Fullscreen and coordonates questions in GL context

Hello, i m discovering with great pleasure OpenFrameworks.

actually i m making some tests on a Surface Pro w10 wich is 2736x1824

compiling with VS 2015 Studio v 098, in fullscreen mode, no problem.

the app appears in FScreen and coordonates x and y are ok.

But if i set my screen in another resolution the fullscreen disappears, and the window is truncanated and not at all FScreened.

here is a snapshot in resolution 1920x1080 and below the code used to intitalize the window

is there anything i m missing ? thxs

void ofApp::setup(){

	ofSetWindowTitle("...");
	ofSetWindowShape(1920, 1080);

}

int main( ){
	ofSetupOpenGL(1920,1080,OF_FULLSCREEN);			// <-------- setup the GL context

	// this kicks off the running of my app
	// can be OF_WINDOW or OF_FULLSCREEN
	// pass in width and height too:
	ofRunApp(new ofApp());

}