When using the vertical layout, there is a lot of space wasted when using the expanded view on a single screen.
I often switch between my media pool and my effects library, which in previous versions I could have all listed in one place to the left of the screen, making everything I need accessible at the same time. However the new vertical mode prevents you from extending the left menu and you are limited to one tab and maybe I'm just being resistant to change, but I hate how I now have to constantly switch between my media pool and effects library.
My suggestion would be to allow for two tabs to open in the upper left corner of the ui, as shown in the images below.

- Red box indicates the section referred to in the post
- UI1.jpg (675.64 KiB) Viewed 165 times