More hacking to make macOS happy...

Allow ALT+Arrow to resize from maximized by calling
SDL_RestoreWindow() first.  This should allow macOS users to escape
the weird window size mess it can start in.  Still no idea what is
actually happening there, but this should at least provide an "out"
now. :(

src/conio/sdl_con.c

@@ -63,7 +63,7 @@ int sdl_ufunc_retval;
 sem_t sdl_flush_sem;
 int pending_updates=0;
 
-int fullscreen=0;
+int fullscreen = 0;
 
 int	sdl_init_good=0;
 pthread_mutex_t sdl_keylock;
@@ -395,7 +395,7 @@ int sdl_init(int mode)
 	bitmap_drv_init(sdl_drawrect, sdl_flush);
 
 	if(mode==CIOLIB_MODE_SDL_FULLSCREEN)
-		fullscreen=1;
+		fullscreen = 1;
 	// Needs to be *after* bitmap_drv_init()
 #if defined(__DARWIN__)
 	sem_post(&startsdl_sem);
@@ -924,24 +924,23 @@ void sdl_video_event_thread(void *data)
 					if ((ev.key.keysym.mod & KMOD_ALT) &&
 					    (ev.key.keysym.sym == SDLK_LEFT ||
 					     ev.key.keysym.sym == SDLK_RIGHT)) {
-						// Don't allow ALT-DIR to change size when maximized...
-						if ((sdl.GetWindowFlags(win) & SDL_WINDOW_MAXIMIZED) == 0) {
-							int w, h;
-							SDL_Rect r;
-							if (sdl.GetDisplayUsableBounds(0, &r) == 0) {
-								w = r.w;
-								h = r.h;
-							}
-							else {
-								w = 0;
-								h = 0;
-							}
-							pthread_mutex_lock(&vstatlock);
-							bitmap_snap(ev.key.keysym.sym == SDLK_RIGHT, w, h);
-							pthread_mutex_unlock(&vstatlock);
-							update_cvstat(&cvstat);
-							setup_surfaces(&cvstat);
+						if (sdl.GetWindowFlags(win) & SDL_WINDOW_MAXIMIZED)
+							sdl.RestoreWindow(win);
+						int w, h;
+						SDL_Rect r;
+						if (sdl.GetDisplayUsableBounds(0, &r) == 0) {
+							w = r.w;
+							h = r.h;
+						}
+						else {
+							w = 0;
+							h = 0;
 						}
+						pthread_mutex_lock(&vstatlock);
+						bitmap_snap(ev.key.keysym.sym == SDLK_RIGHT, w, h);
+						pthread_mutex_unlock(&vstatlock);
+						update_cvstat(&cvstat);
+						setup_surfaces(&cvstat);
 						break;
 					}
 				}
@@ -1051,10 +1050,9 @@ void sdl_video_event_thread(void *data)
 						// Fall-through
 					case SDL_WINDOWEVENT_SIZE_CHANGED:
 						// SDL2: User resized window
-					case SDL_WINDOWEVENT_RESIZED: {
-						int flags = sdl.GetWindowFlags(win);
-						fullscreen = (flags & (SDL_WINDOW_FULLSCREEN | SDL_WINDOW_FULLSCREEN_DESKTOP)) != 0;
-						sdl.SetWindowResizable(win, (flags & (SDL_WINDOW_FULLSCREEN | SDL_WINDOW_FULLSCREEN_DESKTOP)) ? SDL_FALSE : SDL_TRUE);
+					case SDL_WINDOWEVENT_RESIZED:
+						fullscreen = !!(sdl.GetWindowFlags(win) & (SDL_WINDOW_FULLSCREEN | SDL_WINDOW_FULLSCREEN_DESKTOP));
+						sdl.SetWindowResizable(win, fullscreen ? SDL_FALSE : SDL_TRUE);
 						cio_api.mode=fullscreen?CIOLIB_MODE_SDL_FULLSCREEN:CIOLIB_MODE_SDL;
 						pthread_mutex_lock(&sdl_mode_mutex);
 						if (sdl_mode) {
@@ -1064,7 +1062,6 @@ void sdl_video_event_thread(void *data)
 						pthread_mutex_unlock(&sdl_mode_mutex);
 						internal_setwinsize(&cvstat, false);
 						break;
-					}
 					case SDL_WINDOWEVENT_EXPOSED:
 						bitmap_drv_request_pixels();
 						break;

src/conio/sdlfuncs.c

@@ -214,6 +214,10 @@ int load_sdl_funcs(struct sdlfuncs *sdlf)
 		xp_dlclose(sdl_dll);
 		return(-1);
 	}
+	if((sdlf->RestoreWindow=xp_dlsym(sdl_dll, SDL_RestoreWindow))==NULL) {
+		xp_dlclose(sdl_dll);
+		return(-1);
+	}
 #ifndef STATIC_SDL
 	{
 		int (HACK_HACK_HACK *ra)(char *name, Uint32 style, void *hInst);

src/conio/sdlfuncs.h

@@ -59,6 +59,7 @@ struct sdlfuncs {
 	void(HACK_HACK_HACK *free)	(void *);
 	Uint32(HACK_HACK_HACK *GetWindowFlags)	(SDL_Window * window);
 	int (HACK_HACK_HACK *GetDisplayUsableBounds) (int, SDL_Rect *);
+	void (HACK_HACK_HACK *RestoreWindow) (SDL_Window *);
 	int	gotfuncs;
 };