Rated 3 out of 5 stars
As an Opera user, this makes Firefox a bit more bearable. I cannot fathom why Firefox and Chromium don't have this built-in.
Seems to work perfectly on Aurora.
Edit: I spoke too soon. Ctrl+Z undoes the last closed tab when you have a text box in another tab selected, meaning it is impossible to undo text without disabling the addon (or resorting to some other weird method that no-one should have to do)
Ctrl+Z should not undo the last closed tab if a text box in your current tab is selected. 5 stars edited down to 3 stars.