centering framed boxes

[Idris Samawi Hamid <ishamid@lamar.colostate.edu>]

Dear gang,

I need a way to overlay four framed boxes so that each inner box is exactly in 
the center of its respective outer box. So far I have the following, but 
careful inspection will show that the boxes are not precisely centered with 
respect to each other. I could go on by trial and error but I'm sure there is 
a direct way to do this.

The text should also be precisely centered between frames.

Thank you in advance!
Idris
=========================================================
\setupoutput[pdftex]%

\setuppagenumbering[state=stop]
\starttext

\setupfloats[location=middle]
\placefigure
[here][tab:enclosure]{4 Stages.}
{
 \midaligned{
 \framed
 [width=12\baselineskip,height=12\baselineskip,strut=yes]
 {\midaligned{Stage 1}
   \midaligned%
   {\framed[width=9\baselineskip,height=9\baselineskip,strut=yes]
     {\midaligned{Stage 2}
       \midaligned%
       {\framed[width=6\baselineskip,height=6\baselineskip,strut=yes]
         {\midaligned{Stage 3}
           \midaligned%
           {\framed[width=3\baselineskip,height=3\baselineskip,strut=yes]
            {\midaligned{Stage 4}}
           }
         \midaligned{\null}}%
       }
     \midaligned{\null}}%
   }
 \midaligned{\null}}
 }
}

\stoptext
=========================================================

============================
Professor Idris Samawi Hamid
Department of Philosophy
Colorado State University
Fort Collins, CO 80523