If an error occurs during execution of a program, the error message received
from glibc is sent directly to pango, without converting it from locale to
utf-8.

Try:
LANG=hu_HU.UTF-8 xfrun4
type an invalid executable name and press Enter. A nice error message box
appears and everything is perfect.

Now try:
LANG=hu_HU xfrun4
type an invalid executable name and press Enter. The error box only contains
"Nem l" and this is printed on stderr:
** (xfrun4:12345): WARNING **: Invalid UTF8 string passed to 
pango_layout_set_text()