Fix gtk example against py3k
Fix gtk example against py3k

Signed-off-by: Olivier Aubert <1a73af9e7ae00182733b2292511b814be66f065f@olivieraubert.net>

oaubert/python-vlc,oaubert/python-vlc,pombreda/git.videolan.org-vlc-bindings-python,pombreda/git.videolan.org-vlc-bindings-python