With 3.2, (Winxp) I get combobox with first line,
input as
r'C:\Python31\Lib\tkinter\test\test_ttk',
displayed as
"C:Python31Lib	kinter	est	est_ttk"
Something either deleted \ or converted \t to tab.
Indeed, adding a space to the end of the string or enclosing as you specify inhibits deletion/conversion, so this seems like an error.

With imports fixed
from Tkinter import *
import ttk
the file runs fine in 2.7, so this seems 3.x specific problem.