Comment 8 for bug 1298281

It looks like gtk has ended up in a broken state given the error messages after the attempting to open the dialog:

debconf: unable to initialize frontend: Gnome^M
debconf: (Unable to load Gtk -- is libgtk2-perl installed?)^M
debconf: falling back to frontend: Dialog^M
Processing triggers for hicolor-icon-theme ...^M
^M
(gtk-update-icon-cache-3.0:6517): GLib-GObject-CRITICAL **: /build/buildd/glib2.0-2.32.4/./gobject/gtype.c:2722: You forgot to call g_type_init()^M
^M
(gtk-update-icon-cache-3.0:6517): GLib-GObject-CRITICAL **: /build/buildd/glib2.0-2.32.4/./gobject/gtype.c:2722: You forgot to call g_type_init()^M
^M
(gtk-update-icon-cache-3.0:6517): GLib-GObject-CRITICAL **: g_type_interface_add_prerequisite: assertion `G_TYPE_IS_INTERFACE (interface_type)' failed^M
^M
(gtk-update-icon-cache-3.0:6517): GLib-CRITICAL **: g_once_init_leave: assertion `result != 0' failed^M
^M
(gtk-update-icon-cache-3.0:6517): GLib-GObject-CRITICAL **: g_type_add_interface_static: assertion `G_TYPE_IS_INSTANTIATABLE (instance_type)' failed^M
^M
(gtk-update-icon-cache-3.0:6517): GLib-CRITICAL **: g_once_init_leave: assertion `result != 0' failed^M
^M
(gtk-update-icon-cache-3.0:6517): GLib-GObject-CRITICAL **: g_object_new: assertion `G_TYPE_IS_OBJECT (object_type)' failed^M
Segmentation fault (core dumped)^M

Did you happen to catch the core dump?