SDL - fix re-entrancy into SDL_UpdateFullscreenMode under OSX. During HideWindow we get a RESTORED event which then turns fullscreen back on causing a hang in Cocoa_SetWindowFullscreenSpace waiting for the fullscreen transition to finish.

src/video/SDL_sysvideo.h

@@ -93,6 +93,7 @@ struct SDL_Window
     SDL_Surface *surface;
     SDL_bool surface_valid;
 
+    SDL_bool is_hiding;
     SDL_bool is_destroying;
 
     SDL_WindowShaper *shaper;

src/video/SDL_video.c

@@ -1105,6 +1105,10 @@ SDL_UpdateFullscreenMode(SDL_Window * window, SDL_bool fullscreen)
 
     CHECK_WINDOW_MAGIC(window,);
 
+    /* if we are in the process of hiding don't go back to fullscreen */
+    if ( window->is_hiding && fullscreen )
+        return;
+    
 #ifdef __MACOSX__
     if (Cocoa_SetWindowFullscreenSpace(window, fullscreen)) {
         window->last_fullscreen_flags = window->flags;
@@ -1833,11 +1837,13 @@ SDL_HideWindow(SDL_Window * window)
         return;
     }
 
+	window->is_hiding = SDL_TRUE;
     SDL_UpdateFullscreenMode(window, SDL_FALSE);
 
     if (_this->HideWindow) {
         _this->HideWindow(_this, window);
     }
+	window->is_hiding = SDL_FALSE;
     SDL_SendWindowEvent(window, SDL_WINDOWEVENT_HIDDEN, 0, 0);
 }