[pitivi] medialibrary: Fix detection of ctrl/shift pressed

[Alexandru Băluț <alexbalut src gnome org>]

commit c041b55c3833ac1c3a19c86c1e3040fcb9b8402a
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Thu Apr 14 17:05:43 2016 +0200

    medialibrary: Fix detection of ctrl/shift pressed
    
    Seems the change has been made recently by accident.
    
    Differential Revision: https://phabricator.freedesktop.org/D908

 pitivi/medialibrary.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/pitivi/medialibrary.py b/pitivi/medialibrary.py
index fc43acd..5672359 100644
--- a/pitivi/medialibrary.py
+++ b/pitivi/medialibrary.py
@@ -1341,7 +1341,7 @@ class MediaLibraryWidget(Gtk.Box, Loggable):
 
     def _treeViewButtonReleaseEventCb(self, treeview, event):
         selection = self.treeview.get_selection()
-        state = selection() & (
+        state = event.get_state() & (
             Gdk.ModifierType.CONTROL_MASK | Gdk.ModifierType.SHIFT_MASK)
         path = self.treeview.get_path_at_pos(event.x, event.y)