I really liked some of the stuff one could do with fbml so I made my canvas to use fbml in my app settings and then embedded my canvas page using <fb:iframe src="my_url.aspx">
but I now the canvas page is unable to get the session. I get a "Session key invalid or no longer valid" exception.
I see that normally u would create a session with:
string authToken = Request.QueryString"auth_token";
Well, there isn't an auth_token in the query string as the user is already logged into facebook. How does a canvas page inside <fb:iframe> get a session key?