Some Material controls do not respect Material.background

import QtQuick 2.5
import QtQuick.Window 2.2
import QtQuick.Controls 2.0
import QtQuick.Controls.Material 2.0

ApplicationWindow {
    id: window
    width: 360
    height: 360
    visible: true

    Material.background: "#ccc"

    header: ToolBar {
        Material.background: "red"
    }

    Popup {
        Material.background: "red"

        visible: true
        x: 60; y: 60
        width: parent.width - 120
        height: parent.height - 120
        closePolicy: Popup.NoAutoClose
    }
}