Thanks for your reply.

This seems to have improved the situation somewhat, as I can now see the red image when I click. However, the original image seems to be overlayed over the top of the red image with a level of transparency. It's almost like the visible: false parameter is changed when the MouseArea is clicked?

It's somewhat hard to explain, hopefully the above makes sense?

If not, I can put together some screenshots to demonstrate the issue?

EDIT: Never mind, it looks like user error after all! I had the z-order configured incorrectly, so the drop shadow was being drawn on top of the image rather than underneath it. Thanks again for your help!

Assuming you have an OpenGL context and you can draw/create objects in it you would make that context current, then create a QOpenGLPaintDevice and use it to render() the widget into that. Please note that a widgets require a QApplication instance and a running Qt's event loop, so you would need to ensure you have that.

As for DirectX Qt doesn't have any direct support for it, but you could probably grab() a widget into a QPixmap, transfer the pixels to a DirectX texture and draw a quad with it.
If you feel adventurous you could also implement your own QPaintEngine, then subclass QPaintDevice to return that engine and use it like with the OpenGL version.