Invalid text buffer iterator pressing dot keyboard key

[Angel Guzman Maeso]

I noted this issue in quantal, in lucid it previously work perfect. I am spanish with a spanish keyboard layout and spanish locale. When I try to make some simply maths like:

5 * 1,05 it works, because in my spanish locale, the decimal numers are noted with comma and thousand with dot. For example: 100.000,99
But sometimes you want use dot for decimal like:

5 * 1.05 that it is not valid in my locale, but spanish people often use english notation for decimals. Then the character is not written and in console appears this error:

(gcalctool:31135): Gtk-WARNING **: Invalid text buffer iterator: either the iterator is uninitialized, or the characters/pixbufs/widgets in the buffer have been modified since the iterator was created.
You must use marks, character numbers, or line numbers to preserve a position across buffer modifications.
You can apply tags and insert marks without invalidating your iterators,
but any mutation that affects 'indexable' buffer contents (contents that can be referred to by character offset)
will invalidate all outstanding iterators

My locale output:

$ locale
LANG=es_ES.UTF-8
LANGUAGE=
LC_CTYPE="es_ES.UTF-8"
LC_NUMERIC="es_ES.UTF-8"
LC_TIME="es_ES.UTF-8"
LC_COLLATE="es_ES.UTF-8"
LC_MONETARY="es_ES.UTF-8"
LC_MESSAGES="es_ES.UTF-8"
LC_PAPER="es_ES.UTF-8"
LC_NAME="es_ES.UTF-8"
LC_ADDRESS="es_ES.UTF-8"
LC_TELEPHONE="es_ES.UTF-8"
LC_MEASUREMENT="es_ES.UTF-8"
LC_IDENTIFICATION="es_ES.UTF-8"
LC_ALL=

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: gcalctool 6.5.90.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.5.0-1.1-generic 3.5.0-rc3
Uname: Linux 3.5.0-1-generic i686
ApportVersion: 2.5.1-0ubuntu2
Architecture: i386
Date: Wed Aug 29 03:08:51 2012
InstallationMedia:

ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=es_ES.UTF-8
 SHELL=/bin/bash
SourcePackage: gcalctool
UpgradeStatus: Upgraded to quantal on 2012-06-05 (84 days ago)

[Robert Roth (evfool)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. The issue you are reporting is an upstream one and it would be nice if somebody having it could send the bug to the developers of the software by following the instructions at https://wiki.ubuntu.com/Bugs/Upstream/GNOME. If you have done so, please tell us the number of the upstream bug (or the link), so we can add a bugwatch that will inform us about its status. Thanks in advance.

[Angel Guzman Maeso (shakaran)]

Upstream bug reported: https://bugzilla.gnome.org/show_bug.cgi?id=682971