static void jDynamicTree_addToNode(final JTree tree, fO node, fO child) {
  swing {
    DefaultMutableTreeNode n = jDynamicTree_findNode(tree, node);
    print("jDynamicTree_addToNode: n=" + n);
    if (n == null) ret;
    if (jDynamicTree_isInDummyState(n)) ret;
    n.add(jDynamicTree_newNode(child));
  }
}