Tkinter, step 2: adapt imports.
diff --git a/Lib/idlelib/TreeWidget.py b/Lib/idlelib/TreeWidget.py
index 04e16a2..d4e524b 100644
--- a/Lib/idlelib/TreeWidget.py
+++ b/Lib/idlelib/TreeWidget.py
@@ -15,7 +15,7 @@
 # - optimize tree redraw after expand of subnode
 
 import os
-from Tkinter import *
+from tkinter import *
 import imp
 
 from idlelib import ZoomHeight