23.0.60; Cursor "bolds" some characters when anti-aliasing is on

[BBA]

When anti-aliasing is on, the character to the left of the cursor
sometimes becomes "bold" when the cursor blinks on and off. This
effect is cumulative and disappears when the cursor is moved over the
character but not when it is moved away.

The effect is more pronounced with subpixel rendering and Xft LCD
filtering active, but happens on some characters without it as well.
When LCD filtering is on, it doesn't seem to happen if the cursor is
over whitespace.

For example, note the "2" to the left of the cursor in:
http://img230.imageshack.us/img230/2387/76353846yn2.png

(Font: Bitstream Vera Sans Mono-10.)

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/usr/share/emacs/23.0.60/etc/DEBUG for instructions.


In GNU Emacs 23.0.60.1 (i486-pc-linux-gnu, GTK+ Version 2.12.9)
 of 2008-03-19 on vernadsky, modified by Debian
 (emacs-snapshot package, version 1:20080228-1ubuntu1)
Windowing system distributor `The X.Org Foundation', version 11.0.10400090
configured using `configure  '--build' 'i486-linux-gnu' '--host'
'i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib'
'--libexecdir=/usr/lib' '--localstatedir=/var'
'--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes'
'--enable-locallisppath=/etc/emacs-snapshot:/etc/emacs:/usr/local/share/emacs/23.0.60/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.0.60/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/23.0.60/leim'
'--with-x=yes' '--with-x-toolkit=gtk' '--enable-font-backend'
'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu'
'CFLAGS=-DDEBIAN -DSITELOAD_PURESIZE_EXTRA=5000 -g -O2' 'LDFLAGS=-g
-Wl,--as-needed' 'CPPFLAGS=''

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:
  tooltip-mode: t
  tool-bar-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
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t