--- On Sun, 3/20/11, Daniel Welling <dantwelling@gmail.com> wrote:
> The OSX backend used to have a bug where you cannot type a
> name in the file name text box.Since that has been fixed, ...
That was not a bug in the MacOSX backend (and therefore was not fixed), but is related to how Python is installed on your system: If your Python is not a framework installation, it will not interact correctly with Apple's windowing manager. This is due to OS X itself and is independent of the MacOSX backend.
I have found a new bug: every so often, when you go to save a file, the "save" and "cancel" button stop responding, trapping the user in file saving limbo.  I'll have to play with it again to figure out what triggers this.
Can you check if your Python is built as a framework? If it is, MacOS.WMAvailable() should return True:

$ python
Python 2.7.1 (r271:86832, Mar 12 2011, 13:44:53)
[GCC 4.0.1 (Apple Computer, Inc. build 5370)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import MacOS
>>> MacOS.WMAvailable()