Add hover text on table header

[nojaf]

📝 Summary

We would like to provide some (static) hover text on table header columns.

🔍 Description of Changes

I went with an approach similar to text_justify_columns.
The use-case if to further explain what the table does to other team members.

📋 Checklist

• I have read the contributor guidelines.
• For large changes, or changes that affect the public API: this change was discussed or approved through an issue, on Discord, or the community discussions (Please provide a link if applicable).
• I have added tests for the changes made.
• I have run the code and verified that it works as expected.

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Project	Deployment	Preview	Comments	Updated (UTC)
marimo-docs	Ready	Preview	Comment	Sep 23, 2025 7:54am

[mscolnick]

@nojaf i wonder if maybe this should be more descriptive like: header_info or header_descriptions. this way we can use it more in just hover? i would also propose putting it inside a little <InfoIcon/> to signify it has some info (because you may not cover all headers).

@Light2Dark what are your thoughts?

[Light2Dark]

I like the InfoIcon idea too and use TooltipContent instead of title. The accurate name for this param would be header_tooltip I think, but do you think we would use this in diff ways @mscolnick .

some inspiration from ag-grid: https://www.ag-grid.com/javascript-data-grid/tooltips/#top

[Light2Dark]

could we add a test for this

[nojaf]

[Light2Dark]

hey @nojaf , would you mind fixing the test and lint errors. I will help to merge and clean up after that.

[nojaf]

@Light2Dark I don't quite understand why tests like FAILED tests/_utils/test_uv_tree.py::test_complex_project_tree_raw_snapshot - AssertionError are no longer working.

[Light2Dark]

thanks @nojaf , I'll have a look but I think unrelated. thanks for the work!

[Light2Dark]

I'm going to make some improvements on this.