I have written some code in C# to integrate facebook with my site, all is working with the redirects, I have a cute little C# handler that processes everything.
I am wondering how to tell if a user is loggen in to facebook when the hit my “login with facebook button”
This is a bit ove a mystery to me. For example, take the stackoverflow.com site, I can clear my cookies, close my browser, logoff of facebook obviously, then logon to facebook in a new browser window and stack overflow knows I am logged in to facebook and automatically logs me in. How the hell do they know I am logged in to facebook?
A new Window, as in a new window of the same browser?
Facebook probably saves a cookie that is read by the browser and then, it does not matter if you are running another instance of the same browser. The location for storing and reading cookies remains the same for the same browser!