As Idris and Hans expected, Ruby was the culprit. I had installed Ruby before downloading mswincontext.zip, as that was what I used to do in the old days with a Miktex installation.

After following exactly these directions:  http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/173018

Scite now works on context documents.

I tried to add metapost.properties to the global with "import metapost". I can "Build" a file, but the "Go" command does not work because I don't have gv installed. So I opened metapost.properties and tried changing the gv command to gsview32 (and even tried "c:\Program Files\ghostgum\gsview\gsview32.exe"), but neither worked.

Any suggestions how I can get the "go" command to work?

Secondly, what would I do to compile a metapost file in scite directly into PDF? I am aware of context way with processMPbuffer and other assorted tricks, and I am aware of mptopdf, but what I am looking for is to configure Scite to compile the metapost file and open it in acrobat reader.

Here is the test file I am trying to compile.

beginfig(1);

numeric u; 10u=4in;

drawdblarrow (-5u,0)--(5u,0);

drawdblarrow (0,-5u)--(0,5u);

endfig;

end.