Cannot change application cursor if WebView is beeing used

I'm writing an application like a media player but with HTML content. After some time of inactivity I'd like to hide the mouse cursor.

The following code does not work as expected.

import QtQuick 2.1
import QtQuick.Controls 1.0
import QtWebKit 3.0

ApplicationWindow {
    title: qsTr("Hello World")
    width: 640
    height: 480

    WebView {
        anchors.fill: parent
    }

    MouseArea {
        cursorShape: Qt.BlankCursor
        acceptedButtons: Qt.NoButton
        anchors.fill: parent
    }
}

I'd expect the MouseArea to override the WebView, but instead the cursor is still always shown. If I remove the WebView, the cursor is properly hidden.

Also I've tried setting the cursor using QApplication::setOverrideCursor(QCursor(Qt::BlankCursor)); but it doesn't work as well.