mtable borders etc

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.