In my experience with QtQuick within multiple projects, there is need to custom clipping using a custom shape not rectangle.
Currently it is possible to do that using shader (OpacityMask) or Canvas which both is not very efficient and clear ways.
I tested `QSGClippingNode` but it just clips children `QSGNodes` not children `QQuickItems` .
I'm suggest to develop an Item for QML named `ClipperItem` which clips all children `QQuickItem` with a custom shape.