ApplicationWindow: warning on resize

1 - run:

import QtQuick 2.1
import QtQuick.Controls 1.0

ApplicationWindow {
    width: 640
    height: 480
}

2 - resize the window

=> the following warning is generated:

QQuickItem: Cannot set activeFocusOnTab to false once item is the active focus item.

It happens on Ubuntu. Not on Windows though.