If you start getting many nested items, the navigator panel has a left/right scroll. Could the panel itself be resizable? Like any browser, web developer tools when you have the panels on the side.
I actually built it off one of Alex's demo projects. I have a couple nested collections in there as well so I can handle arrays. I don't think I have many elements that aren't needed.
@szilardm8, I was the original request of this and have completely forgotten about it. Someone recommended that I simply press shift when I scroll and I can horizontaly scroll. It's become second nature and is fast. Maybe this will work for you as well?
It might be? Personally I see them developing other features/requests and those are often greater benefits to me than this request. Maybe in time, they will add this too?