palette.brightText is undefined

import QtQuick 2.10
import QtQuick.Window 2.10

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    SystemPalette { id: pal }
    Rectangle {
        color: pal.brightText
    }
}

qrc:/main.qml:11:16: Unable to assign [undefined] to QColor