Comment 1 for bug 510023

Hello Loeki,

If you try to set locally the other locale the the default one you will have this exception
When you execute the following command to set locale on your python prompt you will get the original Exception . i.e
locale.setlocale(locale.LC_ALL,'nl_NL')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.6/locale.py", line 513, in setlocale
    return _setlocale(category, locale)
locale.Error: unsupported locale setting

So,
The gtk tries to set your default locale to nl_NL by locale.setlocale() but your machine does not have the entry in its locale file. ie you need to explicitly make an entry of the locale needed by following ways:
1: using the command:
                      sudo locale-gen 'nl_NL.UTF-8'
2: manually edit the file
                      /var/lib/locales/supported.d/local and make the entry of the locale you need.

Then when you restart the gtk . It will easily set the locale.

Thanks,