Right now, I think you need an add-on for those things. For background, Firefox has the general approach of maintaining two contexts: regular windows are one, and private windows are another. Each context has its own cookie jar. When the last private window is closed, that context is destroyed. This approach doesn't mix private tabs into regular windows and regular tabs into private windows. Recently, Firefox introduced the concept of containers and container tabs. This lets you create many new contexts with their own cookie jars, for example, if you want to log into a site as two different users in different tabs. These container tabs can be in any regular windows (I don't ''think'' they would work in private windows, but I never played with it). Mozilla published an add-on to make it easier to work with containers: https://addons.mozilla.org/firefox/addon/multi-account-containers/ I suspect that future development will keep private windows as a more simplified concept and put fancier features into containers, but I certainly don't keep up with such things in detail. ''All of that is by way of introduction for the main message, which is:'' Here in support we work with the Firefox we have today and can suggest relevant features, settings changes, and workarounds. If you want to propose changes to future versions of Firefox, you can submit suggestions through one or more of the following links: * Feedback: https://qsurvey.mozilla.com/s3/FirefoxInput/ * Discourse: https://discourse.mozilla.org/c/firefox-development * Reddit: https://www.reddit.com/r/firefox/ * Twitter: https://twitter.com/firefox * Facebook: https://www.facebook.com/Firefox