On Apple platforms, the main thread is the thread that runs your program's
main() entry point. On other platforms, the main thread is the one that
calls SDL_Init(SDL_INIT_VIDEO), which should usually be the one that runs
your program's main() entry point. If you are using the main callbacks,
SDL_AppInit(), SDL_AppIterate(), and SDL_AppQuit() are all called on the
main thread.
Return whether this is the main thread.
On Apple platforms, the main thread is the thread that runs your program's main() entry point. On other platforms, the main thread is the one that calls SDL_Init(SDL_INIT_VIDEO), which should usually be the one that runs your program's main() entry point. If you are using the main callbacks, SDL_AppInit(), SDL_AppIterate(), and SDL_AppQuit() are all called on the main thread.