[mook]

Specifically, it can access screen content, but not window content. As in, passing in the desktop hwnd gets you a picture, passing in a different hwnd gets you a bunch of black. At least as of when I tried it a few months ago on Windows 10.

[bjc]

I was curious about this so I just tested it... some windows are able to be captured and some are black

[willvarfar]

Does the screen content contain all the windows that are visible, or is it the desktop image?

[mook]

All of the windows visible on screen. For my use case, I was taking a screenshot of my app (for automated testing), so I ended up taking a full desktop screenshot and cropping it to the window.