title: What exactly is the purpose of the JupyterLab extension of ipywidgets?
body: <p>According to this: <a href="https://ipywidgets.readthedocs.io/en/stable/user_install.html" rel="nofollow noreferrer">https://ipywidgets.readthedocs.io/en/stable/user_install.html</a> , in order to use ipywidgets on a legacy Jupyter Notebook, one has to install the appropriate Jupyter Notebook extension like this:</p>
  
  <pre><code>pip install ipywidgets
  jupyter nbextension enable --py widgetsnbextension
  </code></pre>
  
  <p>Moreover, in order to use ipywidgets from a Notebook that runs through JupyterLab, one was to install the JupyterLab extension of ipywidgets using:</p>
  
  <pre><code>jupyter labextension install @jupyter-widgets/jupyterlab-manager
  </code></pre>
  
  <p>Why is that the case? I was under the impression that the Notebook of JupyterLab is just a legacy Jupyter Notebook that is packed as an extension of JupyterLab. I tried to read through the code of the ipywidgets JupyterLab extension but I am not sure what is going on.</p>
  
  <p>I would appreciate if someone could list the most important reasons as to why installing just the Jupyter Notebook extension of ipywidgets is not enough when running Notebooks through JupyterLab.</p>
  
  <p>Thanks in advance.</p>