Connect to window resize / move signal

[Tim Cuthbertson <tim gfxmonk net>]

In Meta.gir I can see that WindowActor has some useful signals to tell
when a user has resized or moved a window (namely size-changed and
position-changed). I would like to connect these signals, but I can't
find a way to access the window's actor. MetaWindow.actor (the obvious
guess) doesn't exist, and I can't find any methods in Meta.gir that
return a WindowActor.

Am I looking in the wrong direction? Is there another signal I should
be connecting to that will tell me when a window has been moved or
resized by the user? If not, how do I get to a MetaWindow's
WindowActor?

Thanks,
 - Tim.