You might need to enable data access permission for it to work.

Go to about:addons, select the addon and go to permission tab and enable permission for the google translate site. For me it is "Access your data *.//translate.google.com" which should be enabled.

Does not work anymore

It is a very good extension. It improve the productivity a lot!

doesnt work anymore

Thanks for this extension. It has improved my productivity a lot!

Shortcuts have stopped working on Nov. 4.
(I believe the cause are changes in Google Translator itself.)

Some keyboard layouts use the AltGr key to input diacritics. This extension interferes with that - would you consider differentiating Alt and AltGr in your code?