TextInput's xToPosition() does not work when there's more text than fit in the field

import Qt 4.7

Rectangle {
    width: 640; height: 480;
    Rectangle {
        anchors.centerIn: parent
        width: 400; height: 25;
        color: "blue"

        TextInput {
            anchors.fill: parent
            color: "white"
            focus: true
            text: "Sea Shepherd campaigner Peter Bethune faces 15 years in jail after boarding whaling ship"
            MouseArea {
                anchors.fill: parent
                onPressed: parent.cursorPosition = parent.xToPosition(mouse.x);
                onPositionChanged: parent.moveCursorSelection(parent.xToPosition(mouse.x));
            }
        }
    }
}