multiMonitorFullscreen not working on MacOSX


To preface this post by saying that I have some experience with OpenGL and C++ but am very new to openFrameworks. I’m trying to get an app to run fullscreen on multiple monitors.

I’m running two 1920x1080 on a mac mini, both connected with HDMI cables and HDMI-thunderbolt adapters.

Setting up my app as follows:

int main() {
    ofGLFWWindowSettings settings;
    settings.multiMonitorFullScreen = true;// <-----
    ofRunApp(new ofApp());

Any pointers would be appreciated.


Hi @Craigson. Nothing looks wrong to me…what version of OF are you using? I just finished a project on 0.9.3 and multi-screen fullscreen was working for me. I was using a slightly different syntax which may make a difference?

ofGLFWWindowSettings settings;
settings.width = 1920 * 5;
settings.height = 1080;
settings.resizable = false;
settings.decorated = false;
settings.multiMonitorFullScreen = true;

shared_ptr<ofAppBaseWindow> mainWindow = ofCreateWindow(settings);
shared_ptr<ofApp> mainApp(new ofApp);

ofRunApp(mainWindow, mainApp);

Note that I was calling ofSetFullscreen(true) inside ofApp::setup(), but I would think doing either window_sp->setFullscreen(true) like you are or settings.windowMode = OF_FULLSCREEN should work as well.

1 Like

Hey Matt,

Thanks for the response. I’m using the 0.9.3 release. I’ll try moving the setFullScreen() method to setup when im back at my laptop. Anything special i should be doing with the display settings in OSX? Currently set to extended, should they be mirrored?

did you try this


I will try it when i have acceas to the dual monitors on monday and let you know the result, thanks!

Thanks! That solved the problem!