Gets a reference to the default user handle for GDK.
Defined in <SDL3/SDL_system.h>
outUserHandle | a pointer to be filled in with the default user handle. |
Returns 0 if success, -1 if any error occurs.
This is effectively a synchronous version of XUserAddAsync, which always prefers the default user and allows a sign-in UI.
This function is available since SDL 3.0.0.