if (givenNode != null) {
ThumbnailViewChildren childNode = new ThumbnailViewChildren(givenNode, iconSize);
final Node root = new AbstractNode(childNode);
pageUpdater.setRoot(root);
root.addNodeListener(pageUpdater);
em.setRootContext(root);
} else {
Node emptyNode = new AbstractNode(Children.LEAF);
em.setRootContext(emptyNode); // make empty node