here is a good explanation of control vars: http://infohost.nmt.edu/tcc/help/pubs/tkinter/control-variables.html Here are 3 great Tkinter refernces in order: http://infohost.nmt.edu/tcc/help/pubs/tkinter/ http://effbot.org/tkinterbook/ http://www.pythonware.com/library/tkinter/introduction/