I use Python 3.1 and Tkinter.ttk 8.5 on Ubuntu 9.10.

CODE:----------------------------------------------------

module:FMain.py

from tkinter import ttk
from FSecondWindow import *

class App:
    def __init__(self,master):

        button1 = ttk.Button(master,text='Show
TopLevel',command=lambda:window())
        button1.pack()

master = Tk()
app = App(master)
style = ttk.Style()
style.theme_use('clam')
master.mainloop()

module:FSecondWindow.py

from tkinter import *
from tkinter import ttk

def window():
    t = Toplevel()
    button2 = Button(t,text='Hello').pack()    

CODE EXPLANATION:-------------------------------------------

1. From the main module FMain.py call the window function that is
located in FSecondWindow module and create a toplevel window.

2.I apply a theme called 'clam' to the master window to improve the
appearance of their widgets.

QUERY:--------------------------------------------------

How I can make the toplevel window also take the theme 'clam'?

Thanks in advance.

Regards.

Long answer: As you might be aware, there are 2 widget sets in
tk/tkinter, the "old" one for which classes are directly in the tkinter
module, and the new one that are in the ttk submodule. Only the second
set supports theming, not the first one. Unfortunately, there are a few
widgets that exist only in the first set, and Toplevel is one of those.
So no theming is directly available for toplevels, and you can change
whatever you want via style.theme_use, it won't be reflected on
toplevels.

By the way, as you wrote the code above, it won't be reflected on your
button either, since you used the Button class, which is taken in
tkinter directly, so it is the "old" Button class, not the new one. To
get the new one, use ttk.Button, not Button.

For your toplevel, there is however a simple workaround: Since there is
a Frame widget in the new widget set, you can simply insert such a frame
in your toplevel, make sure it will take the whole space, and then
insert your widgets in this frame rather than in the toplevel directly.
The code for your 'window' function would then become:

def window()
    t = Toplevel()
    frm = ttk.Frame(t)
    frm.pack(fill=BOTH, expand=True)
    button2 = ttk.Button(frm, text='Hello')
    button2.pack()

(Note also that I have put the creation of the button and its packing in
2 lines. You should never do variable = widget.pack(…) since pack does
not return the widget. It always returns None, so doing so won't put
your widget in the variable).

The code above should do what you're after.

Besides style support, what are the advantages of ttk.Frame vs.
Tkinter.Frame?