Android Window.fullscreen is not full screen

import QtQuick 2.4
import QtQuick.Window 2.2
import QtQuick.Controls 1.3

Window {
    visible: true
    id: mainWindow
    Rectangle {
        height: parent.height
        width: parent.width/2
        color: "#f0f"
        MouseArea {
            anchors.fill: parent
            onClicked: mainWindow.visibility = Window.AutomaticVisibility
        }
    }
    Rectangle {
        height: parent.height
        width: parent.width/2
        x : width
        color: "#ff0"
        MouseArea {
            anchors.fill: parent
            onClicked: mainWindow.visibility = Window.FullScreen
        }
    }

    visibility: Window.FullScreen
}