
\setuplayout[grid=yes]

\setupframed[offset=none,align=right]

\def\mySecTxtCmd#1%
  {\framed
    [width=\dimexpr\textwidth-2em\relax,location=top]
    {\switchtointerlinespace[line=1ex,distance=0pt]#1\endgraf}}

\def\mySecNumCmd#1%
  {\framed[width=2em,location=high]{#1}}

\def\mySecCmd#1#2%
  {\framed
    [framecolor=blue,offset=overlay,align=top]
    {\mySecNumCmd{#1}\mySecTxtCmd{#2}}}


\setuphead
  [section]
  [% style={\ssb\setupinterlinespace[line=1ex]}, % -> wrong effect!
   style=\ssb,
   numberwidth=2em,
   command=\mySecCmd,
   numbercommand=\mySecNumCmd,
   textcommand=\mySecTxtCmd]

\setuphead
  [subsection]
  [textcommand=,
   numbercommand=,
   command=\normalplacehead,
   grid={line,-5pt}] % -> no effect!


\starttext \showgrid
\section{\input tufte}
\input tufte \par
\subsection{Test}
\stoptext

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