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
}
	/**
	 * 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.
	 * 
	 * @param items
	 *            the items to search
	 * @param sorter
	 *            The sorter to use.
	 * @param lastInsertion
	 *            the start index to start search for position from this allows
	 *            optimising search for multiple elements that are sorted
	 *            themself.
	 * @param element
	 *            element to find position for.
	 * @param parentPath
	 *            the tree path for the element's parent or <code>null</code>
	 *            if the element is a root element or the sorter is not a
	 *            {@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;