Почему мой код меню сообщений не работает при разделении на функции?

Ниже приведены две программы на Python. Они абсолютно одинаковые, за исключением того, что одна разделена на две функции. Однако не работает только та, которая разделена на две функции - вторая не работает. Почему это так?

Обратите внимание, код взят из этого полезного поста в блоге .

Без функций (работает):

import gtk

def show_window_function(x, y):
    print x
    print y

# get the indicate module, which does all the work
import indicate

# Create a server item
mm = indicate.indicate_server_ref_default()
# If someone clicks your server item in the MM, fire the server-display signal
mm.connect("server-display", show_window_function)
# Set the type of messages that your item uses. It's not at all clear which types
# you're allowed to use, here.
mm.set_type("message.im")
# You must specify a .desktop file: this is where the MM gets the name of your
# app from.
mm.set_desktop_file("/usr/share/applications/nautilus.desktop")
# Show the item in the MM.
mm.show()

# Create a source item
mm_source = indicate.Indicator()
# Again, it's not clear which subtypes you are allowed to use here.
mm_source.set_property("subtype", "im")
# "Sender" is the text that appears in the source item in the MM
mm_source.set_property("sender", "Unread")
# If someone clicks this source item in the MM, fire the user-display signal
mm_source.connect("user-display", show_window_function)
# Light up the messaging menu so that people know something has changed
mm_source.set_property("draw-attention", "true")
# Set the count of messages in this source.
mm_source.set_property("count", "15")
# If you prefer, you can set the time of the last message from this source,
# rather than the count. (You can't set both.) This means that instead of a
# message count, the MM will show "2m" or similar for the time since this
# message arrived.
# mm_source.set_property_time("time", time.time())
mm_source.show()

gtk.mainloop()

С функциями (вторая функция выполняется, но фактически не работает):

import gtk

def show_window_function(x, y):
    print x
    print y

# get the indicate module, which does all the work
import indicate

def function1():
    # Create a server item
    mm = indicate.indicate_server_ref_default()
    # If someone clicks your server item in the MM, fire the server-display signal
    mm.connect("server-display", show_window_function)
    # Set the type of messages that your item uses. It's not at all clear which types
    # you're allowed to use, here.
    mm.set_type("message.im")
    # You must specify a .desktop file: this is where the MM gets the name of your
    # app from.
    mm.set_desktop_file("/usr/share/applications/nautilus.desktop")
    # Show the item in the MM.
    mm.show()

def function2():
    # Create a source item
    mm_source = indicate.Indicator()
    # Again, it's not clear which subtypes you are allowed to use here.
    mm_source.set_property("subtype", "im")
    # "Sender" is the text that appears in the source item in the MM
    mm_source.set_property("sender", "Unread")
    # If someone clicks this source item in the MM, fire the user-display signal
    mm_source.connect("user-display", show_window_function)
    # Light up the messaging menu so that people know something has changed
    mm_source.set_property("draw-attention", "true")
    # Set the count of messages in this source.
    mm_source.set_property("count", "15")
    # If you prefer, you can set the time of the last message from this source,
    # rather than the count. (You can't set both.) This means that instead of a
    # message count, the MM will show "2m" or similar for the time since this
    # message arrived.
    # mm_source.set_property_time("time", time.time())
    mm_source.show()

function1()
function2()
gtk.mainloop()