Vertical tabs feedback

I've been trying out vertical tabs for a few days now and I'm getting used to them.

It's true that it gives you more space to navigate!

I do have a few criticisms, though: for videos (like YouTube), the "mute" button takes up too much space and is often missclicked, also I'd prefer a play/pause button instead.

Customization of vertical tabs is too weak, and should be made possible by customizing the existing toolbar.

Unrelated to vertical tabs, but still in the same topic : following on from the "space savings", I'd really appreciate a new display option for the personal bar and toolbar that would display them when the mouse is over it (at the top for me), like the Windows taskbar.