I noticed that in the latest versions of Firefox when I open a private browsing session, it is always started in a new window, rather than in the current one.
I don't use this feature extensively (mainly when I'm not on my computer) but I'm fairly sure that I used to have the private session in the current opened window, rather than in a new one.
Is it possible to revert to the old behaviour? If possible, without having to use an extension because, like I said, I usually use this feature on computers that don't belong to me.