Be careful with old versions!
These versions are displayed for reference and testing purposes. You should always use the latest version of an add-on.
Because of some new preferences that I found (such as the controls for the tab previews), as well as the other changes made in this release, the locale strings have changed considerably - many of them are still the same, but there are new ones that will need to be localized.
The internal layout of the XUL overlay used to expose the preferences also has some minor changes, mainly to assist theme developers.