Finish set-up by connecting the widget. The model was already
        specified in the constructor.

        *wid* is a widget instance.

        *getter* is a callable. It is passed *wid* and must return its
        current value.

        *setter* is a callable. It is passed *wid* and the current value of
        the model property and must update the widget.

        *signal* is a string naming the signal to connect to on *wid*. When
        it is emitted we update the model.

        *getter*, *setter* and *signal* are optional. Missing values are
        guessed from *wid* using
        :meth:`gtkmvc3.adapters.default.search_adapter_info`. If nothing is
        found this raises :exc:`TypeError`.

        *arg* is an optional value passed to the handler for *signal*. This
        doesn't do anything unless a subclass overrides the handler.

        *update* denotes whether to update the widget from the model
        immediately. Otherwise the widget stays unchanged until the first
        notification.

        *flavour* can be used to select special behaviours about
         the adaptation when twice or more possibilities are
         possibly handled for the same widget type. See
         adapters.default for further information.

def connect_widget(self, wid,
                       getter=None, setter=None,
                       signal=None, arg=None, update=True,
                       flavour=None):

        """
        Finish set-up by connecting the widget. The model was already
        specified in the constructor.

        *wid* is a widget instance.

        *getter* is a callable. It is passed *wid* and must return its
        current value.

        *setter* is a callable. It is passed *wid* and the current value of
        the model property and must update the widget.

        *signal* is a string naming the signal to connect to on *wid*. When
        it is emitted we update the model.

        *getter*, *setter* and *signal* are optional. Missing values are
        guessed from *wid* using
        :meth:`gtkmvc3.adapters.default.search_adapter_info`. If nothing is
        found this raises :exc:`TypeError`.

        *arg* is an optional value passed to the handler for *signal*. This
        doesn't do anything unless a subclass overrides the handler.

        *update* denotes whether to update the widget from the model
        immediately. Otherwise the widget stays unchanged until the first
        notification.

        *flavour* can be used to select special behaviours about
         the adaptation when twice or more possibilities are
         possibly handled for the same widget type. See
         adapters.default for further information.

        """

        if wid in self._wid_info:
            raise ValueError("Widget " + str(wid) + " was already connected")

        wid_type = None

        if None in (getter, setter, signal):
            w = search_adapter_info(wid, flavour)
            if getter is None:
                getter = w[GETTER]
            if setter is None:
                setter = w[SETTER]
                wid_type = w[WIDTYPE]

            if signal is None:
                signal = w[SIGNAL]

        # saves information about the widget
        self._wid_info[wid] = (getter, setter, wid_type)

        # connects the widget
        if signal:
            if arg:
                wid.connect(signal, self._on_wid_changed, arg)
            else:
                wid.connect(signal, self._on_wid_changed)

        self._wid = wid

        # updates the widget:
        if update:
            self.update_widget()