fix a lot of Tkinter imports
diff --git a/Demo/tkinter/matt/subclass-existing-widgets.py b/Demo/tkinter/matt/subclass-existing-widgets.py
index fc04859..ce97f35 100644
--- a/Demo/tkinter/matt/subclass-existing-widgets.py
+++ b/Demo/tkinter/matt/subclass-existing-widgets.py
@@ -1,4 +1,4 @@
-from Tkinter import *
+from tkinter import *
 
 # This is a program that makes a simple two button application