/**
* @param child the child node the hook should be propagated to.
* @return returns the new hook or null if there is already such a hook.
*/
protected PermanentNodeHook propagate(MindMapNode child) {
PermanentNodeHook hook =
(PermanentNodeHook) getMindMapController().createNodeHook(getName(), child, getMap());
// invocation:
child.invokeHook(hook);
return hook;
}
