[alacarte] Enforce the use of Gtk 3.0; Gtk 2.0 is no introspecatble and thus does not serve us anyway.

[Jasper St. Pierre <jstpierre src gnome org>]

commit 72ba83a0e26ecfdcce85a716a527c9550451a6d9
Author: Dominique Leuenberger <dimstar opensuse org>
Date:   Sat Jan 12 13:33:03 2013 +0100

    Enforce the use of Gtk 3.0; Gtk 2.0 is no introspecatble and thus does not serve us anyway.
    
    Fixes bug 691599.

 Alacarte/ItemEditor.py |    2 ++
 Alacarte/MainWindow.py |    2 ++
 Alacarte/util.py       |    3 +++
 3 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/Alacarte/ItemEditor.py b/Alacarte/ItemEditor.py
index df33807..83d6601 100644
--- a/Alacarte/ItemEditor.py
+++ b/Alacarte/ItemEditor.py
@@ -18,6 +18,8 @@
 
 import gettext
 import os
+import gi
+gi.require_version('Gtk', '3.0')
 from gi.repository import GLib, Gtk
 from Alacarte import config, util
 
diff --git a/Alacarte/MainWindow.py b/Alacarte/MainWindow.py
index a15f65a..fddbd4f 100644
--- a/Alacarte/MainWindow.py
+++ b/Alacarte/MainWindow.py
@@ -17,6 +17,8 @@
 #   License along with this library; if not, write to the Free Software
 #   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
+import gi
+gi.require_version('Gtk', '3.0')
 from gi.repository import Gtk, GObject, Gio, GdkPixbuf, Gdk, GMenu, GLib
 import sys
 import cgi
diff --git a/Alacarte/util.py b/Alacarte/util.py
index 4414649..2dbf963 100644
--- a/Alacarte/util.py
+++ b/Alacarte/util.py
@@ -19,6 +19,9 @@
 import os
 import xml.dom.minidom
 from collections import Sequence
+
+import gi
+gi.require_version('Gtk', '3.0')
 from gi.repository import Gtk, GdkPixbuf, GMenu, GLib
 
 # XXX: look into pygobject error marshalling