Mozilla is working on private browsing window in Firefox

While Mozilla has recently formalized the abandonment of a 64-bit version for Windows, the publisher today confirmed work on a long requested feature by users: the private browsing mode by window.

counter to Internet Explorer and Chrome, Firefox is run in a single process, regardless of the number of tabs and windows. That has always been to curb the impact of private browsing mode (which does not record the session): When enabled, it applies to all windows. In Chrome for example, may well have a window for a conventional navigation and other open incognito.

On a blog, Mozilla announced that the work of rewriting the code is well underway and the first experimental Early versions available for testers.

The expected behavior is exactly the same as you can imagine given the screenshots. On the second, you can see two windows: the left one is classical and displays a tab colors Nightly versions of Firefox, the other has a purple symbolizing a tab private browsing.

The editor indicates that this is a very substantial change under the hood of Firefox and invites testers to send feedback. Bugs are still present and certainly these experimental versions are used as such and not in a production environment.
  

Source: Mozilla