Index: accessible.py
===================================================================
--- accessible.py	(revision 1018)
+++ accessible.py	(working copy)
@@ -115,6 +115,13 @@
   @param event: One of the L{constants.CACHE_EVENTS} event types
   @type event: L{event.Event}
   '''
+  if event.type == "object:property-change:accessible-parent":
+    # Get rid of the cached parent first.
+    try:
+      _ACCESSIBLE_CACHE[hash(event.source.parent)].wipe()
+    except KeyError:
+      pass
+
   try:
     _ACCESSIBLE_CACHE[hash(event.source)].wipe()
   except KeyError:
