[Tutor] Copy file as root

[Timo]

Hello, I'm writing a program in Python/pyGTK and I need to be root 2
times. The first time is to open a file, let's say menu.lst. I use
os.system('gksudo gedit /boot/grub/menu.lst'), so that works. But what
if I have a copy of the file on my desktop? I use shutil.copyfile() to
copy the file from /boot/grub/ to /home/user/Desktop, but ofcourse need
to be root to copy it back.
So, how can I use shutil.copyfile() with gksudo to ask the password? Or
is the another good way to do this in Python?

Greets,
Timo