Very good with one small danger on the Mac using the contextual menu Rated 4 out of 5 stars
I love it - basically. Could not live without it anymore. I found that the best setting is to have it at the tab position at the "Rightside" and choose the skin "Mixed".
I found some glitches in version 0.14.2012050301
1. When on the right side "Auto hide tab bar" does not really work.
2. But here's the most dangerous problem - if you're a Mac user. You know on the Mac, when you right click (Control-click) -- the contextual menu window stays open and you can let go of the mouse. Then you normally can take your time and safely select what you want to do and click the selection. However here with this Firefox add on the menu MAY not stay open and it will immediately select AND EXECUTE the menu item where you have been hovering over at the moment when you let go of the click. The only situation where it behaves like on a Mac is when you happened to be with your cursor OUTSIDE of the menu when clicking. Unfortunately - often - the cursor is INSIDE the menu already with all the immediate and potentially nasty consequences...
I have compared the behavior of the contextual menu here with the contextual menu in Finder on the Mac. The Mac always creates the contextual menu AWAY from the cursor. That would be the solution here too. I sure hope this gets updated soon because currently I sometimes "Close" some tabs by accident :(
For Info: I'm also using the extension "Multiple Tab Handler" - maybe this is related? I'm on Mac OS X 10.7.4 Lion using Firefox 13.0.1.