Python2.3 tkFileDialog.askopenfilename returns tuple on Cancel

[Tim Williams]

I just installed Python 2.3 on my Redhat system. When I tried to run
one of my programs that use tkFileDialog.askopenfilename(), I got an
error because it returns a tuple instead of a null string when I
select Cancel.

Python 2.2:

Python 2.2.2 (#3, Jan 21 2003, 08:39:06)
[GCC 2.95.3 20010315 (release)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import tkFileDialog
>>> f=tkFileDialog.askopenfilename()
>>> print f

>>> f
''
>>> type(f)
<type 'str'>


Python 2.3:

Python 2.3 (#1, Aug  4 2003, 10:43:11)
[GCC 3.2 20020903 (Red Hat Linux 8.0 3.2-7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import tkFileDialog
>>> f=tkFileDialog.askopenfilename()
>>> f
()
>>> type(f)
<type 'tuple'>

Both versions return a string when I select an actual file. Sometimes
I want to click 'Cancel' when I want to bring up my GUI anyway and
select the file later.

I got around this by just putting in an 

if not filename: filename='.'

after my call to askopenfilename().

Is this a bug or a feature?

Thanks.