Hello all,

Last October Denis Maier complained about a spurious empty line generated with protrusion and bidi active and a full paragraph. (See https://www.mail-archive.com/ntg-context@ntg.nl/msg95916.html or similar on your favorite mail archive.)

I have recreated the issue without involving protrusion. When a paragraph is very full and bidi is on, an extra line seems to be generated. Without bidi there is no extra line. This is quite sensitive, of course, to line width. I have probably 30 instances of it occurring in a tightly-set bibliography. I would assume that it may occur in any text, but have not noticed it in the body of my book.

I have created an example document that shows it. The problem disappears if bidi is turned off (comment out the first non-comment line) but of course then the RTL text is mis-set. In this example, the spurious line appears after the Walt Kelly entry.

This was tested under ConTeXt  ver: 2021.06.18 23:37 LMTX  fmt: 2021.6.21, but is not a new problem with this version. The problem does not occur with MKIV from the same installation.

%% Demonstration of spurious line insertion on full paragraph with bidi active

\setupdirections  [bidi=on,method=unicode]

\definepapersize  [Testing]
                  [width=6.69in]
\setuppapersize   [Testing]

\setuplayout      [width=fit,
                   backspace=1.4in,
                   cutspace=1in,
                   leftmargin=0.65in,
                   rightmargin=0.65in]

\setupwhitespace  [small]

\setupbodyfont    [libertinus,11pt]

\define\SetupBib{
  \spaceskip 0.7\interwordspace plus .5\interwordstretch minus \interwordshrink
  \definedelimitedtext
    [Exdent]
    [leftmargin=1em,
     indenting={yes,-1em},
     indentnext=yes]}

\starttext
  \input jojomayer

  \input klein

  \blank[2*line]

  \SetupBib
  \startExdent

    Kelly, Cynthia C., ed. 2005. {\em Oppenheimer and the Manhattan
    Project: Insights into J.~Robert Oppenheimer, ‘Father of the
    Atomic Bomb’}. Singapore: World Scientific.

    Kelly, Walt. 1953. {\em The Pogo Papers}. New York, NY: Simon
    & Schuster.

    Kuhn, Thomas S. 1962. {\em The Structure of Scientific
    Revolutions}. Chicago, IL: University of Chicago Press.

    Weinreich, Max. 1945. “Der YIVO un di problemen fun undzer
    tsayt (דער ייִוואָ און די פּראָבלעמען פֿון אונדזער צײַט).”
    {\em YIVO Bleter} 25 (1): 3--18. The title is translated as
    {\em The YIVO and the problems of our time}, and also as
    {\em The YIVO faces the post-war world}.

  \stopExdent
\stoptext

Of course, there could be some other mechanism at work here than bidi, but changing that clears the problem in this instance. (It may be the adjustment to spaceskip that I use to tighten up the text in the bibliography, and if it is, I welcome an alternative way to do that.)

--
Rik