[mikewhy]

> If I'm understanding you correctly, that means there's already a supported workaround for this if apps just use that API?

I don't think this API helps people that use display out, like a projector or screen.

[nightpool]

Why would you think that? The CGDisplayCapture function that the GP linked includes a "display ID" keyword to specify a specific external display, like a projector or a screen. Why wouldn't it work?