def _create_widgets(self):
        """
        This function fills this box with widgets
        """
        # Division of the available space in three segments:
        # top, middle and bottom (parameters_ui)
        top = Gtk.Box()
        top.set_spacing(6)
        middle = Gtk.Box()
        middle.set_spacing(6)
        self._fill_top_box(top)
        self._fill_middle_box(middle)
        self.pack_start(top, False, True, 0)
        self.pack_start(middle, False, True, 0)
        align = Gtk.Alignment.new(0, 0, 1, 0)
        align.set_padding(10, 0, 0, 0)
        self.parameters_ui = ParametersUI(self.req)
        align.add(self.parameters_ui)
        self.pack_start(align, False, True, 0)