How will be correct open new window from imported script (tkinter, python)?

Widget tk.Entry from example_script.py do not save value 'textvariable' field.

example_script.py:

import Tkinter as tk

class App(tk.Frame):
    def __init__(self, master, text):
        tk.Frame.__init__(self, master)
        textVar = tk.StringVar()
        textVar.set(text)
        entryVar = tk.Entry(self, textvariable=textVar).pack()
        self.pack()

def main():
    root = tk.Tk()
    text = ['text1', 'text2', 'text3']
    for i in text:
        App(root, i)
    root.mainloop()

main_script.py:

import Tkinter import example_script as ex

if __name__ == '__main__':
    root = Tkinter.Tk()
    Tkinter.Button(root, text='press', command=lambda: ex.main()).pack()
    root.mainloop()

If I change row 'entryVar = tk.Entry(self, textvariable=textVar).pack()' to

entryVar = tk.Entry(self)
entryVar.pack()
entryVar.insert(0, text)

field's value is updated. Why?

How will be correct open new window from imported script? Tkinter.Toplevel() is not suitable. Now I use subprocess.Popen.