问如何在一个平纹窗口中间保持“适合孩子”的行为？

EN

from Tkinter import *
import ttk

def center(root):
    w = root.winfo_screenwidth()
    h = root.winfo_screenheight()
    rootsize = tuple(int(_) for _ in root.geometry().split('+')[0].split('x'))
    x = w/2 - rootsize[0]/2
    y = h/2 - rootsize[1]/2
    root.geometry("%dx%d+%d+%d" % (rootsize + (x, y)))

root = Tk()
var = StringVar()
var.set('Small Text')

label = ttk.Label(root, textvariable=var)
label.grid(column=0, row=0)

# Change the text label in a couple of seconds.
def changeit():
    var.set('BIG TXT - ' * 5)
root.after(2000, changeit)

# Comment out this center call and the label expands.
root.after(100, lambda: center(root))
root.mainloop()