the second of nested buttons using textvariable remains void!

[Samkos]

Hi there,

I am fighting with a problem I intended to  believe trivial that
I could not solve yet!

I am trying to have a button with a variable text, that
pops up another button with a variable text when pressed.

I did that with the following program  in Python, but the
second button remains always void!!! is it related to
the textvariable parameters?

If any of you had a clue, please  don't hesitate!

in advance, many thanks

Samuel

#----------------------- program 2 buttons.py
--------------------------

from Tkinter import *


def go(event):
    root = Tk()

    s1=StringVar()
    s1.set("s1")
    label1 = Label(root, textvariable=s1)
    label1.pack(side=LEFT)

    root.mainloop()



root = Tk()

s0=StringVar()
s0.set("s0")
label0 = Label(root, textvariable=s0)
label0.pack(side=LEFT)


root.bind("<Return>",go)

root.mainloop()