Custom pointMarker can't access outside the component

Steps: Modify ScatterProperties example to bind properties outside the pointMarker, for example:

pointMarker: Image {
                property bool selected: false
                source: "images/happy_box.png"
                width: selected ? 96 : background.radius
                height: selected ? 96 : 64
            }

And you get error: qrc:/qml/testbed/ScatterProperties.qml:80:17: ReferenceError: background is not defined

With QML Loader and Repeater this works, so you can bind to other elements properties. Is this some simpler fix to create components into correct context / call some componentComplete once created? Or should we utilize "qquickrepeater_p.h" for the correct behavior? Custom bars misbehaves similarly so this is needed in other places too.