During the POC, we found some issues on VSCode core:

Some of them are already tracked:
https://github.com/Microsoft/vscode/issues/5604
https://github.com/Microsoft/vscode/issues/12176

And other ones aren't, i.e.:

The first viewport open doesn't follow the VSCode lifecycle.

We should talk with VSCode Team, in order to see if those issues can be fixed and also if we can submit PR's to their codebase.