#include <QtWidgets>

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    QWidget w;
    w.resize(500, 500);
    w.show();

    auto w2 = new QWidget();
    w2->setWindowModality(Qt::ApplicationModal);
    w2->resize(200, 200);
    w2->show();

    qApp->setOverrideCursor(Qt::SizeAllCursor);

    return app.exec();
}