Calculating the preferred size of a node before layout takes place?

[Mike Hearn]

I'd like to find the calculated height of a node in my window controllers
initialise() method, so I can shrink the height to zero and then animate it
to the right size later. However getHeight and getPrefHeight both return
zero in this method, presumably because it's not been laid out yet.

I tried calling layout() but that didn't help.

I don't want any visual glitches caused by a node being visible and then
immediately resized to invisibility. Is there a solution to my problem? I
feel there must be an obvious one that I'm just overlooking somehow ...

thanks!