diff --git a/Lib/sched.py b/Lib/sched.py
index 6c01e69..3e41198 100644
--- a/Lib/sched.py
+++ b/Lib/sched.py
@@ -35,6 +35,9 @@
 __all__ = ["scheduler"]
 
 class Event(namedtuple('Event', 'time, priority, action, argument, kwargs')):
+    def __init__(self, *args, **kwargs):
+        super(Event, self).__init__(*args, **kwargs)
+        self._scheduled = False
     def __eq__(s, o): return (s.time, s.priority) == (o.time, o.priority)
     def __ne__(s, o): return (s.time, s.priority) != (o.time, o.priority)
     def __lt__(s, o): return (s.time, s.priority) <  (o.time, o.priority)
@@ -59,6 +62,7 @@
 
         """
         event = Event(time, priority, action, argument, kwargs)
+        event._scheduled = True
         heapq.heappush(self._queue, event)
         return event # The ID
 
@@ -81,6 +85,9 @@
         self._queue.remove(event)
         heapq.heapify(self._queue)
 
+    def is_scheduled(self, event):
+        return event._scheduled
+
     def empty(self):
         """Check whether the queue is empty."""
         return not self._queue
@@ -122,6 +129,7 @@
                 # Verify that the event was not removed or altered
                 # by another thread after we last looked at q[0].
                 if event is checked_event:
+                    event._scheduled = False
                     action(*argument, **kwargs)
                     delayfunc(0)   # Let other threads run
                 else:
diff --git a/Misc/ACKS b/Misc/ACKS
index fe2af75..cecb238 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -11,7 +11,6 @@
 PS: In the standard Python distribution, this file is encoded in UTF-8
 and the list is in rough alphabetical order by last names.
 
-Chris Clark
 Rajiv Abraham
 David Abrahams
 Ron Adam
@@ -179,6 +178,7 @@
 Vadim Chugunov
 David Cinege
 Craig Citro
+Chris Clark
 Mike Clarkson
 Andrew Clegg
 Brad Clements