fix a lot of Tkinter imports
diff --git a/Demo/tkinter/matt/radiobutton-simple.py b/Demo/tkinter/matt/radiobutton-simple.py
index eeddb23..a2719b8 100644
--- a/Demo/tkinter/matt/radiobutton-simple.py
+++ b/Demo/tkinter/matt/radiobutton-simple.py
@@ -1,4 +1,4 @@
-from Tkinter import *
+from tkinter import *
 
 # This is a demo program that shows how to
 # create radio buttons and how to get other widgets to