The spec for this action:
https://www.adobe.com/content/dam/acom/en/devnet/pdf/pdfs/PDF32000_2008.pdf#G11.2111850
An example of a form using this action:
https://www2.illinois.gov/rev/forms/reg/Documents/reg-1-mr.pdf
if (pin) {
      this.pinned = true;
    }
    if (this.hideElement.hidden) {
      this.hideElement.hidden = false;
      this.container.style.zIndex += 1;
    }
  }
  /**
   * Hide the popup.
   *
   * @private
   * @param {boolean} unpin
   * @memberof PopupElement
   */
  _hide(unpin = true) {
    if (unpin) {
      this.pinned = false;
    }
    if (!this.hideElement.hidden && !this.pinned) {
      this.hideElement.hidden = true;
      this.container.style.zIndex -= 1;
    }
  }
}
class FreeTextAnnotationElement extends AnnotationElement {