gonzalo@gaf1~/progs/python/test2$ python test2.py 
sys:1: DeprecationWarning: Non-ASCII character '\xc3' in file test2.py on line 2, but no encoding declared; see http://www.python.org/peps/pep-0263.html for details
Traceback (most recent call last):
  File "test2.py", line 30, in ?
    Gui()
  File "test2.py", line 11, in __init__
    signals = {
AttributeError: Gui instance has no attribute 'on_button1_clicked'