// First, make the change in the properties object.
DefaultMutableTreeNode parentNode=(DefaultMutableTreeNode)node.getParent();
int index = parentNode.getIndex(node);
PropertyKey parentKey = key.getParent();
Prop parentProp = useProps.pget(parentKey);
parentProp.moveChildUp(index);
// Next, make the change in the tree model.
treeModel.useTreeModelListener(false);
parentNode.insert(node, index-1);
treeModel.useTreeModelListener(true);