Example fixes

- replaced Gtk.HBox/Gtk.VBox by GtkBox as seen in [1] and [2]
GtkHbox and GtkVBox are deprecated
- use delete-event instead of destroy event in GtkWindow
- replaced icon_size for pixel_size where used
it's also deprecated as seen in commit [3]
- use sugar_theme in all examples; set it manually not by just
importing common module
- fixed GtkBox.pack_start arguments
- flake/pep8 fixes

[1] https://developer.gnome.org/gtk3/stable/GtkHBox.html
[2] https://developer.gnome.org/gtk3/stable/GtkVBox.html
[3] 5802d67ee1

examples/scrollingdetector.py

@@ -29,7 +29,7 @@ model = Gtk.ListStore(str)
 data_dir = os.getenv('GTK_DATA_PREFIX', '/usr/')
 
 iconlist = os.listdir(os.path.join(data_dir,
-                      'share/icons/sugar/scalable/actions/'))
+                                   'share/icons/sugar/scalable/actions/'))
 print "Displaying %s icons" % len(iconlist)
 for icon in iconlist:
     icon = os.path.basename(icon)