GridLayout in another GridLayout

[Kiichiro]

I have this code:
@
import QtQuick 2.1
import QtQuick.Controls 1.0
import QtQuick.Window 2.0
import QtQuick.Layouts 1.0

Window {
title: qsTr("СЦМ Концепт")
color: "blue"
width: 1920
height: 1080

GridLayout {
    id: grid_layout1
    anchors.fill: parent

        GridLayout {
            id: grid1
            Layout.fillHeight: true
            Layout.fillWidth: true
            width: 2

            Rectangle {
                Layout.fillHeight: true
                Layout.fillWidth: true
                color: "red"
            }

            Rectangle {
                Layout.fillHeight: true
                Layout.fillWidth: true
                color: "green"
            }
        }

        GridLayout {
            id: grid2
            Layout.fillHeight: true
            Layout.fillWidth: true
            width: 1

            Rectangle {
                Layout.fillHeight: true
                Layout.fillWidth: true
                color: "red"
            }

            Rectangle {
                Layout.fillHeight: true
                Layout.fillWidth: true
                color: "green"
            }
        }
}

}
@

And I get this picture:
http://imgur.com/nq6jbH6

But if I write this:
@
import QtQuick 2.0
import QtQuick.Controls 1.0
import QtQuick.Window 2.0
import QtQuick.Layouts 1.0

Window {
title: qsTr("СЦМ Концепт")
color: "blue"
width: 1920
height: 1080

GridLayout {
    id: grid_layout1
    anchors.fill: parent

    Item {
        Layout.fillHeight: true
        Layout.fillWidth: true
        width: 2

        GridLayout {
            id: grid1
            anchors.fill: parent

            Rectangle {
                Layout.fillHeight: true
                Layout.fillWidth: true
                color: "red"
            }

            Rectangle {
                Layout.fillHeight: true
                Layout.fillWidth: true
                color: "green"
            }
        }
    }

    Item {
        Layout.fillHeight: true
        Layout.fillWidth: true
        width: 1

        GridLayout {
            id: grid2
            anchors.fill: parent

            Rectangle {
                Layout.fillHeight: true
                Layout.fillWidth: true
                color: "red"
            }

            Rectangle {
                Layout.fillHeight: true
                Layout.fillWidth: true
                color: "green"
            }
        }
    }
}

}
@

I get right resulte:
http://imgur.com/lWNNOtx

Is this a bug or maybe I do something wrong? Why I should place second GridLayout inside a Item?