Qt::FramelessWindowHint flag does not work

When I run even a simple app the frame and windows title is still there when using uwp. When compiling in win32, everything works fine.

 
attachments are not working so here is the sample

int main(int argc, char *argv[])

{ QApplication a(argc, argv); MainWindow w; w.show(); return a.exec(); }

MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)

{ setWindowFlags(Qt::FramelessWindowHint); ui->setupUi(this); }