I am using Omniauth and forcing /auth/facebook to display in a popup (with JS). [Instead of a new window - which is much less user friendly]
The problem is: Omniauth
If you're using heroku, then use this option:
config.omniauth :facebook, ENV['FB_APP_ID'], ENV['FB_APP_SECRET'], {:scope => 'email, offline_access', :client_options => {:ssl => {:ca_file => '/usr/lib/ssl/certs/ca-certificates.crt'}}, :display => 'popup' }
If you're using this with Devise, simply edit your development.rb (and production.rb) to the following;
config.omniauth :facebook, FACEBOOK_API, FACEBOOK_SECRET, :display => 'popup'
Make sure you restart your rails server upon editing these files.
Actually, in the current version of omniauth-facebook, this is what works for me:
:authorize_params => { :display => 'popup' }
At where you set your Facebook ID and secret key, add one more extra option as:
:display => "popup"