Better than Tree Style tab but...how to hide horizontal tabs?

I love it

no search bar，my bookmark folder has more than 2000 items，it's very hard for me to find the item I wanted without searching.

ok

Best add on ever for Firefox

If the autohide/autoexpand functionality worked while the sidebar is hidden this would have the exact functionality I want. It wouldn't hurt to have an easier way to theme the appearance, either.