#include <QApplication>
#include <QPushButton>
int main(int argc, char **argv)
{
    QApplication app (argc, argv);
    QPushButton button ("Hello world !");
    button.show();
    return app.exec();
}

HEADERS += Qt/mainwindow.h
    Qt/MPrintableWidget.h
    Qt/MPrintableWidgetGroup.h    # Oooops forgot the  here
    Qt/MFixedSizeDialog.h
    Qt/MScreenPage.h

g++ -fPIC -I /usr/include/qt5/QtWidgets -I /usr/include/qt5 qttest.cpp -o qttest -lQt5Core -lQt5Widgets