\showcolorstruts

\setupbodyfont[dejavu]

\switchtobodyfont[modern]

\enabletrackers[profiling.show]
% \enabletrackers[profiling.trace]

\starttext

\starttexdefinition demo-profile-1 #1
    \framed
        [align=normal,profile=#1]
        {xxx$\frac{1}{\frac{1}{\frac{1}{2}}}$
         \par
         $\frac{\frac{1}{\frac{1}{2}}}{2}$xxx}
\stoptexdefinition

\startTEXpage
    \texdefinition{demo-profile-1}{none}
    \texdefinition{demo-profile-1}{fixed}
    \texdefinition{demo-profile-1}{halffixed}
    \texdefinition{demo-profile-1}{quarterfixed}
    \texdefinition{demo-profile-1}{eightsfixed}
\stopTEXpage

\stoptext
