[orca] Attempt to weed out object:selection-changed events from dead accessibles

[Joanmarie Diggs <joanied src gnome org>]

commit 51164a3ce4bd2a2c87050c0a0178283bed0ed171
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Sat Apr 28 19:49:04 2018 -0400

    Attempt to weed out object:selection-changed events from dead accessibles

 src/orca/event_manager.py |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/src/orca/event_manager.py b/src/orca/event_manager.py
index 66c7d62..f26f4fa 100644
--- a/src/orca/event_manager.py
+++ b/src/orca/event_manager.py
@@ -203,6 +203,13 @@ class EventManager:
                 debug.println(debug.LEVEL_INFO, msg, True)
                 return True
 
+            try:
+                _name = event.source.name
+            except:
+                msg = 'EVENT MANAGER: Ignoring event from dead source'
+                debug.println(debug.LEVEL_INFO, msg, True)
+                return True
+
         if event.type.startswith('object:children-changed:add') \
            or event.type.startswith('object:active-descendant-changed'):
             if role in [pyatspi.ROLE_MENU,