{ "extract-to=FOLDER", 'x', 0, G_OPTION_ARG_FILENAME,
&extract_path, "Extract the archive to the specified folder and
quits.", NULL },
Should be:
{ N_("extract-to"), 'x', 0, G_OPTION_ARG_FILENAME,
&extract_path, N_("Extract the archive to the specified folder and
quits."), N_("FOLDER")},
IIRC...
Nick