This extension open a bubble that can you click on when you select a text on the page and show a iframe of the google translate in your browser page. It is similar to the google translate extension.
First you should change the default language settings by accessing to about:addons > Translate Extension option page.
You can test the extension in Firefox with web-ext. web-ext can be installed with the Node Package Manager.
sudo npm install --global web-ext
Download the code from Github
git clone https://github.com/fuatkarakus/translate-extension.git
cd translate-extension
make prepare
Run in the root folder extension the command
web-ext run