Bug 156883 [Viewers] enhancements to ILazyTreeContentProvider
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
* @see ILazyTreeContentProvider
	 * 
	 * @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);
				}
			}
		}
	}
	public boolean isExpandable(Object element) {
		if (getContentProvider() instanceof ILazyTreeContentProvider) {
			TreeItem treeItem = (TreeItem) internalExpand(element, false);
			if (treeItem == null) {
				return false;
			}
			virtualMaterializeItem(treeItem);
			return treeItem.getItemCount() > 0;
		}
		return super.isExpandable(element);
	}