Exporting to HTML does not save widgets

[LucVV]

Describe the issue

First of all, thank you for the library! I'm running into an issue with exporting my notebooks from Jupyter Lab. I work with 3D figures and want to export the entire notebook as HTML with images in the current state. I was able to do so in Jupyter Notebook with the %matplotlib notebook command. However, when using the export function in Jupyter Lab after calling %matplotlib widget, the output becomes something like:

I'm aware of issue #16, but unsure if it is the same issue? Is there a way around this export problem, or another type of export that can be configured to work?

Versions

python 3.7.9 (default, Aug 31 2020, 17:10:11) [MSC v.1916 64 bit (AMD64)]
ipympl version: 0.6.3
jupyter core     : 4.7.1
jupyter-notebook : 6.2.0
qtconsole        : not installed
ipython          : 7.21.0
ipykernel        : 5.5.0
jupyter client   : 6.1.12
jupyter lab      : 3.0.11
nbconvert        : 6.0.7
ipywidgets       : 7.6.3
nbformat         : 5.1.2
traitlets        : 5.0.5
Known nbextensions:
  config dir: ~\AppData\Local\Continuum\anaconda3\envs\test\etc\jupyter\nbconfig
    notebook section
      jupyter-matplotlib/extension enabled
      - Validating: ok
      jupyter-js-widgets/extension enabled
      - Validating: ok
JupyterLab v3.0.11
~\AppData\Local\Continuum\anaconda3\envs\test\share\jupyter\labextensions
        jupyter-matplotlib v0.8.3 enabled ok
        @jupyter-widgets/jupyterlab-manager v3.0.0 enabled ok (python, jupyterlab_widgets)

Other labextensions (built into JupyterLab)
   app dir: ~\AppData\Local\Continuum\anaconda3\envs\Test\share\jupyter\lab

[martinRenou]

This should be fixed with ipympl>=0.8.0 and next nbconvert release, when this gets released jupyter/nbconvert#1643