M EditorWindow.py
M IOBinding.py
M NEWS.txt
M configDialog.py

- If nulls somehow got into the strings in recent-files.lst
  EditorWindow.update_recent_files_list() was failing.  Python Bug 931336.
diff --git a/Lib/idlelib/configDialog.py b/Lib/idlelib/configDialog.py
index 69cf818..2645943 100644
--- a/Lib/idlelib/configDialog.py
+++ b/Lib/idlelib/configDialog.py
@@ -1157,7 +1157,7 @@
         #update theme and repaint
         #update keybindings and re-bind
         #update user help sources menu
-        winInstances=self.parent.instanceDict.keys()
+        winInstances=self.parent.instance_dict.keys()
         for instance in winInstances:
             instance.ResetColorizer()
             instance.ResetFont()
@@ -1183,5 +1183,5 @@
     root=Tk()
     Button(root,text='Dialog',
             command=lambda:ConfigDialog(root,'Settings')).pack()
-    root.instanceDict={}
+    root.instance_dict={}
     root.mainloop()