CJK Full-Width-Space different double half-width-space/chars

[Fumihito YOSHIDA]

salvaged from:
 - http://slashdot.jp/linux/comments.pl?sid=443938&cid=1536460
 - http://slashdot.jp/~little(/journal/471073

Description:
 - Full-Width-Space("　") is not double of half-width-space, and any half-width chars.
 - It can reproduce in "not in multiples of 3" (10,11,13,14,16...)"
 - It can reproduce in 8.04 - 9.04
 - It can reproduce in GTK textedit.

How to reproduce:
 1) run gedit or any gtk apps.
 2) set your font setting to any fixed fonts.
 3) change font size to "not in multiples of 3" (10,11,13,14,16...)"
 4) type half-width space(" ") and Full-Width-Space("　").
 5) Full-Width-Space is not double of half-width-space.

Packages:
$ dpkg -l | grep gedit
ii gedit 2.26.0-0ubuntu2 official text editor of the GNOME desktop en
ii gedit-common 2.26.0-0ubuntu2 official text editor of the GNOME desktop en

[Fumihito YOSHIDA (hito)]

Is it known fontconfig's problem? (not debian#179519)

[Toshio Ito (debug-ito)]

I can reproduce this bug in Xubuntu 9.10.
I tried both Emacs 23 and mousepad with IPAMonaGothic, and the bug occurred.

emacs23 : 23.1+1-4ubuntu3.1
mousepad : 0.2.16-2ubuntu2
ttf-ipamonafont : release1.0.8-0ubuntu0ja3 (installed from Japanese Team Repository)