type, which is currently "jpeg",
"png", "ico" or "bmp".  If error is set, FALSE will be returned. See
gdkPixbufSaveToCallback for more details.gdkPixbufSaveToCallbackv(object, save.func, user.data, type, option.keys, option.values, .errwarn = TRUE)save.funcGdkPixbufSaveFunc]  a function that is called to save each block of data that
  the save routine generates.user.datatypeoption.keysNULL-terminatedoption.valueserrorGError]  return location for error, or NULL