Unhelpful error message

["Ronald F. Guilmette" <rfg tristatelogic com>]

I get the following message often, usually (apparently) as a by-product
of running some browser (e.g. Firefox) or another (e.g. Opera):

    (process:22681): Gtk-WARNING **: Locale not supported by C library.
            Using the fallback 'C' locale.

I googled it and quite obviously I am far from alone in being frequently
annoyed by this message.

Would the authors/maintainers of GTK mind very much improving the message,
you know, so that it would at least give the user the *name* of the specific
offending locale that GTK is actually complaining about?  I mean is that
too much to ask?

I do believe that that one key piece of missing information would be
rather helpful to those thousands of people, including me, who are
trying to understand the genesis of this error and also how to suppress
it.