How to use the pympress.extras.Cursor.set_cursor function in pympress

self.show_pointer = False
        for slide_widget in [self.p_da_cur, self.c_da]:
            ww, wh = slide_widget.get_allocated_width(), slide_widget.get_allocated_height()
            if max(ww, wh) == 1:
                continue

            pointer_coordinates = slide_widget.get_window().get_pointer()

            if 0 < pointer_coordinates.x < ww and 0 < pointer_coordinates.y < wh \
                    and self.pointer_mode == PointerMode.CONTINUOUS:
                # Laser activated right away
                self.pointer_pos = (pointer_coordinates.x / ww, pointer_coordinates.y / wh)
                self.show_pointer = True
                extras.Cursor.set_cursor(slide_widget, 'invisible')
            else:
                extras.Cursor.set_cursor(slide_widget, 'parent')

        self.redraw_current_slide()

It is switched on again when the mouse reenters the slide.

        Args:
            widget (:class:`~Gtk.Widget`):  the widget which has received the event.
            event (:class:`~Gdk.Event`):  the GTK event.

        Returns:
            `bool`: whether the event was consumed
        """
        # Only handle enter/leave events on one of the current slides
        if self.pointer_mode != PointerMode.CONTINUOUS or widget not in [self.c_da, self.p_da_cur]:
            return False

        if event.type == Gdk.EventType.ENTER_NOTIFY:
            self.show_pointer = True
            extras.Cursor.set_cursor(widget, 'invisible')

        elif event.type == Gdk.EventType.LEAVE_NOTIFY:
            self.show_pointer = False
            extras.Cursor.set_cursor(widget, 'parent')

        self.redraw_current_slide()
        return True

if event.type != Gdk.EventType.MOTION_NOTIFY:
            return False

        # Where did the event occur?
        if widget is self.p_da_next:
            page = self.doc.next_page()
            if page is None:
                return
        else:
            page = self.doc.current_page()

        x, y = self.zoom.get_slide_point(widget, event)
        page_mode = self.notes_mode if widget is self.p_da_notes else self.notes_mode.complement()

        if page.get_link_at(x, y, page_mode):
            extras.Cursor.set_cursor(widget, 'pointer')
            return False
        else:
            extras.Cursor.set_cursor(widget, 'parent')
            return True

Args:
            widget (:class:`~Gtk.Widget`):  the widget which has received the event.
            event (:class:`~Gdk.Event`):  the GTK event.

        Returns:
            `bool`: whether the event was consumed
        """
        if self.pointer_mode in {PointerMode.DISABLED, PointerMode.CONTINUOUS}:
            return False

        ctrl_pressed = event.get_state() & Gdk.ModifierType.CONTROL_MASK

        if ctrl_pressed and event.type == Gdk.EventType.BUTTON_PRESS:
            self.show_pointer = True
            extras.Cursor.set_cursor(widget, 'invisible')

            # Immediately place & draw the pointer
            return self.track_pointer(widget, event)

        elif self.show_pointer and event.type == Gdk.EventType.BUTTON_RELEASE:
            self.show_pointer = False
            extras.Cursor.set_cursor(widget, 'parent')
            self.redraw_current_slide()
            return True

        else:
            return False