Comment 3 for bug 700213

On the other hand, this works:

LANGUAGE=de gedit

And it launches gedit in German as expected.

Some more tests:

My installed languages are:
ls /usr/share/locale-langpack/
ar ca@valencia en en@boldquot en_GB en@quot en_US es
ca de en_AU en_CA en_NZ en@shaw en_US@piglatin zh_CN

$ LANGUAGE=ca gettext -d evince "All Files"
Tots els fitxers
=> Works as expected

$ LANGUAGE=es gettext -d evince "All Files"
Todos los archivos
=> Works as expected

$ LANGUAGE=de gettext -d evince "All Files"
Alle Dateien
=> Works as expected