Sometime, a ways back, I added a button on the "operations" bar that dropped down into a list of all "Tab Groups". One one of my computers, the upgrade from 12->13 dropped this button, and I can't figure out how to recreate it.
Here's what it looks like
When I select "Customize" on the "Operations" toolbar, and right click the button I get this
When I select "Edit..."
I captured these screenshots from the computer that didn't lose the option. Now if I can just figure out how to recreate it...