Finally fix SF bug #441172, using a variant of patch ##443626:

gvanrossum · gvanrossum · commit 38507ae614b2 · 2001-08-11T04:37:07.000Z
canceling an edit operation would not revert the value of the field.
The fix takes care to destroy the Entry object, as suggested in the
patch.
diff --git a/Tools/idle/TreeWidget.py b/Tools/idle/TreeWidget.py
@@ -291,6 +291,12 @@ def edit_finish(self, event=None):
         self.canvas.focus_set()
 
     def edit_cancel(self, event=None):
+        try:
+            entry = self.entry
+            del self.entry
+        except AttributeError:
+            return
+        entry.destroy()
         self.drawtext()
         self.canvas.focus_set()
 
