% interface=en output=pdftex
\enableregime[utf-8]
\mainlanguage[de] % !!!!

\setupcolors[state=start]
\setupinteraction[state=start]


\starttext

\def\Buttonheight{8mm}
\def\Buttonwidth{40mm}

\def\ButtonUnselected#1{\framed[frame=off,strut=no,offset=overlay,align={right,lohi},
  width=\Buttonwidth,height=\Buttonheight]
  {\xii#1}}
\def\ButtonSelected#1{\framed[strut=no,offset=overlay,width=\Buttonwidth,height=\Buttonheight,
  align={right,lohi},background=color,backgroundcolor=lightgray,frame=on]
  {\xii#1}}

% graphics for active button (only one)
\definesymbol[TbuttonA] [{\ButtonUnselected{\hbox to 2em{~+~}Normal}}] % not selected (mouse pointer is not in area)
\definesymbol[TbuttonB] [{\ButtonSelected{\hbox to 2em{~+~}InArea}}] % selected
\definesymbol[TbuttonC] [{\ButtonSelected{\hbox to 2em{~+~}LMbutton}}] % + left mouse button
% graphics for inactive buttons
\definesymbol[TbuttonX] [{\ButtonUnselected{\hbox to 2em{}Normal}}]
\definesymbol[TbuttonY] [{\ButtonSelected{\hbox to 2em{}InArea}}]
\definesymbol[TbuttonZ] [{\ButtonSelected{\hbox to 2em{}LMbutton}}] % changes to active button, if lmbutton is released in area

% setup for single button
\setupfield[button]
  [width=40mm,
   height=8mm,
   align=right,
   distance=0mm,
   fieldoffset=0bp,
   offset=none,
   strut=no,
   depth=0pt,
   frame=on,
  ]

% setup for radio field
\setupfield[radiofield][vertical] % same for horizontal+\hbox
  [align=right,
   distance=0mm,
   offset=none,
   strut=no,
   fieldoffset=0mm,
   frame=on,
   empty=yes,
   option=empty,
  ]

% Radio1 uses setup defined in 'radiofield'
\definefield[Radio1][radio][radiofield][Button1,Button2,Button3][Button1]
% ButtonN uses setup defined in 'button'
\definesubfield[Button1] [button] [{TbuttonA,TbuttonB,TbuttonC},{TbuttonX,TbuttonY,TbuttonZ}]
\definesubfield[Button2] [button] [{TbuttonA,TbuttonB,TbuttonC},{TbuttonX,TbuttonY,TbuttonZ}]
\definesubfield[Button3] [button] [{TbuttonA,TbuttonB,TbuttonC},{TbuttonX,TbuttonY,TbuttonZ}]


\noindent
\vbox{\forgetall
\field[Button1]
\field[Button2]
\field[Button3]
}

\stoptext
