Scenario: User is logged in User stays idle until his session expires. He doesn't notice it's expired since there is no notice. Meanwhile he is still looking at a particular thread. User makes a post via quick reply. Upon hitting the post reply button, a modal window pops open ("The following error occurred: You must be logged-in to do that.") with the login form. Upon filling out the login form in the modal window, the user is returned to the previous thread. But the reply text is lost. (related: in step 2, xF is continuously trying to save a draft, although it's naturally returned with a 403 error).