[Bug 952724] Re: status area scrolled out infinitely (tmux-backend with libvte + VTE_CJK_WIDTH=1)

[Vibhav Pant]

** Changed in: byobu (Ubuntu)
     Assignee: (unassigned) => Vibhav Pant (vibhavp)

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Title:
  status area scrolled out infinitely (tmux-backend with libvte +
  VTE_CJK_WIDTH=1)

Status in byobu:
  Fix Committed
Status in “byobu” package in Ubuntu:
  Confirmed

Bug description:
  When environment varibable "VTE_CJK_WIDTH=1" is set, byobu-tmux is
  scroll-out infinitely.

  How to reproduce:

   1) install precise.
   2) open gnome-terminal
   3) exec:
      $ export VTE_CJK_WIDTH=1; gnome-terminal --disable-factory 

      Notes: if you exec gnome-terminal without disable-factory, gnome-
  terminal will take over the environment variable of parents' initial
  condition, so VTE_CJK_WIDTH will be ignored.

   3') another aproach:
     create  /etc/profile.d/vte_cjk_width.sh file as follows, and session restart(log-out and log-in)
     ------------------------------------------
     $ cat /etc/profile.d/vte_cjk_width.sh
      export VTE_CJK_WIDTH=1
     ------------------------------------------

   4) exec:
      byobu-tmux (or byobu)

  Workaround:
   disable "logo" indicator from byobu-config.
    (if you want edit config directoly,  edit you .byobu/status::tmux_left : "logo" -> "#logo" )

  Root cause:
   byobu-tmux(byobu with tmux backends) use the Ubuntu Logo character from Ubuntu Fonts. Ubuntu Logo char hits "East Asian Ambiguous" problem, that have ambigous-wide, so that switch the wide of rendering at run-time. 

  When VTE_CJK_WIDTH=0 or not set, the Ubuntu Logo wide is 1, but,
  when VTE_CJK_WIDTH=1, the Ubuntu Logo wide is 2. So that cause the scrolling problem.

  
  Background: 
    For historical reason, "VTE_CJK_WIDTH=1" is libvte's workaround of Unicode::"East Asian Ambiguous width" problem, when VTE_CJK_WIDTH=0, the ambigous wide char's wide is 1, therefor VTE_CJK_WIDTH=1 is set, the ambigous wide char's wide is 2.
    In CJK environment(ESP Japanese), that workaround is important for CLI/terminal sessions. If that is not set, the ambigous wide char render without correctness wide. So, I believe that many CLI/terminal users enable the VTE_CJK_WIDTH=1 in their /etc/profile.d/ at Japan.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: byobu 5.16-0ubuntu1
  ProcVersionSignature: Ubuntu 3.2.0-18.28-generic-pae 3.2.9
  Uname: Linux 3.2.0-18-generic-pae i686
  ApportVersion: 1.94.1-0ubuntu2
  Architecture: i386
  Date: Mon Mar 12 13:20:24 2012
  InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
  PackageArchitecture: all
  ScreenRC:
   
  SourcePackage: byobu
  UpgradeStatus: Upgraded to precise on 2012-03-12 (0 days ago)

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