Tkinter, resize window, keep widgets relative placements?

[skanemupp at yahoo.se]

the code is down below. when i click maximize window it looks terrible
since the widgets are not keeping their relative size.
i guess i could use pack or grid to do that instead of place?
but i tried with pack and grid before and had trouble making it
looking good.

is it possible to have the minimized window just being placed in the
middle without the distance between the buttons and entrys being
enlonge>?


from __future__ import division
import Tkinter
from Tkinter import *

mygui = Tkinter.Tk()

mygui.title("Calculator")

l = Label(mygui, text="Answer: ")
l.place(relx=0.15, rely=0.2, anchor=CENTER)

e = Entry(mygui)
e.place(relx=0.48, rely=0.1, anchor=CENTER, width=173)

c = Entry(mygui)
c.place(relx=0.6, rely=0.2, anchor=CENTER)

def Disp(nstr):
    e.insert(INSERT, nstr)

def Calc():
    expr=e.get()
    c.delete(0, END)
    try:
        c.insert(END, eval(expr))
    except:
        c.insert(END, "Not computable")

def Erase():
    e.delete(0,END)
    c.delete(0, END)

def Backspace():
    a=len(e.get())
    e.delete(a-1,END)
    #e.delete(INSERT, END)
    #e.delete(ANCHOR,END)


x = 0.1
y = 0.4
for char in '123+456-789*0()/.':
    b = Button(mygui, text=char, command=lambda n=char:Disp(n),
width=2, height=1)
    b.place(relx=x, rely=y, anchor=CENTER)
    x=x+0.1
    if x==0.5:
        x=0.1
        y=y+0.1

b = Button(mygui, text="^", command=lambda n="**":Disp(n), width=2,
height=1)
b.place(relx=0.2, rely=0.8, anchor=CENTER)
b = Button(mygui, text="C",command=Erase, width=2, height=1)
b.place(relx=0.3, rely=0.8, anchor=CENTER)
b = Button(mygui, text="c",command=Backspace, width=2, height=1)
b.place(relx=0.4, rely=0.8, anchor=CENTER)
b = Button(mygui, text="=",command=Calc, width=12, height=1)
b.place(relx=0.25, rely=0.9, anchor=CENTER)

mygui.mainloop()