title: How can I detect that a user signed into Facebook?
body: <p>Here is my scenario. When a user opens a browser and goes to facebook.com to sign himself in, I want to be able to detect that and init my Facebook application sign-in process.</p>
  
  <p>Is that possible? I'm asking because I noticed that signing into Facebook itself doesn't get my app signed in automatically, which is not good. </p>
  
  <p>I'd prefer JavaScript client code.</p>