On 2021-12-26 11:36, juh via ntg-context wrote:
> Hi all,
>
> I am looking for a way to make startstoplines likes this:
>
>
> This is a long line
>      that breaks,
> the second line,
> the third line.
>
> So if a line in the poem is too long it shall break and indent.
>
> TIA
> juh

You can play with something based on the following, which I made it 
following suggestions from others. There may well be other ways, but 
this works for me.

    \define\Poemindent{3em}
    \define\Poeminset{14em}
    \definedelimitedtext[Poe]
    \setupwhitespace[medium]
    \showframe

    \startbuffer[Poem]
       This is a long line that breaks,
       the second line,
       the third line.

       The second stanza starts.
    \stopbuffer

    \setupdelimitedtext[Poe][
       rightmargin=\Poeminset,
       leftmargin={\dimexpr\Poemindent+\Poeminset\relax},
           before={\setuplines[
                        before=,
                     inbetween={\blank[small]},
                         after=,
                    ]
                   \startlines
                   \setupindenting[-\Poemindent,yes]
                   \startparagraph},
            after=\stopparagraph
                  \stoplines,
      ]

    \starttext

    \startparagraph

      Here comes a poem – watch the lines break!

    \stopparagraph

         \startPoe
           \inlinebuffer[Poem]
         \stopPoe

    \startparagraph

      Now, it is gone. Good-bye.

    \stopparagraph

    \stoptext

-- 
Rik