Steps to reproduce:
I've recently reinstalled my computer from a ISO-8859-1 system to a UTF-8 one. When GtkFileChooserDialog tried to list a directory containing a filename with an e-acute encoded in ISO-8859-1 on the filesystem, it crashes. Sorry I am unable to make use of gdb to spot the bug ("Cannot find new threads: generic error"?), but I provide detailed reproduction here (for a UTF-8 system):

program:

-=-=---=-=---=-=---=-=--
#include <stdlib.h>
#include <gtk/gtk.h>

int main(int argc, char** argv) {
        GtkWidget * fc;

        gtk_init(&argc, &argv);

        fc = gtk_file_chooser_dialog_new("foo", NULL, GTK_FILE_CHOOSER_ACTION_OPEN, "barz", "1", NULL);

        gtk_file_chooser_set_current_folder(GTK_FILE_CHOOSER(fc), "/tmp/foo");

        gtk_dialog_run(GTK_DIALOG(fc));

        return 0;
}
-=-=---=-=---=-=---=-=--

bang:

# mkdir /tmp/foo
# touch foo/`perl -e 'print pack("H*", "E9")'`
# gcc t.c `pkg-config gtk+-2.0 --cflags --libs` && ./a.out
*** glibc detected *** ./a.out: free(): invalid next size (fast): 0x082443c0 ***
======= Backtrace: =========
/lib/i686/libc.so.6[0xb770ac64]
/lib/i686/libc.so.6(cfree+0x96)[0xb770cd16]
/usr/lib/libgio-2.0.so.0[0xb7b227ff]
======= Memory map: ========
08048000-08049000 r-xp 00000000 08:01 1163970    /tmp/a.out
08049000-0804a000 rw-p 00000000 08:01 1163970    /tmp/a.out
08096000-0825d000 rw-p 08096000 00:00 0          [heap]
b6300000-b6321000 rw-p b6300000 00:00 0 
b6321000-b6400000 ---p b6321000 00:00 0 
b648c000-b6499000 r-xp 00000000 08:01 884790     /lib/libgcc_s-4.3.2.so.1
[...]

Stack trace:


Other information: