Technically I'm sure it's possible, I've seen programs that have a kind of frosted see-through look. But that's something the program has to implement.
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It’s possible at the application level for Qt stuff at least, iirc you just pass a window arg to enable transparency. If you mean from like a user settings perspective, idk sorry 😂
Could you grab the desktop background image, then do some trickery rendering the image using the window position to pan and crop it?