Not displayed debug output in "Application Output" tab on ArchLinux

#include <QApplication>
#include <QLabel>
#include <QDebug>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QLabel l(QLabel::tr("Hello World"));
    l.show();
    qDebug() << "DHello";
    qWarning() << "WHello";
    qCritical() << "CHello";
    return a.exec();
}