On workspace restart: browser tabs don't reopen non-default workspaces

Describe the bug

This is probably between bug report and feature request as I couldn't find documentation for my workflow:
I have a project with one main language (python) and a subproject in a different language (C++). For plugins to work nicely I open the subproject in a separate tab (<default_workspace_url>/mysubfolder). This works nicely.
However, if the gitpod workspace is stopped and restarted, both browser tabs open the root workspace and the state (e.g. open files) of the subproject-workspace is lost. (workspace is used for two different things in gitpod? for the gitpod workspace instance and the theia workspace?)

Steps to reproduce

1. Start a workspace
2. Open a sub-folder of the root workspace in a new browser tab and open some files
3. Stop and restart the gitpod workspace (keeping browser tabs open)
4. Both browser tabs open the root workspace and only the state of the root workspace is persisted

Expected behavior

Instead of 4 above, I would expect that each browser tab re-opens with the correct (sub-)workspace and previous state of each workspace.

Start by reproducing the restart flow: open a root workspace and a sub-folder workspace in separate browser tabs, then stop and restart the workspace. Trace the browser-tab restoration and workspace-state persistence entry points; done means each tab reopens its correct sub-workspace with its previous state.