Support for task lists

[2bndy5]

Currently sphinx/rst do not provide a way that generates HTML that takes advantage of mkdocs-material's task lists (configured using a md extension again).

Example HTML output from mkdocs-material docs

<ul class="task-list">
  <li class="task-list-item">
    <label class="task-list-control">
      <input type="checkbox" disabled="" checked="">
      <span class="task-list-indicator"></span>
    </label>
    Lorem ipsum dolor sit amet, consectetur adipiscing elit
  </li>
  <li class="task-list-item">
    <label class="task-list-control">
      <input type="checkbox" disabled="">
      <span class="task-list-indicator"></span>
    </label>
    Vestibulum convallis sit amet nisi a tincidunt
    <ul class="task-list">
      <li class="task-list-item">
        <label class="task-list-control">
          <input type="checkbox" disabled="" checked="">
          <span class="task-list-indicator"></span>
        </label>
        In hac habitasse platea dictumst
      </li>
      <li class="task-list-item">
        <label class="task-list-control">
          <input type="checkbox" disabled="" checked="">
          <span class="task-list-indicator"></span>
        </label>
        In scelerisque nibh non dolor mollis congue sed et metus
      </li>
      <li class="task-list-item">
        <label class="task-list-control">
          <input type="checkbox" disabled="">
          <span class="task-list-indicator"></span>
        </label>
        Praesent sed risus massa
      </li>
    </ul>
  </li>
  <li class="task-list-item">
    <label class="task-list-control">
      <input type="checkbox" disabled="">
      <span class="task-list-indicator"></span>
    </label>
    Aenean pretium efficitur erat, donec pharetra, ligula non scelerisque
    </li>
</ul>

I'm not sure how popular the feature is, but I figured I'd discuss the implementation here before submitting a proposal.

About ideal syntax

I would prefer to be able to use the GitHub-flavored MD style of task lists (as used in upstream). This way users migrating from mkdocs to sphinx would be faced with less friction.

.. md-task-list::
    - [x] Lorem ipsum dolor sit amet, consectetur adipiscing elit
    - [ ] Vestibulum convallis sit amet nisi a tincidunt
        .. md-task-list::
            * [x] In hac habitasse platea dictumst
            * [x] In scelerisque nibh non dolor mollis congue sed et metus
            * [ ] Praesent sed risus massa
    - [ ] Aenean pretium efficitur erat, donec pharetra, ligula non scelerisque

There may be nothing stopping the user from implementing this on their own, but the styling from upstream (& thus this theme) is desirable.

About persistence

As noted in the upstream's docs, checkbox states aren't persistent. Although this could easily be done with a little extra JS from the user's end.

[jbms]

It is hard to imagine a use case for letting the user click on the checkboxes to change their state.

I think your syntax choice is reasonable.

I wonder about the md prefix --- I think the use of md in the css classes refers to mkdocs. We could just have it be task-list.

[2bndy5]

I always thought the CSS's md stood for "material design".

No objections to using task-list since there doesn't seem to be any [published] sphinx extension (that I could find) that modifies the list's marker for this scenario. Honestly, I think this was primarily meant to support GFM syntax, but it looks pretty enough (and I'm a completionist at heart).

[2bndy5]

I did manage to find this thread: https://groups.google.com/g/sphinx-users/c/EzuDSNDA5DI/m/uoHmhJCdAgAJ?pli=1