Mobile first (even for desktop)
I'd urge you to take a mobile-first approach, even if this interface will never be presented on a mobile device.
Mobile, in this context, means 'a small screen' (and not 'on the go'), and basically means that you work the design bottom-up, rather than top-down.
In other words, you start with atomic content/actions/use cases, group them together (into so called 'sub-views'), and then start composing sub-views into bigger views.
In your case
I think that it is clear by your design that the tabs and the next button are grouped; once users are interested in the tabs area, it seems reasonable for the interest to remain on that subview.
The problem with your design
Scalability wise, I wonder where will you put error messages if such may need to be shown?
Consider vertical nav
Your has 3 levels of hierarchy (Section/Page/Tab) and it seems you have chosen the same strategy for each level, whereas in practice mixing things up a bit could help (see more in this question).
Consider flex layout
Another common problem with your design is that the interface is potentially too high to fit into the display this means that users either miss what's on top, or what's on the bottom.
In the days of desktop there where far less of these issues because layout options were far more advance than web page layouts. Recently flex layout were introduced and are now supported by all modern browsers (ExtJS, by the way, offered such layout for years now).
What flex layout allows you to do is to determine the scrollable areas of the screen, which means that neither the tabs, nor the next button will move on scroll.