png_simple_warning_callback(png_structp png_save_ptr,
                            png_const_charp warning_msg)
{
        /* Don't print anything; we should not be dumping junk to
         * stderr, since that may be bad for some apps. If it's
         * important enough to display, we need to add a GError
         * **warning return location wherever we have an error return
         * location.
         */
}
png_simple_warning_callback(png_structp png_save_ptr,
                            png_const_charp warning_msg)
{
         
}