\enabletrackers[visualizers.all]

% \enabletrackers[visualizers.fontkern]

% \setvisualizerfont

\setupinterlinespace[1.5]

\setuplayout[middle]

\starttext

    \framed{let's see what is involved}

    \blank

    \ruledhbox{\strut test \ruledhbox{test} \kern1cm test}

    \blank

    \ruledhbox to 4cm{\strut test \ruledhbox{test} \kern1cm test}

    \penalty12345

    \penalty\maxdimen

    \ruledhbox to 4cm{\strut test \penalty100 test}

    \input ward

    \startitemize
        \startitem test \stopitem
        \startitem test \stopitem
        \startitem test \stopitem
    \stopitemize

    test\kern-10pt test\kern10pt test

    \kern5pt

    test\kern-10pt test\kern10pt test

    \kern-5pt

    test\kern-10pt test\kern10pt test

    \blank

    \dorecurse{10}{\input ward \par}

\stoptext
