In my case I want to use one app to get some data with the graph API. Each of my users have a subdomain like http://user.mydomain.com. But when I set up my FB app I can only use one website in the section 'Select how your app integrates with Facebook'.
Is the wilcard working? (I mean http://*.mydomain.com)
Thank you for your help!
If you put mydomain.com in the App Domain field, it will allow any subdomains from that domain to work.