libseed-list Gtktextview.js sample crashes. How to debug? How to help?

[Osmo Antero Maatta <osmoma gmail com>]

Hello,
I downloaded some examples from git://git.gnome.org/seed-examples.
$ git clone git://git.gnome.org/seed-examples

One of the important samples (gtktextview.js ) crashes.

$ seed gtktextview.js

*** glibc detected *** seed: malloc(): memory corruption: 
0x000000000236b290 ***
======= Backtrace: =========
/lib/libc.so.6(+0x774b6)[0x7f52ccef64b6]
/lib/libc.so.6(+0x7b55f)[0x7f52ccefa55f]
/lib/libc.so.6(__libc_malloc+0x6e)[0x7f52ccefb38e]
/lib/libglib-2.0.so.0(g_malloc+0x25)[0x7f52cc9e1305]
/lib/libglib-2.0.so.0(g_strjoin+0xb7)[0x7f52cc9fa437]
/usr/lib/libseed.so.0(seed_struct_prototype+0x50)[0x7f52cd43148f]
/usr/lib/libseed.so.0(seed_make_struct+0xad)[0x7f52cd431635]
/usr/lib/libseed.so.0(seed_gi_argument_make_js+0x441)[0x7f52cd43628b]
/usr/lib/libseed.so.0(+0xf04a)[0x7f52cd42e04a]
/usr/lib/libwebkit-1.0.so.2(+0xa1993e)[0x7f52cbda793e]
/usr/lib/libwebkit-1.0.so.2(+0xa65830)[0x7f52cbdf3830]

My system is Ubuntu 10.10 and the version of Seed is

$ seed --version
Seed 2.31.91

The sample code is here:
http://git.gnome.org/browse/seed-examples/tree/gtktextview.js

These lines cause the crash.
  buffer.get_start_iter (begin);
  buffer.insert(begin, "Hello GtkTextView world.", -1);

Would it help if I edit the function or parameter definition in 
"/usr/share/gir-1.0/Gtk-2.0.gir". I mean if there is a problem with 
direction="out" setting (or something like that).

<method name="get_start_iter"
...
<parameters>
<parameter name="iter"
                     direction="out"
                     caller-allocates="1"
                     transfer-ownership="none">
<doc xml:whitespace="preserve">iterator to initialize</doc>
<type name="TextIter" c:type="GtkTextIter*"/>
</parameter>
</parameters>
</method>

Do I have to re-compile the Gtk-2.0.gir after changes?

Would you be so kind and push me forward with this.

// Osmo Antero (Moma)