Facebook/twitter "instant" login
We have a system working with Spring Social and have implemented the "login with facebook" and "login with twitter" buttons. We have received a request to add the facility to perform an "instant" login. The request relates to a hypothetical user who has already linked their account on our system to say Facebook and is currently logged into Facebook but not to our system. I want to know if there is some way to log the user straight into our system as soon as they visit the front page without first requiring them to click on a "login with Facebook" button.
My questions therefore are:
(1) Is it possible to perform such an "instant" login with Spring Social?
(2) If not, is it even theoretically possible with another framework?
Thanks in advance.