You cannot set years on date properties in QML

import QtQuick 2.0

Item {
    width: 360
    height: 360

    property date date1: new Date()

    Component.onCompleted: {
        console.log("date1 initial value: " + date1)
        var tmpDate = date1
        console.log("tmpDate initial value: " + tmpDate)
        date1.setUTCFullYear(1000)
        console.log("date1 1000 year value: " + date1 + " (unexpected result!)")
        tmpDate.setUTCFullYear(1000)
        console.log("tmpDate 1000 year value: " + tmpDate)
    }
}

qml: date1 initial value: Fri Dec 12 14:06:50 2014 GMT+0100
qml: tmpDate initial value: Fri Dec 12 14:06:50 2014 GMT+0100
qml: date1 1000 year value: Fri Dec 12 14:06:50 2014 GMT+0100 (unexpected result!)
qml: tmpDate 1000 year value: Fri Dec 12 14:06:50 1000 GMT+0100