How to set focus for Tkinter widget?

Question

I have a simple Python + Tkinter application that displays a list of 10 items:

import Tkinter, ttk
list = ttk.Treeview( Tkinter.Tk() )
list.pack( fill = Tkinter.BOTH, expand = 1 )
items = [ list.insert( '', 'end', text = str( i ) ) for i in range( 10 ) ]
list.selection_set( items[ 0 ] )
list.focus_set() # This is not working - list has no focus :(
Tkinter.mainloop()

Is it possible to modify it so after application starts, list will have focus and i can move selection via up and down arrows? After app starts, app's window has focus, but i can't move selection with arrows until i click list with mouse :(. I tried different combinations of focus_set() and focus_force(), but it's not working.

Checked with Python 2.7 on Windows 7, OSX 10.7 and Ubuntu 12.04

UPDATE

If "Treeview" is changed to some other widget, for example to "Button", the focus is working. So it's seems that i set focus for Treeview somehow incorrectly.

Answer 1

Found a solution at last - seems that Treeview widget need to be set focus two times: first for the widget itself, and second for an item:

list.selection_set( items[ 0 ] )
list.focus_set()
list.focus( items[ 0 ] ) # this fixes a problem.