For reference:
https://github.com/mozilla/pdf.js/issues/15571#issuecomment-1278141781
const id = event.dataTransfer.getData("text/plain");
    const editor = this.#uiManager.getEditor(id);
    if (!editor) {
      return;
    }
    event.preventDefault();
    event.dataTransfer.dropEffect = "move";
    this.#changeParent(editor);
    const rect = this.div.getBoundingClientRect();
    const endX = event.clientX - rect.x;
    const endY = event.clientY - rect.y;
    editor.translate(endX - editor.startX, endY - editor.startY);
    this.moveEditorInDOM(editor);
    editor.div.focus();
  }
  /**
   * Dragover callback.
   * @param {DragEvent} event
   */
  dragover(event) {
    event.preventDefault();
  }
  /**
   * Destroy the main editor.
   */
  destroy() {