Roger's extension is an amazingly cool hack. With some of the decoupling mentioned in #24826, the actual switching should get easier.

Regarding cosmetics, I wanted to make a suggestion. The tabs provided by ttk::notebook aren't ideally suited for this task, both visually on some platforms (hello Mac) and also because they're designed for a fixed (small) number of tabs.

One of the better implementations of tabs I've seen is in the Mac editor TextMate. I've attached a set of annotated screenshots as tmtabs.png. It's nice and clean. Doing this as a widget based on the Tkinter canvas looks very feasible.