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
if (children != null) {
			for (int i = 0; i < children.length; i++) {
				Widget item = children[i];
				Object data = item.getData();
				if (data != null) {
					internalRefreshStruct(item, data, updateLabels);
				}
			}
		}
	}
	/**
	 * Removes the given elements from this viewer.
	 * <p>
	 * EXPERIMENTAL. Not to be used except by JDT. This method was added to
	 * support JDT's explorations into grouping by working sets, which requires
	 * viewers to support multiple equal elements. See bug 76482 for more
	 * details. This support will likely be removed in Eclipse 3.2 in favour of
	 * proper support for multiple equal elements.
	 * </p>
	 * 
	 * @param elementsOrPaths
	 *            the elements or element paths to remove
	 * @since 3.1
	 */
	protected void internalRemove(Object[] elementsOrPaths) {
		Object input = getInput();
		
		
		CustomHashtable parentItems = new CustomHashtable(5);
		for (int i = 0; i < elementsOrPaths.length; ++i) {