Just getting started with Allegro 5.2.3, and I'm following the tutorial for creating a window. All I've changed is adding the flag for making the window fullscreen. When running on OS X (10.13.2) via Xcode, I get an error reported in the console saying that I'm invoking the UI from the wrong thread. I've done a bit of Googling on this, but haven't found a definitive fix. Has anyone else seen this issue/know a fix?

Relevant code snippet:

int main(int argc, char **argv){
    
    ALLEGRO_DISPLAY *display = NULL;
    
    if(!al_init()) {
        cerr << "failed to initialize allegro!" << endl;;
        return -1;
    }
    
    al_set_new_display_flags(ALLEGRO_FULLSCREEN_WINDOW);
    
    display = al_create_display(800, 600);  // <<--- ERROR OCCURS HERE
    
    //...

    return 0;
}

And the error reported in the console is:

=================================================================
Main Thread Checker: UI API called on a background thread: -[NSOpenGLView initWithFrame:]
PID: 24293, TID: 8372435, Thread name: (none), Queue name: com.apple.root.default-qos.overcommit, QoS: 21
Backtrace:
4   liballegro.5.2.dylib                0x000000010036671d create_display_win + 168
5   liballegro.5.2.dylib                0x0000000100329670 al_create_display + 40
6   MyApp                               0x0000000100001d07 _al_mangled_main + 423
7   liballegro.5.2.dylib                0x0000000100368f99 +[AllegroAppDelegate app_main:] + 23
8   Foundation                          0x00007fff2e013e48 _NSThread__start_ + 1197
9   libsystem_pthread.dylib             0x00000001004576b9 _pthread_body + 340
10  libsystem_pthread.dylib             0x0000000100457565 _pthread_body + 0
11  libsystem_pthread.dylib             0x0000000100456c55 thread_start + 13
2018-01-07 08:23:26.166147-0800 MyApp[24293:8372435] [reports] Main Thread Checker: UI API called on a background thread: -[NSOpenGLView initWithFrame:]
PID: 24293, TID: 8372435, Thread name: (none), Queue name: com.apple.root.default-qos.overcommit, QoS: 21
Backtrace:
4   liballegro.5.2.dylib                0x000000010036671d create_display_win + 168
5   liballegro.5.2.dylib                0x0000000100329670 al_create_display + 40
6   MyApp                               0x0000000100001d07 _al_mangled_main + 423
7   liballegro.5.2.dylib                0x0000000100368f99 +[AllegroAppDelegate app_main:] + 23
8   Foundation                          0x00007fff2e013e48 _NSThread__start_ + 1197
9   libsystem_pthread.dylib             0x00000001004576b9 _pthread_body + 340
10  libsystem_pthread.dylib             0x0000000100457565 _pthread_body + 0
11  libsystem_pthread.dylib             0x0000000100456c55 thread_start + 13
Program ended with exit code: 0

Note: the "error" is not a complier/debugger error, but simply output to the console.

I've heard HORRIBLE things about High Sierra OS X.

[edit]

Hmm this reports:

https://community.esri.com/thread/201929-ios-11-threading-issue

So its not an error, but a warning...

Apologies for letting this go stale without a response.

Thanks for the perspective on this. Currently my (skeleton) program functions fine, just with the noted output in the console. From Apple's documentation, it looks as though this won't happen when compiled with a Release profile, so this is no more than a development nuisance. I assume there's no workaround other than re-writing and recompiling the library with the test fullscreen function on the correct thread?

Regardless, this is my first introduction to the Allegro community, and it's gratifying to get a substantive response so quickly. I'm excited to see what's possible with this library

I was thinking of looking at this at some point (I do have a Mac), but it's not urgent as it doesn't appear to break anything. Filed an issue for this so it's not forgotten: https://github.com/liballeg/allegro5/issues/876