MouseArea mouseX/Y not reported under Scenegraph unless mouse is pressed

Running the attached qml in qmlviewer and qmlscene shows two different behaviours. The Text element shows the values of hoverEnabled, containsMouse, pressed and mouseX,mouseY respectively.

In qmlviewer, the text shows Box the mouseX and mouseY co-ordinates regardless of the value of pressed
In qmlscene, the text shows Box the mouseX and mouseY co-ordinates only if the value of pressed is "true"

The documentation states:

If hoverEnabled is true then these properties will be valid when:

    * no button is pressed, but the mouse is within the MouseArea (containsMouse is true).
    * a button is pressed and held, even if it has since moved out of the area.