Well, that's not very telling either:

<pre>
./st2.py:524: GtkWarning: gtk_list_store_get_value:
  assertion 'VALID_ITER (iter, list_store)' failed
  gtk.main()
./st2.py:524: Warning: g_object_set_property:
  assertion 'G_IS_VALUE (value)' failed
  gtk.main()
./st2.py:524: Warning: g_value_unset:
  assertion 'G_IS_VALUE (value)' failed
  gtk.main()
Fatal Python error: Segmentation fault

Current thread 0x00002b8da5ef1a80 (most recent call first):
  File "./st2.py", line 524 in main
  File "./st2.py", line 535 in <module>
make: *** [run] Speicherzugriffsfehler
</pre>