Feature Request: Option to disable setext headers in markdown mode

I know that setext headers are part of the commonmark spec, but our users find them unexpected and confusing (particularly when only a single character is used), in part because we style cm-header-2 to match the font size it will be rendered at

Would it be possible to add an option to disable setext headers to the markdown modeConfig in the same way other markdown features can be enabled/disabled like strikethrough

Alternatively, the spec says

If a line containing a single - can be interpreted as an empty list items, it should be interpreted this way and not as a setext heading underline.

which if implemented would largely solve our issue as well.

Thanks very much 👍

[marijnh]

That mode isn't being actively maintained, but if you submit a pull request I'll review it.

Thanks as always @marijnh for being such a responsive maintainer 👍