Call this function when you want to enforce that the current user is logged into Facebook.
| callback | Function | callback function to be invoked when session is ready. This parameter may be null callback should be a function with no parameters. |
| onCancelCallback | Function | Callback function to be invoked when a user cancels the connect request by clicking the close or cancel buttons onCancelCallback should be a function with no parameters. |
| isUserActionHint | Boolean | provide hint on whether the call is made from user action (onclick, onkeydown, etc.) This hint is generally necessary unless the function is initialized from a Flash object. |