Output not rendered in the right place

[DonJayamanne]

• Run the sample here https://github.com/microsoft/scenepic/blob/main/python_examples/tutorial.ipynb
• Either in Jupter Lab or Jupyter Notebook
• Save the notebook, close Jupyter
• Restart Jupyter lab or notebook
• Re-open the notebook
• You'll see that the outputs are not in the right place,
  The postions of the outputs are pretty random, sometimes all of the outpts appear under a single cell, some times we have two outputs under a single cell and rest under another.

I can repro this same problem in Jupyter Lab, Notebook (& VS Code with a few fixes, not yet released).