Code below has 1 major and 1 minor problem. Major issue is, once you push the button it visually stays pushed. Minor problem is, I run this in Cygwin. I've got an rxvt window behind the Tk window.

Tkinter is widely used to build GUIs in Python due to its simplicity. In this book, you’ll discover Tkinter’s strengths and overcome its challenges as you learn to develop fully featured GUI ...