\starttext

\hsize12cm

\definedfont[Serif*default,quality] \showfontkerns

\startcombination[1*3]
    {\startoverlay
        {\vbox\bgroup      \setupalign    [nohz]\input tufte\relax\egroup}
        {\vbox\bgroup\green\setupalign  [fullhz]\input tufte\relax\egroup}
     \stopoverlay}
    {fullhz over nohz / glyphs and kerns}
    {\startoverlay
        {\vbox\bgroup      \setupalign  [nohz]\input tufte\relax\egroup}
        {\vbox\bgroup\red  \setupalign    [hz]\input tufte\relax\egroup}
    \stopoverlay}
    {hz over nohz / glyphs only}
    {\startoverlay
        {\vbox\bgroup\green\setupalign[fullhz]\input tufte\relax\egroup}
        {\vbox\bgroup\red  \setupalign    [hz]\input tufte\relax\egroup}
     \stopoverlay}
    {fullhz over hz}
\stopcombination

\stoptext
