fix a lot of Tkinter imports
diff --git a/Demo/tkinter/matt/canvas-demo-simple.py b/Demo/tkinter/matt/canvas-demo-simple.py
index b677ccd..7f2c17b 100644
--- a/Demo/tkinter/matt/canvas-demo-simple.py
+++ b/Demo/tkinter/matt/canvas-demo-simple.py
@@ -1,4 +1,4 @@
-from Tkinter import *
+from tkinter import *
 
 # this program creates a canvas and puts a single polygon on the canvas