[pitivi] timeline: fix missing import

[Jean-François Fortin Tam <jfft src gnome org>]

commit 73515dcd0e6a57ed8877414e3aca8aad058b0245
Author: Lubosz Sarnecki <lubosz gmail com>
Date:   Tue Apr 9 18:34:15 2013 +0200

    timeline: fix missing import
    
    fix following exception:
    
    Traceback (most recent call last):
      File "/usr/lib/pitivi/python/pitivi/timeline/timeline.py", line 1197,
    in _dragLeaveCb
        GLib.timeout_add(75, self._dragCleanUp, context)
    NameError: global name 'GLib' is not defined

 pitivi/timeline/timeline.py |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/pitivi/timeline/timeline.py b/pitivi/timeline/timeline.py
index 93df502..4bdbb91 100644
--- a/pitivi/timeline/timeline.py
+++ b/pitivi/timeline/timeline.py
@@ -34,6 +34,7 @@ from gi.repository import GObject
 from gi.repository import GooCanvas
 
 from gi.repository import Gdk
+from gi.repository import GLib
 
 from gettext import gettext as _
 from os.path import join