The problem with tabbed browsing: where's my window?

Mozilla Firefox - Tabbed Browsing

Safari and Firefox have the same problem with tabbed browsing. There's no view that of all open tabs across all containers. So one can flip from container frame to frame and searching tabs within each.

They need a drop down that lists all windows. Ideally the view would be an expanded hierarchy, as in:

container: Name of first tab within the container
- second tab name
- third tab name
container 2
- second tab name
- third tab name
container 3
- second tab name
- third tab name

Maybe this could be a Firefox extension?