simple background with context and simpleslides

slides.tex

\usemodule[simpleslides]

\usetypescriptfile[type-optical]

\setuplayout[textwidth=5in]

\definefontfeature
   [default][default]
   [mode=node,language=dflt,script=latn,onum=yes,tnum=yes,
        expansion=quality,protrusion=quality]

\usetypescript[minion]
\setupbodyfont[minion]

\definefont [interludefont][name:minion at 48pt]

\setupalign[hanging, hz]

\setupcolors[textcolor=white]

\startuseMPgraphic{simpleslides:MP:horizontal}
   StartPage ;
   fill Page withcolor black ;
   StopPage ;
\stopuseMPgraphic

\defineoverlay
   [simpleslides:background:horizontal]
   [\useMPgraphic{simpleslides:MP:horizontal}]

\defineoverlay
   [simpleslides:background:vertical]
   [\useMPgraphic{simpleslides:MP:horizontal}]

\defineoverlay
   [simpleslides:background:title]
   [\useMPgraphic{simpleslides:MP:horizontal}]

% add 'interlude' macro

\def\Interlude{\dowithpargument\doInterlude}

\def\doInterlude#1%
   {\page
     \null
     \vfill \vfill
    \startalignment[center]
      \let\\\crlf
      \interludefont
        \setupinterlinespace[big]
       #1
       \endgraf
   \stopalignment
    \vfill \vfill \vfill
    \page}


% Now for the rest of the presentation

\setupTitle
   [title={Presentation Title},
    author={Jane Doe},
    date={April, 2010}]

\starttext

\placeTitle

\SlideTitle{A quote}

\input tufte

\Interlude{Test Interlude Heading}

\stoptext