private void buildTree(
final TreeItem node,
final TreeElement[] children,
final FunctionalInterfaces.IFunction<Void, Void> callbackIfDone) {
AsyncTree.build(itemMap, node, children, callbackIfDone);
}
protected final void walkTree(
final FunctionalInterfaces.IBinaryFunction<TreeItem, SelectableFeature, Void> perNodeFunction,
final FunctionalInterfaces.IFunction<Void, Void> callbackIfDone) {
AsyncTree.traverse(itemMap, tree.getItem(0), perNodeFunction, callbackIfDone);
}