Seems indeed to be the best solution overall. But please also comment on the "another idea" from below, about adding mini-tabs to the sidebar.

Well you could:
1) Make CN's window wider
2) Decrease the sectionbar.tab.width.min parameter

Thank you Stuart for this comment! I agree that using the right side for tabs is not the best idea. Probably the best solution would be to provide 2 sets of tabs for notebooks and sections, where the user can pick the position of each. 

Also here's another idea:
- make sidebar full-height, and add tabs to it: "Notebooks", "Tags", "Time", "Link" (using icons instead of text to keep it narrow)
- list all open notebooks on the Notebooks tab
- keep section tabs on top of notes list.

I agree that this is practical, but I think we can do better. Probably if we make the sidebar full-height, it'll provide a better visual cue. Actually even 2 rows of tabs with configurable positions looks better to me)

Agreed!

Thanks for the mockup! To me this looks is a bit illogical - notebooks (databases) include sections, yet appear to be subordinate to them.

Thanks! But I think this is not a bug.
en.lang is a necessary file and should not be deleted.

I can't quite visualize this. The tag sidebar is not very wide.. how could it accommodate notebook tabs on top?