# -*- coding: utf-8 -*-
import tkMessageBox

def invertcase():
  text = inputbox.get('1.0', 'end')
  text = text.swapcase()
  inputbox.delete('1.0', 'end')
  inputbox.insert(Tkinter.END, text.strip())
  #print text

import Tkinter
top = Tkinter.Tk()

inputbox = Tkinter.Text(top)
inputbox.insert(Tkinter.END, "Input text here",)
inputbox.pack()

reversecasebutton = Tkinter.Button(top, text="Invert Case", command=invertcase)
reversecasebutton.pack(side=Tkinter.BOTTOM)



top.mainloop()