fix a lot of Tkinter imports
diff --git a/Demo/tkinter/guido/hello.py b/Demo/tkinter/guido/hello.py
index 358a7ec..f10fb7a 100755
--- a/Demo/tkinter/guido/hello.py
+++ b/Demo/tkinter/guido/hello.py
@@ -1,7 +1,7 @@
 # Display hello, world in a button; clicking it quits the program
 
 import sys
-from Tkinter import *
+from tkinter import *
 
 def main():
     root = Tk()