Awesome, thank you! Just what I was looking for, sorted my trees (symbols) back to front. I have plenty of use for this for perspective illustrations using symbols or repeated objects.
I know this post is over 4 years old now but I just wanted to say thank you. I've been working on a perspective script for some time now trying to get it all to sort by Zorder and this solved my problems in a lot easier fasion. I don't know if you ever get on these forums or not anymore but thank you very much @David_Entwistle