[python-win32] How to detect User presseing escape, or clicking cancel in call to win32gui.GetOpenFileNameW()

[Tony Cappellini]

I'm trying to understand how to detect a user pressing Escape, or
clicking on Cancel when
win32gui.GetOpenFileNameW() is called.

When I press escape when the FileOpen dialogue is present, I see the
following error with Python2.5/PWin32 Build 210

error: (0, 'GetOpenFileNameW', 'No error message is available')

Would someone explain what this means, or how to detect the above situatiions?