So here's a short version of my post:
It enables you to stretch windows over multiple screens but unfortunately the result is very annoying to work with and only slightly usable if both screens have the same resolution. Even then you have a giant window stretching over multiple displays leading to enormous annoyances (like having to do minutes of undocking and reordering everything every time you start the app).
I see. That seems very annoying. Maybe this is just a Mac limitation, hopefully this feature will be available in upcoming chrome versions or something, I can't really find any better solution so far. I'll update the thread here in case I find any proper solution to that.