Using an SSOHandler to login on an page does not work, because Firefox will not recognize that the page has been changed. The reason is, that the SSOHandler will redirect back to the same page.
To fix this the page must be redirected with HTTP Response Code 201 to tell Firefox that this page is new.

Steps to reproduce

1) Create SSO Handler, activate
2) Create restricted area
3) Try to access restricted area (Login will appear)
4) Login to restricted area
Result: SSO Handler will login user, but the page will not reloaded by Firefox, so that login screen is shown again).
Refreshing manually will show the content of the restricted area.