2012/1/25 Aditya Mahajan <adityam@umich.edu>
Better is to use: \StrikeMeFrame{\mathsurround\zeropoint$#1$}. But for this to work in subscripts and superscripts, you must use math palette. IIRC, \mframed does that. In principle:

\mframed[background=strikeme]{...}

should work (untested).

@Hans: Can we have \definemframed etc as well?

Aditya

so this should work?

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\startuniqueMPgraphic{strikeme}
   path p ; p := OverlayBox topenlarged -ExHeight bottomenlarged -ExHeight ;
   draw llcorner p -- urcorner p withcolor OverlayColor ;
\stopuniqueMPgraphic

\defineoverlay[strikeme][\uniqueMPgraphic{strikeme}]

\def\strike#1{%
\ifmmode%
\mframed[background=strikeme,frame=off]{#1}%
\else%
\inframed[background=strikeme,frame=off]{#1}%
\fi}

\starttext
\startformula
{\strike2a + \strike ab \over \strike a} = a
\stopformula

Works in text, \strike{two}too!

\stoptext