You're absolutely correct. It's also true that you have to play around a bit with the container addons to get it functioning as you'd expect, but please believe

You're absolutely correct. It's also true that you have to play around a bit with the container addons to get it functioning as you'd expect, but please believe that you're not alone out there on how you want it to work. For example, my vision of containers was built out with the Containerise extension. A version of that needs to be built into Firefox. To do what you're asking, I haven't looked for addons to do it, but you'd probably have to do it manually. Open a window, then open a container and spawn everything else out from there. Assigning a container to a browser window sounds entirely plausible, useful, and I like it. There's only a few real use cases for containers that make sense or are useful and that's a new one (to me). If Mozilla did that and duplicated Containerise, they'd have yet-another killer feature. I think Mozilla's biggest problem must be management or bureaucracy, because they have a lot of relatively low-hanging fruit like this just waiting.