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

@@ -924,8 +924,8 @@ 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) {
+						if (sdl.GetWindowFlags(win) & SDL_WINDOW_MAXIMIZED)
+							sdl.RestoreWindow(win);
 						int w, h;
 						SDL_Rect r;
 						if (sdl.GetDisplayUsableBounds(0, &r) == 0) {
@@ -941,7 +941,6 @@ void sdl_video_event_thread(void *data)
 						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;
 };