About Undo, you are right, just close the window if you mess up.
About MoveUp and MoveDown, I'm really not sure, to my test, you can definitely move items that themselves being childern of others, which means that they are not top level right?
See this:
We have C carrying D, and E carrying F, both childern of B.
And we choose E and hit Moveup:
And it definitetly works, so I didn't quite understand what do you mean by move up and down only works on top level items. Could it be a language misunderstanding?