mapTo/FromItem() and contains() are non-intuitive to use together

import QtQuick 2.0

Item {
    width: 400; height: 400

    Rectangle {
        id: greenRect
        color: "green"
        width: 50; height: 50
        anchors.centerIn: parent
    }

    MouseArea {
        anchors.fill: parent
        onClicked: {
            var pos = mapToItem(greenRect, mouse.x, mouse.y)
            console.log("pos", greenRect.contains(pos)) // always true, no matter where you click (no error generated)
            console.log("myPoint", greenRect.contains(Qt.point(pos.x, pos.y))) // true only when clicking within the green rectangle
        }
    }
}