Two-column layout with thick vertical rule in ConTeXt

Question

Background

I would like to add a thick rule centered between two columns.

Example Code

A minimum working example that illustrates the issue:

\setupcolors[state=start]

\startuseMPgraphic{StyleVerticalRule}
  thickness := 6.50pt;

  if CurrentColumn < NOfColumns :
    setbounds currentpicture to OverlayBox
      shifted( -3*thickness, 0 );

    draw rightboundary OverlayBox
      withpen pensquare scaled thickness
      withcolor \MPcolor{red};
  fi
\stopuseMPgraphic

\defineoverlay[StyleVerticalRule][
  \useMPgraphic{StyleVerticalRule},
]

\definecolumnset[StyleColumns][
  n=2,
  background=StyleVerticalRule,
]

% Horizontal line below the section header.
\define[2]\StyleSection{%
  \framed[
    frame=off,
    bottomframe=on,
    framecolor=pink,
    rulethickness=1.0pt,
    width=local,
  ]{\vbox{#2}}}


\setuphead[section][
  command=\StyleSection,
  after={\startcolumnset[StyleColumns]},
  aftersection={\stopcolumnset},
]

\starttext
\startbodymatter
  \startchapter[title={Chapter}, reference=sec:my-chapter,]
  \startsection[title={Section}, reference=sec:my-section,]
  \startsubsection[title={Equipment},reference=sec:my-equipment,]
    \input knuth
    \input knuth
  \stopsubsection
  \stopsection
  \stopchapter
\stopbodymatter

\stoptext

Problem

The vertical rule height appears to be \textheight, rather than height of the columns. The code above produces:

The vertical rule extends beyond the subsection header because, I think, it references OverlayBox. I would like to use the column height, not the text height, to produce:

Questions

With respect to multi-column layouts:

• How do you restrict the height of the vertical rule so that it respects the column height (i.e., how do you determine the column height)?
• How would you add sufficient space to the section's column margins so that the vertical rule does not overlap any text?
• What is the required calculation to ensure the vertical rule is centered between the columns (i.e., -3*thickness seems... incorrect)?

I also could not find any definition for OverlayBox, although I found a few examples.

Related

Information that is somewhat related:

• How to place text between two columns and which breaks the rule dividing them in ConTeXt?
• formatting natural table header with conTeXt
• https://tex.stackexchange.com/a/17813/2148
• Creating a grid which fills available text area on a page in ConTeXt?
• http://www.ntg.nl/pipermail/ntg-context/2011/058352.html
• http://wiki.contextgarden.net/TABLE

Answer 1

When using columnsets, your entire page design must be done using columnsets. So, if you want chapter or section heads to span the entire page, you will have to define a columnspan.

For simple two column documents, you can use \startcolumns ... \stopcolumns, or its MkIV replacement \startmixedcolumns ... \stopmixedcolumns. Here is an example:

\setupcolors[state=start]

\startuseMPgraphic{StyleVerticalRule}
  draw OverlayBox;
\stopuseMPgraphic

\defineoverlay[StyleVerticalRule][\useMPgraphic{StyleVerticalRule}]

\definemixedcolumns
  [sectioncolumns]
  [
    n=2, 
    separator=rule,
    rulecolor=red,
    rulethickness=6.5pt,
    balance=yes,
  ]

\setupalign[verytolerant,stretch,hanging]

% Horizontal line below the section header.
\defineframed[sectionframed]
             [
               frame=off,
               bottomframe=on,
               framecolor=pink,
               rulethickness=1.0pt,
               width=local,
               align=normal, % to get a vbox
             ]

\define[2]\StyleSection{\sectionframed{#2}}

\setuphead
    [section]
    [
      command=\StyleSection,
      after={\startsectioncolumns},
      aftersection={\stopsectioncolumns},
    ]

\starttext
\startchapter[title={Chapter}, reference=sec:my-chapter,]
  \startsection[title={Section}, reference=sec:my-section,]
      \startsubsection[title={Equipment},reference=sec:my-equipment,]
        \input knuth
        \input knuth
      \stopsubsection
  \stopsection
\stopchapter

\stoptext

which gives