Notebook sticky scroll does not show correct element based viewport

[isidorn]

Testing #210961

Open the attached file. Rename to .ipynb
Navigate to the middle of the file (for example where Header 10 is mentioned).
Notice how the sticky scroll outline shows the wrong element. It is not based on keyboard focus, or what is at the screen. It seems like it is a couple of cells off in the computation.

Header 10 is off screen. It is one page above.

test.json

[amunger]

I saw something similar, header 3.1 only shows up just before 3.2

[DonJayamanne]

Yes, I too can replicate this in stable.

Sample ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Header 10\n",
    "\n",
    "## Header 20\n",
    "\n",
    "### header 30\n",
    "\n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   \n",
    "Large contents   "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "metadata": {}
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n"
     ]
    }
   ],
   "source": [
    "print(1)\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Header 1\n",
    "\n",
    "## Header 2\n",
    "\n",
    "### header 3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "metadata": {}
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n"
     ]
    }
   ],
   "source": [
    "print(1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Header 1\n",
    "\n",
    "## Header 2\n",
    "\n",
    "### header 3"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 1234"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Header 1\n",
    "\n",
    "## Header 2\n",
    "\n",
    "### header 3"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": ".venv",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.12.2"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}