[pitivi] widgets: Check that effect has a parent to hide related effects keyframe

[Thibault Saunier <tsaunier src gnome org>]

commit 94a35e987a22c8458efbf1758938710aaa48232d
Author: Thibault Saunier <tsaunier gnome org>
Date:   Sat Nov 15 17:23:10 2014 +0100

    widgets: Check that effect has a parent to hide related effects keyframe
    
    Avoiding backtrace when undo an effect adition while editing that
    effect properties

 pitivi/utils/widgets.py |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/pitivi/utils/widgets.py b/pitivi/utils/widgets.py
index a931668..157e38c 100644
--- a/pitivi/utils/widgets.py
+++ b/pitivi/utils/widgets.py
@@ -610,7 +610,12 @@ class GstElementSettingsWidget(Gtk.VBox, Loggable):
                 self._setKeyframeToggleButtonState(togglebutton, False)
 
         effect = self.element
-        for track_element in effect.get_parent().get_children(False):
+        parent = effect.get_parent()
+        if not parent:
+            self.log("Effect has no parent (it has been removed?)")
+            return
+
+        for track_element in parent.get_children(False):
             if hasattr(track_element, "ui_element"):
                 track_element.ui_element.hideKeyframes()