fix a lot of Tkinter imports
diff --git a/Demo/tkinter/matt/packer-and-placer-together.py b/Demo/tkinter/matt/packer-and-placer-together.py
index 84d3ee0..3cf6c45 100644
--- a/Demo/tkinter/matt/packer-and-placer-together.py
+++ b/Demo/tkinter/matt/packer-and-placer-together.py
@@ -1,4 +1,4 @@
-from Tkinter import *
+from tkinter import *
 
 # This is a program that tests the placer geom manager in conjunction with
 # the packer. The background (green) is packed, while the widget inside is placed