DialogButtonBox align to right incorrectly when using a single standard button

import QtQuick 2.7
import QtQuick.Controls 2.5
import QtQuick.Window 2.2

ApplicationWindow {
    id: window
    visible: true
    width: 640
    height: 480
    title: qsTr("Stack")

    Dialog {
        id: dialog
        title: qsTr("About")
        modal: true
        focus: true
        visible: true
        width: 400
        standardButtons: Dialog.Ok
    }
}