[pitivi] Set emblem-system-symbolic for menu icon before gtk 3.13

[Thibault Saunier <tsaunier src gnome org>]

commit e34bbfebb505071141b46608d1f4f80a40b11fb9
Author: Lubosz Sarnecki <lubosz gmail com>
Date:   Wed Sep 24 14:47:11 2014 +0200

    Set emblem-system-symbolic for menu icon before gtk 3.13

 data/ui/mainmenubutton.ui |    2 +-
 pitivi/mainwindow.py      |    5 +++++
 2 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/data/ui/mainmenubutton.ui b/data/ui/mainmenubutton.ui
index adedff1..98a0586 100644
--- a/data/ui/mainmenubutton.ui
+++ b/data/ui/mainmenubutton.ui
@@ -132,7 +132,7 @@
     <property name="receives_default">True</property>
     <property name="popup">menu</property>
     <child>
-      <object class="GtkImage" id="image1">
+      <object class="GtkImage" id="open_menu_image">
         <property name="visible">True</property>
         <property name="can_focus">False</property>
         <property name="icon_name">open-menu-symbolic</property>
diff --git a/pitivi/mainwindow.py b/pitivi/mainwindow.py
index 07e3ba8..dd0972b 100644
--- a/pitivi/mainwindow.py
+++ b/pitivi/mainwindow.py
@@ -238,6 +238,11 @@ class PitiviMainWindow(Gtk.ApplicationWindow, Loggable):
         builder.add_from_file(os.path.join(get_ui_dir(), "mainmenubutton.ui"))
         builder.connect_signals(self)
         self._menubutton = builder.get_object("menubutton")
+
+        if Gtk.get_major_version() == 3 and Gtk.get_minor_version() < 13:
+            open_menu_image = builder.get_object("open_menu_image")
+            open_menu_image.set_property("icon_name", "emblem-system-symbolic")
+
         self._menubutton_items = {}
         for widget in builder.get_object("menu").get_children():
             self._menubutton_items[Gtk.Buildable.get_name(widget)] = widget