Disable fullscreen Spaces support (macOS)

* If enabled it causes this annoying system alert sound to be played each time BOINC spawned our app via its screensaver!

src/framework/WindowManager.cpp

@@ -40,6 +40,9 @@ bool WindowManager::initialize(const int width, const int height, const int fram
 	// allow screensaver (or we might block BOINC's own, our parent)
 	SDL_SetHint(SDL_HINT_VIDEO_ALLOW_SCREENSAVER, "1");
 
+	// needed to prevent a system alert sound when launched by BOINC's screensaver on macOS
+	SDL_SetHint(SDL_HINT_VIDEO_MAC_FULLSCREEN_SPACES, "0");
+
 	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) < 0) {
 		cerr << "Window system could not be initalized: " << SDL_GetError() << endl;
 		return false;