I tried it out and it seems clear that vertical tabs without titles create too much friction for daily driving a browser where you have many tabs open, hover thumbnails or not.

For a few years I have thought that Firefox could gain market share by doing more with the browser UI, steal a few ideas from Arc Browser for instance. There's a lot of value to be added in the UI for sure.

Asking users what they want and then building it ends up with solutions like these. I really hope this gets a lot more iteration before landing in stable.

I currently use SlidePad on Mac which allows touching the left side of the screen to pop out a vertically tabbed browser, for IMs and most used AI chat but would rather keep everything in Firefox with some kind of panel system. I think most of us have pinned tabs for communication channels, email, socials, etc.

Vertical tabs on left with titles works if you can also configure a useful slide out panel on right, mixing the two feels odd to me.

But really good to see something happening finally, so good news overall.