This is obviously a glitch that has to be fixed, and it wouldn't be such a problem if you were notified of the change by Facebook.
As it is, you only get this message when trying to access an application that doesn't work via http: "Sorry! We can't display this content while you're viewing Facebook over a secure connection (https). To use this app, you'll need to switch to a regular connection (http).".
Softpedia reports that a click on the "Continue" button performs the downgrade to http, but also automatically deselects the secure browsing option.
Until this feature is fixed, you would do well to take this fact into consideration when surfing from unsecured networks.