ttk: how to make a frame look like a labelframe?

Python ttk gui creating is easy and has mostly native look and feel (win7). I am having a slight problem, though:

I would like to have a frame that looks like ttk.LabelFrame but without label. Just omitting the text option will leave an ugly gap.

Also I can not get the ttk.Frame border to look like LabelFrame. Is there an elegant way of doing this? Bonus karma if this works on all/most windows versions above xp.

Maybe it works with styles but the style LabelFrame properties seem mostly empty (style.element_options("border.relief")). Maybe I am looking in the wrong place.

edit:

try:  # python 3
    from tkinter import *  # from ... import * is bad
    from tkinter.ttk import *
except:
    from Tkinter import *
    from ttk import *

t = Tcl().eval
print("tcl version: " + str(t("info patchlevel")))
print("TkVersion: " + str(TkVersion))

root = Tk()

lF = LabelFrame(root, text=None)
lF.grid()
b = Button(lF, text='gonzo')
b.grid()

f = Frame(root, relief="groove") #GROOVE)
f.grid()
b2 = Button(f, text='gonzo')
b2.grid()

f2 = Frame(root, relief=GROOVE, borderwidth=2)
f2.grid()
b3 = Button(f2, text='gonzo')
b3.grid()

mainloop()

output on win7 with freshly downloaded python 3.2.3:

tcl version: 8.5.9

TkVersion: 8.5

There is python 2.6.6 installed on this machine, too (same problem). Each installation seems to be using the correct tk/tcl, though.

OK, seems like one solution to getting the LabelFrame without the gap is to use an empty widget in place of the text. So, modifying the first part of your example slightly:

# don't do the 'from tkinter import *' thing to avoid namespace clashes
import tkinter   # assuming Python 3 for simplicity's sake
import tkinter.ttk as ttk 

root = tkinter.Tk()

f = tkinter.Frame(relief='flat')
lF = ttk.LabelFrame(root, labelwidget=f, borderwidth=4)
lF.grid()
b = ttk.Button(lF, text='gonzo')
b.grid()

root.mainloop()

Seems to work for me with the regular Win7 theme.