FB.getLoginStatus not calling its callback

Question

The title really says it all. Under some (undetermined) conditions FB.getLoginStatus() just stops working and won\'t invoke the callback I gave it. The only interesting clues

Answer 1

Just posting a situation I had were calling FB.getLoginStatus got absolutely no response.

My application is designed to run in a tab, and I only entered the Page Tab URLs on the app admin page, and not the App On Facebook (i.e. Canvas) URLs. The tab loads perfectly, but any calls to the FB JS SDK provoke no response.