How did the devs implement the tiling windows

I am building an electronjs app as well and I love the tiling window feature of obsidian, the only other app which has this is vscode as far as I know. But because the obsidian community is way more active I would like to ask it here:
How did you implement the tiling window functionality, is it done with a 3rd party framework or is everything done in reactjs (I suppose that uses react).
Some information about this would be huge, I am very new to electron & react etc. so would be nice if you could explain it a bit :).

There is no framework used in Obsidian,
Obsidian does not use React.
We don’t know how this works.