[orca] Add a default listener for children-changed events

[Joanmarie Diggs <joanied src gnome org>]

commit 12f5641e9c2fe113fcb4022b9eab7957dc4615c1
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Tue Oct 29 15:30:09 2013 -0400

    Add a default listener for children-changed events

 src/orca/scripts/default.py |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/src/orca/scripts/default.py b/src/orca/scripts/default.py
index b4ac17b..0734505 100644
--- a/src/orca/scripts/default.py
+++ b/src/orca/scripts/default.py
@@ -525,6 +525,8 @@ class Script(script.Script):
             self.onTextInserted
         listeners["object:active-descendant-changed"]       = \
             self.onActiveDescendantChanged
+        listeners["object:children-changed"]                = \
+            self.onChildrenChanged
         listeners["object:link-selected"]                   = \
             self.onLinkSelected
         listeners["object:state-changed:active"]            = \
@@ -2255,6 +2257,14 @@ class Script(script.Script):
                 [orca_state.locusOfFocus.parent,
                  orca_state.locusOfFocus.getIndexInParent()]
 
+    def onChildrenChanged(self, event):
+        """Called when a child node has changed.
+
+        Arguments:
+        - event: the Event
+        """
+        pass
+
     def onCaretMoved(self, event):
         """Called whenever the caret moves.