import sys
from Tkinter import Toplevel, Button, Label
win1 = Toplevel() # two independent windows
win2 = Toplevel() # but part of same process
Button(win1, text='Spam', command=sys.exit).pack()
Button(win2, text='SPAM', command=sys.exit).pack()
Label(text='Popups').pack() # on default Tk() root window
win1.mainloop()