globaltoc_maxdepth

[petsuter]

Is your feature request related to a problem? Please describe.

It is currently impossible to configure the sidebar TOC to collapse and expand to the current page, while also limiting the local TOC to depth 1.

Small example project from #7171

Describe the solution you'd like

The globaltoc_maxdepth theme option should allow configuring the sidebar independently from the local TOC.
Then:

html_theme_options = {
    'globaltoc_collapse': True,
    'globaltoc_maxdepth': -1,
}

should make the sidebar behave as desired, even when the local TOC's are limited like this:

.. toctree::
   :maxdepth: 1
   
   sub/index

Describe alternatives you've considered
I've tried many combinations of the existing theme options, toctree directive options, :tocdepth:, :titlesonly:, :hidden:, :includehidden:, globaltoc_collapse, collapsiblesidebar etc.

Additional context

• @mgeier suggested in The sidebar does not expand when the ToC depth is limited #7171 I should open this issue
• @tk0miya previously discussed it in Add globaltoc_collapse and globaltoc_includehidden options #7443