Hello,
I do not understand why figure 2 does not fit correctly like the other two.
Thank you
Fabrice


\useMPlibrary[dum]

\usemodule[tikz]

\usemodule[pgfplots]
\pgfplotsset{compat=newest}
\usetikzlibrary{positioning}
\usetikzlibrary{calc}

\setuplayout
  [height=middle,
   width=middle,
   backspace=2cm,
   topspace=10mm,
   bottomspace=10mm,
   header=10mm,
   footer=10mm,
   footerdistance=10mm,
   headerdistance=10mm]

\showframe

\starttext

\placefigure[right]{first}{\externalfigure[dummy]}

\placefigure[right]{second}{
  \hbox{
    \starttikzpicture[thick]
\switchtobodyfont[9pt]
\startaxis[
x=3cm,y=3cm,
axis line style = thick,
major tick style=black,
xtick={0,0.25,...,1},ytick={0,0.25,...,1},
ymin=-0.25,ymax=1.25,xmin=-0.25,xmax=1.5,
axis on top=true,
axis lines=middle,
tickwidth=0.15cm,
minor tick num=3,
major tick style = {thick, black},
axis line style = thick,
yticklabels={,,},
xticklabels={,,},
major tick style=black,
extra x ticks={1.25},
extra x tick label={\null},
xlabel=$x$,ylabel=$y$,
every axis x label/.style=
      {
        at={(ticklabel* cs:1)},
        anchor=west
      },
      every axis y label/.style=
      {
        at={(ticklabel* cs:1)},
        anchor=south
      },
      >=stealth]

\coordinate [label=below left  : $A$](A) at (0,0);
\coordinate [label=below right : $B$](B) at (1,0);
\coordinate [label=below right : $C$](C) at (1,1);
\coordinate [label=above left  : $D$](D) at (0,1);
\coordinate (M) at (0.25,0);
\coordinate (N) at (1,0.25);
\coordinate (P) at (0.75,1);
\coordinate (Q) at (0,0.75);

\node[below left] at (M) {$M$};
\node[right] at (N) {$N$};
\node[above] at (P) {$P$};
\node[left]  at (Q) {$Q$};

\node[left] at (0,1){$1$};
\node[below] at (1,0){$1$};

\draw (A)--(B)--(C)--(D)--cycle ;
\draw [draw=red, fill=red!70](M)--(N)--(P)--(Q)--cycle ;

\stopaxis
\stoptikzpicture
  }
}


\placefigure[right]{third}{
  \hbox{
    \starttikzpicture
      \draw[draw=red,fill=red!70] (0,0) rectangle (3,3);
    \stoptikzpicture
  }
}
\stoptext