So my demo program runs fine when I run it from the terminal. It creates a SDL Window and blits lots of numbers, but if I try to start it in the debugger, it gets to this function and fails in the SDL_CreateWindowAndRenderer.

void InitSetup() {
	srand((int)time(NULL));
	SDL_Init(SDL_INIT_EVERYTHING);
	SDL_CreateWindowAndRenderer(WIDTH, HEIGHT, SDL_WINDOW_SHOWN, &screen, &renderer);
	if (!screen) {
		LogError("InitSetup failed to create window");
	}
	SetCaption("Example Two");
	LoadTextures();
}

And in the Debug Console I can see two of these:

@”error: XDG_RUNTIME_DIR not set in the environment.\r\n”

followed by my error message InitSetup failed to create window.

I’ve looked online and there’s one or two mentions. Now possibly it might be because I’m running Ubuntu 18.04 LTS under Hyper-V Manager.  I’ll try this on a laptop where I’ve installed the same version of Ubuntu on and see if the same thing happens.