centering with margin

import QtQuick 1.0


Rectangle {
    id: outerRect
    width: innerRect.width + 20;
    height: innerRect.height + 20

    color: "lightblue"
    Rectangle {
        id: innerRect
        anchors.horizontalCenter: parent.horizontalCenter
        anchors.verticalCenter: parent.verticalCenter
        width: childrenRect.width
        height: childrenRect.height
        Row {
            id: innerChild
            spacing: 10
            Rectangle {
                width: 100
                height: 100
                color: "red"
            }
            Rectangle {
                width: 100
                height: 100
                color: "green"
            }
            Rectangle {
                width: 100
                height: 100
                color: "blue"
            }
        }
    }
}