Re: mtable borders etc

On 10/11/2014 22:42, Peter Krautzberger wrote:
> Hi,
>
> The mtable element is limited in terms of columnlines, rowlines, and
> frame. In particular, this has come up on the MathJax user group
> <https://groups.google.com/forum/#!searchin/mathjax-users/I$20guess$20it$27s$20mostly$20a$20matter$20of$20convenience$2C$20as$20maths$20folks$20are$20usually$20quite$20familiar$20with$20TeX$20but$20not$20so$20with$20HTML.$20%7Csort:relevance/mathjax-users/6vMvWrSCSzA/BH-dfMd5tK4J> a
> few years ago and has resurfaced in a bug report for MediaWiki/Wikipedia
> <https://bugzilla.wikimedia.org/show_bug.cgi?id=73169> a few days ago.
>
> Perhaps there's something constructive to be done about it?
>
> Best wishes,
> Peter.
>

extensions are always possible to propose...

In this case, personally, I'm rather lukewarm, latex allows || mainly 
because tabular and array are the same thing, more or less. I'm not sure 
there are that many use case for || in math?

However if a double rule is needed you could model the example in the 
bug report

   |c|c||c|

as

  |c|c|@{\hspace{\arrayrulesep}}c@{}|c|

with an empty cell (ie in tex &&) at the relevant cell boundary.

If we were to extend this in an html+mathml context probably we should
be looking to see some way of specifying how css table cell border
ptoperties are supposed to work here. CSS styling does basically work 
already in firefox as far as I can see, If I take this MDN example
and adapt it to include mtable

https://developer.mozilla.org/en-US/docs/Web/CSS/border-style

It produces the attached


David
(wearing TeX hacker's hat not Math WG one)