Looks useful for multilingual documents, e.g. interle= aved lines or linguistic glosses.

The following example worked fo= r me, but I share in case there's a way to do better code from it:
<= div>

\starttext
\newbox\spanishbox
\newbox\englishbox
\n= ewbox\frenchbox

\setbox\spanishbox\vbox\bgroup\red\obeylines
Co= noc=C3=AD a un viajero de una tierra antigua
quien dijo: =C2=ABdos enorm= es piernas p=C3=A9treas, sin su tronco
se yerguen en el desierto. A su l= ado, en la arena,
semihundido, yace un rostro hecho pedazos, cuyo ce=C3= =B1o
y mueca en la boca, y desd=C3=A9n de fr=C3=ADo dominio,
cuentan = que su escultor comprendi=C3=B3 bien esas pasiones
las cuales a=C3=BAn s= obreviven, grabadas en estos inertes objetos,
a las manos que las tallar= on y al coraz=C3=B3n que las aliment=C3=B3.
Y en el pedestal se leen est= as palabras:
"Mi nombre es Ozymandias, rey de reyes:
=C2=A1Conte= mplad mis obras, poderosos, y desesperad!"
Nada queda a su lado. Al= rededor de la decadencia
de estas colosales ruinas, infinitas y desnudas=
se extienden, a lo lejos, las solitarias y llanas arenas=C2=BB.
\egr= oup

\setbox\englishbox\vbox\bgroup\blue\obeylines
I met a travel= ler from an antique land,
Who said=E2=80=94=E2=80=9CTwo vast and trunkle= ss legs of stone
Stand in the desert. . . . Near them, on the sand,
H= alf sunk a shattered visage lies, whose frown,
And wrinkled lip, and sne= er of cold command,
Tell that its sculptor well those passions read
W= hich yet survive, stamped on these lifeless things,
The hand that mocked= them, and the heart that fed;
And on the pedestal, these words appear:<= br>My name is Ozymandias, King of Kings;
Look on my Works, ye Mighty, an= d despair!
Nothing beside remains. Round the decay
Of that colossal W= reck, boundless and bare
The lone and level sands stretch far away.=E2= =80=9D
\egroup

\setbox\frenchbox\vbox\bgroup\darkgray\obeylines =
J=E2=80=99ai rencontr=C3=A9 un voyageur de retour d=E2=80=99une terre a= ntique
Qui m'a dit : =C2=AB Deux immenses jambes de pierre d=C3=A9po= urvues de buste
Se dressent dans le d=C3=A9sert. Pr=C3=A8s d=E2=80=99ell= es, sur le sable,
=C3=80 moiti=C3=A9 enfoui, g=C3=AEt un visage bris=C3= =A9 dont le sourcil fronc=C3=A9,
La l=C3=A8vre pliss=C3=A9e et le rictus= de froide autorit=C3=A9
Disent que son sculpteur sut lire les passions<= br>Qui, grav=C3=A9es sur ces objets sans vie, survivent encore
=C3=80 la= main qui les imita et au c=C5=93ur qui les nourrit.
Et sur le pi=C3=A9d= estal il y a ces mots :
"Mon nom est Ozymandias, Roi des Rois.
V= oyez mon =C5=93uvre, =C3=B4 puissants, et d=C3=A9sesp=C3=A9rez !"
= =C3=80 c=C3=B4t=C3=A9, rien ne demeure. Autour des ruines
De cette colos= sale =C3=A9pave, infinis et nus,
Les sables monotones et solitaires s=E2= =80=99=C3=A9tendent au loin. =C2=BB
\egroup

\dorecurse{\boxline= s \spanishbox}{%
\strut\llap{\hbox to 1.5em{\txx#1\hss}}\boxline \englis= hbox#1\par
\strut\boxline \spanishbox#1\par
\strut\boxline \frenchbox= #1\par =C2=A0
\blank
}
\stoptext

Thank you for the goodies, Hans

Regards,

Jairo :)

El jue., 6 de ago. = de 2020 a la(s) 13:13, Wolfgang Schuster (wolfgang.schuster.lists@gmail.com) escribi=C3=B3:

Hans Hagen schrie= b am 06.08.2020 um 19:26:
> Hi,
>
> I uploaded a new lmtx version ... it has a new mechanism for
> manipulating boxes:
>
> http://www.pragma-ade.com/general/= magazines/mag-1105-mkiv.pdf
>
> (also in distribution)
>
> Of course experimental but I bet that some can think of usage.

The \copyboxline command doesn't stop at the end of the requested line.=

BTW: Is it possible to have unbox command to get the width of the
content in the lines without the spaces at the begin end. This is useful to get the width of first/last line in a box.

%% begin example
\starttext

\setbox0\vbox
=C2=A0 =C2=A0{\hsize=3D4cm
=C2=A0 =C2=A0 one\par
=C2=A0 =C2=A0 two\par
=C2=A0 =C2=A0 three\par
=C2=A0 =C2=A0 four}

\setbox2\ruledhbox{\copyboxline 0 2}
\setbox4\ruledhbox{\boxline 0 3}
%\setbox6=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0\boxline 0 5 % error

[2] [\box2] \par
[3] [\box4] \par
[5] [\box6] \par

\stoptext
%% end example

Wolfgang
___________________________________________________________________________= ________
If your question is of interest to others as well, please add an entry to t= he Wiki!

maillist : ntg-cont= ext@ntg.nl / http://www.ntg.nl/mailman/listinfo/nt= g-context
webpage=C2=A0 : http://www.pragma-ade.nl / http://context.aanhet.net=
archive=C2=A0 : https://bitbucket.org/phg/context-m= irror/commits/
wiki=C2=A0 =C2=A0 =C2=A0: http://contextgarden.net
___________________________________________________________________________= ________