/**
	 * Returns the index where the item should be inserted. It uses sorter to
	 * determine the correct position, if sorter is not assigned, returns the
	 * index of the element after the last.