GSTranslator2 is a second version of simple translator integrated with Gnome Shell. It uses Google Translate technology.
GSTranslator2 consists of service written in Python 2.7, and Gnome Shell Extension.
Please read README file for more info (installation, dependencies, etc.): https://github.com/thof/gstranslator2#readme
You may be interested in the first version of GSTranslator https://github.com/thof/GSTranslator, which actually works fine on Gnome 3.4.1.