Bug#456236: xterm: Missing fullwidth glyphs not handled correctly

[Daniel Jacobowitz <dan@debian.org>]

Package: xterm
Version: 229-1
Severity: normal

First you'll need my local unicode font to demonstrate this problem:

  http://www.false.org/~drow/unifont/

Try running this command in an xterm using uni8x16:

  clear; echo nowhere; tput cup 0 0; perl -e 'print pack ("cccccc", 0xE9,0x97,0x9c,0xe9,0x97,0x9c), "Hi\n";'

This writes "nowhere" on the first line, then two missing fullwidth
glyphs, then "Hi".  I reliably get " whHie" on the first line,
i.e. each missing char advanced the cursor two cells but only advanced
some other repainting cursor one cell.  Redrawing the screen, e.g.
by starting and exiting screen to switch into and out of alternate
display, causes the phantom "wh" to disappear.

I can reproduce this with or without screen; it came up using mutt.

I think the font is strange but correct; I tried some other fonts
missing these glyphs and somehow they had the correct widths recorded
for them anyway.

-- System Information:
Debian Release: lenny/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.22 (SMP w/2 CPU cores; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages xterm depends on:
ii  libc6                     2.7-4          GNU C Library: Shared libraries
ii  libfontconfig1            2.5.0-2        generic font configuration library
ii  libice6                   2:1.0.4-1      X11 Inter-Client Exchange library
ii  libncurses5               5.6+20071124-1 Shared libraries for terminal hand
ii  libsm6                    2:1.0.3-1+b1   X11 Session Management library
ii  libx11-6                  2:1.0.3-7      X11 client-side library
ii  libxaw7                   2:1.0.4-1      X11 Athena Widget library
ii  libxext6                  1:1.0.3-2      X11 miscellaneous extension librar
ii  libxft2                   2.1.12-2       FreeType-based font drawing librar
ii  libxmu6                   1:1.0.3-1      X11 miscellaneous utility library
ii  libxt6                    1:1.0.5-3      X11 toolkit intrinsics library
ii  xbitmaps                  1.0.1-2        Base X bitmaps

Versions of packages xterm recommends:
ii  xutils                        1:7.3+7    X Window System utility programs m

-- no debconf information