I was excited to read this: " if you move one walkthrough in the tree to be a child of another walkthrough, when the child walkthrough is run, it will run all the steps of its parent walkthrough(s) first"

But in the offline editor I seemgly can't make a workthrough the child of another, at least not with drag and drop, which works fine on other objects. Am I missing anything?

Ah, forget it, I found it myself. For the record: using copy and paste works.

Very nice feature! :-)