\setupcolors[state=start]
\setuppagenumbering[location=]
\setMPtext{titleentry}{xxx}
\setuphead
[title]
[textcommand=\TITLE,
page=right,
before=,
after=\blank,
inbetween=,
header=,
textstyle=,
style=]
\def\TITLE#1%
{#1\setMPtext{titleentry}{#1}}
\setupbackgrounds
[page]
[background=page]
\defineoverlay[page] [\useMPgraphic{page}]
\startuseMPgraphic{page}
StartPage;
save r;
picture r;
r := textext.rt(\MPstring{titleentry});
r := r shifted (.5Hsize[Text],.5Vsize[Text]);
draw r withcolor darkred;
StopPage;
\stopuseMPgraphic
\starttext
\title{Some Title}
Some texts.
\page[yes]
Some texts.
\stoptext