[wintermutestwin]

You are right - but I don't count their implementation because it is incredibly lacking in basic functionality. Notice how the vertical "tabs" don't have a close X and the annoying padding that cuts off the tab name to replace it with "... "

Also, every time I open Safari, I have to manually click the ... and "Show tabs on sidebar" - for each tab group!

This is a total half assed implementation - I seriously doubt there are many who will use it in its current form.