Single Sign-On with OAuth 2 - [DEPRECATED]

Gotta say that without the brand new X-Cart OAuth v.2 Add-on module for my shopping cart at http://www.relativitycalculator.com/X-Cart/, it would still not be possible to configure this function as previously I had earlier tried using some of Google's so-called "instructions" but to absolutely no success. However with the brand new X-Cart OAuth v.2 Add-on module, my shopping cart has been considerably enhanced. Therefore I must give the recent authors of OAuth v.2 Add-on module an excellent rating of 5 stars out of 5 as do I overall give for X-Cart shopping cart and their outstanding software engineers and support!