#include <QAction>
#include <QApplication>
#include <QDebug>
#include <QWidget>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QWidget w;
    auto action = new QAction(&w);
#ifdef Q_OS_MAC
    action->setShortcut(QString::fromLatin1("Alt+Tab"));
#else
    action->setShortcut(QString::fromLatin1("Ctrl+Tab"));
#endif
    QObject::connect(action, &QAction::triggered, &w, []() { qDebug() << QApplication::keyboardModifiers(); });
    w.addAction(action);

    w.show();

    return a.exec();
}