    def test_multi_column_list_box_scrollbar(self):
        """
        Check MultiColumnListBox scrollbar works.
        """
        # Create a dummy screen.
        screen = MagicMock(spec=Screen, colours=8, unicode_aware=False)
        scene = Scene([], -1)
        canvas = Canvas(screen, 10, 40, 0, 0)

        # Create the form we want to test.
        form = Frame(canvas, canvas.height, canvas.width, has_border=False, can_scroll=False)
        layout = Layout([100], fill_frame=True)
        mc_list = MultiColumnListBox(
            3,
            [3, 0, ">4"],
            [
                (["1", "2", "3"], 1),
                (["11", "222", "333"], 2),
                (["111", "2", "3"], 3),
            ],
            titles=["A", "B", "C"],
            add_scroll_bar=True,
            name="mc_list")
        form.add_layout(layout)
        layout.add_widget(mc_list)
        form.fix()
        scene.add_effect(form)
        form.reset()

        # Check that the widget is rendered correctly with the scrollbar
        form.update(0)
        self.assert_canvas_equals(
            canvas,
            "A  B                                  C \n" +
            "1  2                                  3O\n" +
            "11 222                              333|\n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n")

        # Check that search works
        self.process_keys(form, ["111"])
        form.update(0)
        self.assert_canvas_equals(
            canvas,
            "A  B                                  C \n" +
            "11 222                              333O\n" +
            "1112                                  3|\n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n" +
            "                                        \n")
Check MultiColumnListBox scrollbar works.
tests/test_widgets.py