Backspace-is-back is not related to Ubuntu extension, see e.g. http://ubuntu.wordpress.com/2006/12/21/fix-firefox-backspace-to-take-you-to-the-previous-page/
Backspace-is-back is not related to Ubuntu extension, see e.g. http:// ubuntu. wordpress. com/2006/ 12/21/fix- firefox- backspace- to-take- you-to- the-previous- page/