bug#6049: 24.0.50; Newline sometimes get swallowed in Bidi display

[David Kastrup]

Start the Emacs hello file with C-h h.  Move the cursor on the
right-to-left mark in the Arabic line (it is enclosed by two parens, the
known compositing bug).  Press C-l for recentering.  Sometimes the
following line (Bengali) is mangled into the Arabic line.  It is not
clear to me when this happens: it apparently depends on the window
size/the current window contents non-locally.  I include a screenshot of
when this happens.

In GNU Emacs 24.0.50.1 (i686-pc-linux-gnu, GTK+ Version 2.20.0)
 of 2010-04-27 on lola
Windowing system distributor `The X.Org Foundation', version 11.0.10706000
configured using `configure  '--prefix=/usr/local/emacs' 
'--without-toolkit-scroll-bars' 'CFLAGS=-O2 -fno-crossjumping -g''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  TeX-PDF-mode: t
  desktop-save-mode: t
  minibuffer-electric-default-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t
  view-mode: t

Load-path shadows:
None found.

Features:
(shadow emacsbug pp descr-text thai-util thai-word mule-util lao-util
help-mode view sort qp gnus-cite smiley ansi-color mail-extr gnus-async
gnus-bcklg gnus-ml disp-table nnfolder parse-time timezone nnnil pop3
nnml nndraft nnmh auth-source netrc gnus-agent gnus-srvr gnus-score
score-mode nnvirtual gnus-msg gnus-art mm-uu mml2015 epg-config mm-view
smime password-cache dig mailcap nntp gnus-cache gnus-mlspl gnus-sum
nnoo gnus-group time-date gnus-undo nnmail mail-source format-spec
gnus-start gnus-spec gnus-int gnus-range message rfc822 mml mml-sec
mm-decode mm-bodies mm-encode mail-parse rfc2231 rfc2047 rfc2045
ietf-drums mailabbrev gmm-utils mailheader gnus-win diary-lib
diary-loaddefs cal-menu calendar cal-loaddefs doc-view image-mode vc-cvs
info sh-script executable make-mode dired-x dired-aux dired meta-mode
latexenc lilypond-mode compile comint ring conf-mode newcomment
jka-compr scheme vc-git cc-mode cc-fonts cc-menus cc-cmds cc-styles
cc-align cc-engine cc-vars cc-defs vc-rcs preview prv-emacs byte-opt
reftex-vcr reftex-dcr reftex-auc reftex reftex-vars tex-bar tex-buf
toolbar-x noutline outline font-latex bytecomp byte-compile latex
easy-mmode edmacro kmacro tex-style tex regexp-opt easymenu advice
help-fns advice-preload desktop minibuf-eldef gnus gnus-ems nnheader
gnus-util mail-utils mm-util mail-prsvr wid-edit cus-start cus-load
preview-latex tex-site auto-loads server tooltip ediff-hook vc-hooks
lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image fringe
lisp-mode register page menu-bar rfn-eshadow timer select scroll-bar
mldrag mouse jit-lock font-lock syntax facemenu font-core frame cham
georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese hebrew greek romanian slovak czech european ethiopic
indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple
abbrev loaddefs button minibuffer faces cus-face files text-properties
overlay md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
dynamic-setting system-font-setting font-render-setting gtk x-toolkit x
multi-tty emacs)

-- 
David Kastrup