If go to Unread Notifications page and select an item with an URL inside, then open the item, there would be set of buttons in the top of the page:
[Done] [Unsubscribe] [Mark as unread] [Save] x
These buttons is a kind of pop up buttons because of the cross button at the end.
But if go by an URL on the page and go back (browser back button), then the buttons disappear and the user have to go to Unread Notifications page again to press Done or Unsubscribe on the item.
Can you restore them on the browser back button?