#include <QApplication>
#include <QPushButton>
#include <QDialog>

int main(int argc, char *argv[]) {
    QApplication a(argc, argv);
    QPushButton w("Click Me...", 0);
    QObject::connect(&w, &QPushButton::pressed, [&]() { QDialog d(0); d.exec(); });
    w.show();
    return a.exec();
}