Facebook API - callback page when someone logs off

We are using Facebook connect, but I'm sure other people have this problem... Unless we poll on the server side, there must be some way Facebook tells us right?

I'm not talking about if someone logs out of Facebook from 开发者_开发百科our page, I'm talking about if someone has our website open, logs out of Facebook from another tab...

I know we can make callback pages for when a person REMOVES the app, ADDs the app, but what about when a user just simply logs out? \ Here is why it's important for us: we have a real time flash game, and it's expensive for us to check every few seconds if everyone who is in the game is actually logged in.

What we want to do is have a php page callback send a message to our flash game when someone logs off, and then that would kick the user off the game.

if you are using the javascript sdk for login, see https://developers.facebook.com/docs/reference/javascript/FB.Event.subscribe/