Using setFocusProxy can result in multiple buttons having focus

#include <QApplication>
#include <QHBoxLayout>
#include <QLineEdit>
#include <QPushButton>
#include <QMainWindow>
#include <QVBoxLayout>

class TestWindow : public QMainWindow
{
public:
    TestWindow(QWidget *parent = nullptr) : QMainWindow(parent)
    {
        QLineEdit* le1 = new QLineEdit;
        QLineEdit* le2 = new QLineEdit;

        QPushButton* pb1 = new QPushButton("One");
        QPushButton* pb2 = new QPushButton("Two");

        pb1->setFocusProxy( le1 );
        pb2->setFocusProxy( le2 );

        QHBoxLayout* l1 = new QHBoxLayout;
        l1->addWidget(le1);
        l1->addWidget(pb1);

        QHBoxLayout* l2 = new QHBoxLayout;
        l2->addWidget(le2);
        l2->addWidget(pb2);

        QVBoxLayout* l3 = new QVBoxLayout;
        l3->addLayout(l1);
        l3->addLayout(l2);

        QWidget* w = new QWidget;
        w->setLayout(l3);
        setCentralWidget(w);
    }
};

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