I am enjoying this on OSX. I tried Tree Style Tabs in the past, but was not a fan of how it looked. This looks much better and is working nicely so far. In the future it would be nice to see collapse-able tab groups.
Pinned tabs should have a visual distinction, rather than only being pinned to the top. An icon, badge, or subtle change in background shade would work.
One idea I'd just thought of adding might be to use the empty space below the tabs with a top-list of frequently used URLs, excluding those already open. And maybe the most recently closed tabs. Also when mentioning productivity, I immediately thought of putting check boxes or labels on the tabs. Or swipe actions.
Pinned tabs should have a visual distinction, rather than only being pinned to the top. An icon, badge, or subtle change in background shade would work.
Looking good!