Is your feature request related to a problem? Please describe.
Hello 👋
I'm working on a project that changes the layout using dockviewApi.fromJSON to load different layouts but from a fixed list of panels. So, in one layout I could have only one panel visible and in another, I have 2 columns of 3 and 2 panels side by side.
These panels show iframes which is important to be kept alive on changing the layout.
The current state of DockView to my understanding is that using fromJSON will cause removing all the extra panels. Is there any way around it?

Describe the solution you'd like
I'm not sure what's the best solution here. I saw #397 but it seems it's not available anymore.

Describe alternatives you've considered
I'm trying to see if using portals and mirroring (somehow) could work here. Or maybe move the extra ones to a floating group and hide that.