I'm looking to have in the menu...

- chapter title centered
- section title left aligned
- for long chapter/section titles split over more than 1line,
vertical space between these chapter/section lines to be
smaller
- left and right margin of (x)pt

\setuppapersize[S6][S6]

\setupbodyfont[14.4pt]

%\showframe

\setuppagenumbering[alternative=singlesided]

\setuplayout
  [width=360pt,
   headerheight=7pt,
   footerheight=7pt,
   margin=0pt,
   backspace=25pt,
   topheight=7pt,
   bottomheight=7pt,
   rightedgedistance=20pt,
   rightedge=180pt]

\setuplist[chapter,section][
    criterium=all,
    aligntitle=yes,
    interaction=all]

\setuphead[chapter][number=yes]
\setuphead[section][number=no]

\setupbackgrounds[text][rightedge][frame=on]

\setupinteraction[
    state=start,
    menu=on,
    page=yes]

\setupnarrower[left=1pt,right=1pt]
%\setupnarrower[left=5pt,right=5pt]

\defineinteractionmenu[myMenu][right]

\startinteractionmenu[myMenu]
    \placecontent[
        criterium=all,
        alternative=b,
%        distance=2pt,                                % no effect
       style=\tfx,                                          % \tfxx is too
small to read
%        offset=5pt,                                    % no effect
%        margin=5pt,                                  % only sets left
margin
%        width=.9\rightedgewidth,              % chapter title gets whacked
out of rightedge
%        maxwidth=.9\rightedgewidth,       % no effect
        interaction=all,
    before=\startnarrower,                     % sets a default left and
right margin, i.e. independent
    after=\stopnarrower]                        % of left/right setting
%        before=,
%        after=]
\stopinteractionmenu

\setupinteractionmenu[myMenu][state=start]

\setupinteractionmenu[right][
%    offset=5pt,                                        % no effect
%        width=.9\rightedgewidth,               % no effect
%        maxwidth=.9\rightedgewidth,           % no effect
%    before=\startnarrower,                          % no effect
%    after=\stopnarrower,                            % no effect
    distance=overlay]

\starttext
    \chapter{This Long Chapter Title}
    \section{This Long Section Title A}
    \input knuth
    \section{This Long Section Title B}
    \input zapf
\stoptext