Hi all. 

If I want to set the space between columns in a MathML <mtable>, how do I do it?

Minimal non-working example below (set the attribute columnspacing to anything you like and it seems to be ignored). Is this a bug or is there a feature I've missed? 

\usemodule[mathml]

\starttext

\xmlprocessdata{}{<formula>
<math xmlns='http://www.w3.org/1998/Math/MathML'>
 <mtable columnalign="right center left" columnspacing="1em">
  <mtr>
   <mtd><mi>a</mi><mi>b</mi></mtd>
   <mtd><mo>=</mo></mtd>
   <mtd><mi>c</mi><mi>d</mi></mtd>
  </mtr>
  <mtr>
   <mtd><mi>e</mi><mi>f</mi></mtd>
   <mtd><mo>=</mo></mtd>
   <mtd><mi>g</mi><mi>h</mi></mtd>
  </mtr>
 </mtable>
</math></formula>}{}

\stoptext