Let’s face it. A large majority use the private window feature in browsers to just navigate to one or two websites they don’t want in their search history, and once they have finished viewing their particular website(s), users will often go back to non-private browsing. I think Orion should mirror Safari’s behaviour when closing all private tabs, which is, when you close all private tabs, it does not automatically open a new tab; it just stays in the tab overview to allow for easy access to switch back to non-private browsing.