Transparent region to show external application

[lartimus]

Re: [SOLVED] How to draw a transparent hole inside a QQuickView / QQuickWindow based on a custom QQuickItem?
@mlong I am trying to design a QtQuick application that will run under Linux and has a transparent region that will show an unrelated background application. When I try your suggested method, the region is black and opaque, so I can't see my background application.