[FIX] Win32 UI: Ignore fileno if not supported

On some environments, like IDLE, getting the fileno of a std stream
raises an UnsupportedOperation error.

See also:
https://mail.python.org/pipermail/python-list/2014-November/693894.html

Change-Id: Idf934258e704176f788d68ecfa7edad9a3066f6d