Bug 157174 [Viewers] Refactor new Viewer API
We are yet not completely happy with the API and refactor it.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
* @param index
	 *            the index in the parent's children
	 * @param element
	 *            the new element
	 * 
	 * @see #setChildCount(Object, int)
	 * @see ILazyTreeContentProvider
	 * 
	 * <strong>EXPERIMENTAL</strong>. This class or interface has been added as
	 * part of a work in progress. There is no guarantee that this API will
	 * remain unchanged during the 3.2 release cycle. Please do not use this API
	 * without consulting with the Platform/UI team.
	 * </p>
	 * 
	 * @since 3.2
	 */
	public void replace(Object parent, int index, Object element) {
		if (parent.equals(getInput())) {
			if (index < tree.getItemCount()) {
				updateItem(tree.getItem(index), element);
			}
		} else {
			Widget[] parentItems = findItems(parent);
			for (int i = 0; i < parentItems.length; i++) {
				TreeItem parentItem = (TreeItem) parentItems[i];
				if (index < parentItem.getItemCount()) {
					updateItem(parentItem.getItem(index), element);
				}
			}
		}