You can click on the Google or Yahoo buttons to sign-in with these identity providers,
or you just type your identity uri and click on the little login button.
I think this is related to https://www.cubicweb.org/ticket/3316345
I deprecate this ticket for now.
Ticket #3292512 - latest update on 2013/12/09, created on 2013/11/13 by Dimitri Papadopoulos