If a long option in the main group has this name, it is not treated as a
regular option. Instead it collects all non-option arguments which would
otherwise be left in argv. The option must be of type
G_OPTION_ARG_CALLBACK, G_OPTION_ARG_STRING_ARRAY
or G_OPTION_ARG_FILENAME_ARRAY.
Using G_OPTION_REMAINING instead of simply scanning argv
for leftover arguments has the advantage that GOption takes care of
necessary encoding conversions for strings or filenames.
If a long option in the main group has this name, it is not treated as a regular option. Instead it collects all non-option arguments which would otherwise be left in argv. The option must be of type G_OPTION_ARG_CALLBACK, G_OPTION_ARG_STRING_ARRAY or G_OPTION_ARG_FILENAME_ARRAY.