I do like the new piece selector better than the old one, but I also think it could use a scroll bar.
Yeah, it's a lot of clicking otherwise, I've noticed that as well
. Besides, the old editor tileset selection has a scrollbar, too. And the last thing the new formats editor needs is further downgrades from version 10.13
!
With the scrollbar however, the new editor would allow to create levels much more quickly than the old one, because the selection is always right there, without having to right-click all the time, and could still be navigated just as quickly via scrolling. That would be something it would have going for it, then!