I’m sure I must be missing something really, really simple, but what is the tab bar for? I can show it, or hide it, but as I can’t find any way to create additional tabs I’m not sure what purpose it serves. As I said, I must be missing something, but I can’t for the life of me work out what.
I assume you are on macOS. The view menu is part of macOS and the tab bar was introduced for all apps at 1 or 2 macOS annual releases ago. Not all apps take advantage of it. Roon doesn’t. So just ignore it.