Qt5 embedded system dialog message box position problem

Qt5 embedded's dialog message box's postion is not at the center of the screen.

We set the content show in vertical in the screen rotation, but the pop up system dialog message box is not at the center position.

The expect is dialog message box is at the center of the screen.

We confirm this problem at Qt 5.6.2 and Qt 5.9.3.

The test is easy to press an button and pop up a system dialog as following picture in the attached file.

Test Code:

QMessageBox::Yes == QMessageBox::warning(this, tr("警告"), tr("メッセージ"))