Use the simple code below,

import QtQuick 1.1

Rectangle {
    width: 360
    height: 360

    Text {
        width: 100
        height: 30
        id: dummy
        text: qsTr("Dummy")
        anchors.centerIn: parent
        horizontalAlignment: Text.AlignHCenter
        verticalAlignment: Text.AlignVCenter
    }
}

1. Open Designer.
2. Change font size to 24
3. Change font size type to pixel
4. Change font size to 14
5. Save page
6. Change Creator mode to Edit
7. Change Creator mode to Design - font size type = points [Not correct]
8. Change font size to 18
9. Change Creator mode to Edit - pointSize and pixelSize are present on qml code [Not correct]