Constantly getting QWindowsWindow::setGeometry: Unable to set geometry warning

Since I migrated from Qt 5.6.0 to Qt 5.12.0 I get tones of message reporting setGeometry failed. This is even reported for a very simple program opening a QDialog:

main.cpp:

#include <QApplication>
#include "mainframe.h"
#include <qDebug>

void MessageOutput( QtMsgType type, const QMessageLogContext &context, const QString &msg)
{
    qDebug() << msg;
}

int main( int argc, char* argv[] )
{
    QApplication app(argc, argv);

    qInstallMessageHandler(MessageOutput);

    MainFrame wnd;

    wnd.show();return app.exec();
}

mainframe.h:

#include <QMainWindow>

class MainFrame : public QMainWindow
{
    Q_OBJECT

public:
    MainFrame();

public slots:
    void showPopup();
};

mainframe.cpp:

#include "mainframe.h"

#include <QDialog>
#include <QLabel>
#include <QPushButton>
#include <QVBoxLayout>

MainFrame::MainFrame()
{
    QPushButton* pTextButton = new QPushButton( "Show popup", this );
    connect( pTextButton, SIGNAL(clicked()), this, SLOT(showPopup()) );

setCentralWidget( pTextButton );
}

void MainFrame::showPopup()
{
    QDialog dlg( this );
    dlg.setLayout( new QVBoxLayout() );
    dlg.layout()->addWidget( new QLabel("popup message",&dlg) );
    dlg.exec();
}

Under Windows 7, this reports warning:

QWindowsWindow::setGeometry: Unable to set geometry 132x30+682+303 on QWidgetWin
dow/'QDialogClassWindow'. Resulting geometry: 132x42+682+303 (frame: 4, 28, 4,
4, custom margin: 0, 0, 0, 0, minimum size: 116x42, maximum size: 16777215x16777
215).