SDL_WINDOWPOS_UNDEFINED_DISPLAY3
Used to indicate that you don't care what the window position is.
Usage
#include "SDL3/SDL.h"
#define SDL_WINDOWPOS_UNDEFINED_DISPLAY(X) (SDL_WINDOWPOS_UNDEFINED_MASK|(X))
Header file
Defined in SDL3/SDL_video.h
Overview
If you _really_ don't care,
SDL_WINDOWPOS_UNDEFINED
is the same, but always uses the primary display instead of specifying one.