diff -r c08e92529f62 Lib/idlelib/AutoComplete.py
--- a/Lib/idlelib/AutoComplete.py	Sun Sep 08 20:42:13 2013 +0300
+++ b/Lib/idlelib/AutoComplete.py	Mon Sep 09 21:39:31 2013 +0300
@@ -160,12 +160,12 @@
         if not comp_lists[0]:
             return
         self.autocompletewindow = self._make_autocomplete_window()
-        self.autocompletewindow.show_window(comp_lists,
+        return not self.autocompletewindow.show_window(
+                                            comp_lists,
                                             "insert-%dc" % len(comp_start),
                                             complete,
                                             mode,
                                             userWantsWin)
-        return True
 
     def fetch_completions(self, what, mode):
         """Return a pair of lists of completions for something. The first list
diff -r c08e92529f62 Lib/idlelib/AutoCompleteWindow.py
--- a/Lib/idlelib/AutoCompleteWindow.py	Sun Sep 08 20:42:13 2013 +0300
+++ b/Lib/idlelib/AutoCompleteWindow.py	Mon Sep 09 21:39:31 2013 +0300
@@ -157,13 +157,14 @@
         self.start = self.widget.get(self.startindex, "insert")
         if complete:
             completed = self._complete_string(self.start)
+            start = self.start
             self._change_start(completed)
             i = self._binary_search(completed)
             if self.completions[i] == completed and \
                (i == len(self.completions)-1 or
                 self.completions[i+1][:len(completed)] != completed):
                 # There is exactly one matching completion
-                return
+                return completed == start
         self.userwantswindow = userWantsWin
         self.lasttypedstart = self.start