By using a gui designer (glade-2, gazpacho, etc)
        widgets can have a prefix in theirs names
        like foo:entry1 or foo:label3
        It means entry1 and label3 has a prefix action named foo.

        Then, prefix_actions_proxy must have a method named prefix_foo which
        is called everytime a widget with prefix foo is found, using the found widget
        as argument.

        prefix_actions_proxy:
            An instance with methods as prefix actions.
            It means it has methods like prefix_foo, prefix_bar, etc.

def add_prefix_actions(self, prefix_actions_proxy):
        """
        By using a gui designer (glade-2, gazpacho, etc)
        widgets can have a prefix in theirs names
        like foo:entry1 or foo:label3
        It means entry1 and label3 has a prefix action named foo.

        Then, prefix_actions_proxy must have a method named prefix_foo which
        is called everytime a widget with prefix foo is found, using the found widget
        as argument.

        prefix_actions_proxy:
            An instance with methods as prefix actions.
            It means it has methods like prefix_foo, prefix_bar, etc.
        """
        prefix_s = "prefix_"
        prefix_pos = len(prefix_s)

        def is_method(t):
            return callable(t[1])

        def is_prefix_action(t):
            return t[0].startswith(prefix_s)

        def drop_prefix(k, w):
            return (k[prefix_pos:], w)

        members_t = inspect.getmembers(prefix_actions_proxy)
        methods_t = filter(is_method, members_t)
        prefix_actions_t = filter(is_prefix_action, methods_t)
        prefix_actions_d = dict(map(drop_prefix, prefix_actions_t))

        for widget in self.get_widgets():
            prefixes = gtk.Widget.get_data(widget, "prefixes")
            if prefixes:
                for prefix in prefixes:
                    if prefix in prefix_actions_d:
                        prefix_action = prefix_actions_d[prefix]
                        prefix_action(widget)