Apply `heading.numbering` style to integers in thumb indices

[Roel]

I would like to use thumb indices as described here:

How to create a chapter edge index / thumb index?

The counter you want to use is probably just counter(heading). Using a custom selector instead just creates a completely different counter which is not stepped automatically. To get the number of a specific heading, you can then use the at method of the counter as in #let next-heading = query(selector(...)).first() #let number = counter(heading).at(next-heading.location())

But, this solution does not follow the numbering style (e.g. unnumbered chapters or letters in the appendix). I found that:

• thumb indices in unnumbered chapters can be hidden by adding if heading.numbering == none {return}
• #counter(heading.where(level: 1)).display(heading.numbering) shows the current chapter number in the correct style,

So I hoped I could just add .display(heading.numbering) in the correct place in of the solution offered in the link, and wherever I insert it I get an error. Am I just doing something wrong or is there something fundamentally hard I’m missing here?

It would be nice if #number.display(heading.numbering) could be used inside the block, but apparently ‘Type integer has no method display’ and there is not a very simple way around that Number formatting · Issue #3269 · typst/typst · GitHub