Provided by: libsdl3-doc_3.2.20+ds-2_all 

NAME
SDL_WINDOWPOS_ISUNDEFINED - A macro to test if the window position is marked as "undefined."
SYNOPSIS
#include <SDL3/SDL_video.h>
#define SDL_WINDOWPOS_ISUNDEFINED(X) (((X)&0xFFFF0000) == SDL_WINDOWPOS_UNDEFINED_MASK)
MACRO PARAMETERS
X the window position value.
AVAILABILITY
This macro is available since SDL 3.2.0.
Simple Directmedia Layer SDL 3.2.20 SDL_WINDOWPOS_ISUNDEFINED(3)