There have been topics on having divider tabs. I would like to expand on this and also request the option of sub-divider tabs. For example...

For something like a planner journal, there would be 12 main divider sections (one per month). Within each month there could be two separate dividers for weekly and daily pages plus any additional dividers for miscellaneous content relative to that month only.

For student notes, the main dividers could be the classes and the sub-dividers could be for various assignments for each class.

If a divider is a MAIN divider, it is accessible from any page in the notebook, but if it is a SUB-DIVIDER, it is only accessible when you are on a page in it’s parent section.

I would like all the dividers to appear in the page browser and to be able to move and duplicate them just as I would ordinary pages. If I move a sub-divider from one parent section to a new one, it would become a sub-divider in the new section, losing all connection to its previous location but retaining the original name. Duplicate names should be allowed.
The tabs (i.e., the clickable portion) should automatically resize and reposition themselves to best fit the allotted space. They should appear in the same order they appear in the page browser. The current section (and sub-divider) tabs should be highlighted in a way that makes it easy to tell which section I am in. Having automatic color coded bands or blocks appear on the outer edges of content pages that match the tab section(s) would also be helpful.

Since there are three edges to every page (if you don’t include the bottom), I would further like to define a divider as either a top, left, or right side divider. This way I can have my months separated from other notes that are not specific to any month, like long-term project notes.

And of course tab dividers should be completely optional. Maybe they can extend outside the edges of current themes so they can be easily added or removed. Since the tabs would be a separate interface element, they should function no matter which tool you are using to make it easier to navigate without switching tools. Or this can be a preference setting that you can turn of and on in case you need to write on a tab.

A button to hide/show tabs in order to increase screen real estate would also be welcome.