Add System Language Changer

[Malsasa]

How if language changer feature added in Ubuntu Tweak? I feel it is easy to edit:

sudo gedit /etc/default/locale
sudo gedit ~/.pam_environment

but it is absolutely easier if anyone can do it in GUI-way via Ubuntu Tweak. Because many times default Ubuntu Language Changer doesn't work well, even I have installer language packs needed. But if I edit manually those 2 files, done. So, it is great if Ubuntu Tweak has this feature.