Rated 5 out of 5 stars
UPDATE: It now works again with the newest version 0.14.2013082301! Thanks for the fix! Now 5 stars.
This addons is the only reason I still use Firefox, even though Chromium is quicker and more responsive. Chromium lacks vertical tabs.
Last update broke the addon on both Win7 (32 Bit) and Arch Linux (64 Bit).The old one from here works:https://addons.mozilla.org/firefox/downloads/file/210628/tree_style_tab-0.14.2013052901-fx.xpi?src=version-history Thanks to Hiroth for providing the link.