anchors, panel, dfn);
    panel.addEventListener("keydown", trapListener);

    // Hiding the panel releases the trap
    const mo = new MutationObserver(records => {
      const [record] = records;
      const target = /** @type HTMLElement */ (record.target);
      if (target.hidden) {
        panel.removeEventListener("keydown", trapListener);
        mo.disconnect();
      }
    });
    mo.observe(panel, { attributes: true, attributeFilter: ["hidden"] });
  }

  /**
   *
   * @param {NodeListOf<HTMLAnch