Gtk-WARNING **:

[Moltke]

It's not an "issue" per se, at least not one you should worry about. If you try running all of the software you've installed right from the terminal you'd probably  find that many of them would trigger this gtk warning, the reason is that when you launch a GUI app from whisker menu it gets a completely different set of environment variables than programs run from the terminal. In general, neither LANG nor any of the LC_* variables will be set for a GUI app. If you run

Code:

locale

from the terminal you'll see something similar to this

Code:

LANG=es_VE.utf8
LANGUAGE=
LC_CTYPE="es_VE.utf8"
LC_NUMERIC="es_VE.utf8"
LC_TIME="es_VE.utf8"
LC_COLLATE="es_VE.utf8"
LC_MONETARY="es_VE.utf8"
LC_MESSAGES="es_VE.utf8"
LC_PAPER="es_VE.utf8"
LC_NAME="es_VE.utf8"
LC_ADDRESS="es_VE.utf8"
LC_TELEPHONE="es_VE.utf8"
LC_MEASUREMENT="es_VE.utf8"
LC_IDENTIFICATION="es_VE.utf8"
LC_ALL=

As you can see "Language" and "lc_all" are empty and as far as I know that how's supposed to be since different programs will use different set of settings, in conclusion, the gtk warning is the program saying "hey, is this a shell?" and nothing more, like I  said nothing to be worried about really.

Hope this helps!