How can I authenticate with facebook when in an iframe? Safari blocks the cookies

This is a question for anyone who's ever made an iFrame app in facebook, or a 3rd party widget that would run in a website (I'm doing the latter). How can I authenticate with facebook? It seems that the fbs_ cookie isn't being set when I'开发者_如何学Pythonm on Safari, because the iframe is showing my widget which is on another domain.

I heard that submitting a form with target="self" might cause Safari to treat my domain as "visited" and then the cookies would be set. It seems to work. However, the fbs cookie is STILL not being set after the whole facebook authentication popup is done. Does anyone know why? Please help me figure out how to actually auth with facebook when I'm in an iframe!

Hmm strange -- I found that even in Safari facebook iframe apps work: How does Facebook set cross-domain cookies for iFrames on canvas pages?.

Does http://apps.facebook.com/runwithfriends/ not work for you in Safari?