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
for (int i = 0; i < items.length; i++) {
			Item item = items[i];
			Object data = item.getData();
			if (data != null) {
				
				
				boolean expanded = expandedElements.remove(data) != null;
				if (expanded != getExpanded(item)) {
					if (expanded) {
						createChildren(item);
					}
					setExpanded(item, expanded);
				}
			}
			if (expandedElements.size() > 0) {
				internalSetExpanded(expandedElements, item);
			}
		}
	}
	/**
	 * Sets the expanded state of all items to correspond to the given set of
	 * expanded tree paths.
	 * 
	 * @param expandedTreePaths
	 *            the set (element type: <code>TreePath</code>) of elements
	 *            which are expanded
	 * @param widget
	 *            the widget
	 */
	private void internalSetExpandedTreePaths(