fix a lot of Tkinter imports
diff --git a/Demo/tkinter/matt/killing-window-w-wm.py b/Demo/tkinter/matt/killing-window-w-wm.py
index 23ac103..b4034d1 100644
--- a/Demo/tkinter/matt/killing-window-w-wm.py
+++ b/Demo/tkinter/matt/killing-window-w-wm.py
@@ -1,4 +1,4 @@
-from Tkinter import *
+from tkinter import *
 
 # This file shows how to trap the killing of a window
 # when the user uses window manager menus (typ. upper left hand corner