Wrong mouse click behavior for QWidget

#include <QtWidgets/QtWidgets>

class Button:public QPushButton
{
public:
    explicit Button():QPushButton("Press Me!"){}

protected:
    void mousePressEvent(QMouseEvent *e)
    {
        qDebug("press");
        QPushButton::mousePressEvent(e);
    }
    void mouseReleaseEvent(QMouseEvent *e)
    {
        qDebug("release");
        QPushButton::mouseReleaseEvent(e);
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Button btn;
    btn.show();
    return a.exec();
}

press
release
press
press
release
press
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