WebStorm 2020.1 VCS (git) diff preview layout 3 columns

I've just migrated to WebStorm 2020.1 and thought I'd swap to the new git commit layout.
While a little confusing at first there's a separation of concerns, two windows to the the same thing done. I was OK with it until I saw that the Diff Preview has been change to appear under the file list. This is now happening for the git log as well. I changed back to the old Commit Window mode, but the diff preview layout is still the same.

How can I change the layout back to three columns?

This is the new layout in 20201. A lot of wasted space on the right of the file column, with the diff appearing in a short row under.

I want it to appear like this (as it was in 2019.3)