This article is helpful only if you have the following situation:
A web app which uses facebook login to login its users and if a user is logged out from his/her facebook account through another browser tab, then your app dont know that he is logged out out or not from his facebook account and he/she will remain as logged in your web application.Its ok if you have no problem with this situation.But if you want to forcefully logout the user from your application if he is logged out from his facebook account means you can try this example.This example uses periodic ajax calls to facebook's graph api to check whether the user is logged in or not.
So I've been busy making lots of modifications to my views/models/controllers - came to test the app and got a blank screen. Nothing in the application.log file so must be a syntax error somewhere... But which file?