In this version, you may choose to link the button to either LivingSocial or any of Groupon international sites, in addition, youcan now choose to open link in new or current tab.  All of these features are available by right clicking on the button, and choose from popup menu, while it remains unchanged that left clicking on the button leads you to the Groupon (or LivingSocial) site conveniently.

Download Groupon Button from Firefox official addon site.  Check out the full manual of this addon.

Screenshots