> Do you mean this?
Yes, exactly !
> Of course there is no window violation because the black "window" is a fake. The real window is the white one
I would disagree with this. The white area shows the total image area. The "window" is located within that area.
Many years ago, my mentor Pompey Mainardi pointed out to me something very important: The stereo window is as much an "object" in space as any of the other elements in your composition. Once you understand that, you can play with that "frame" any way you wish and in fact, use multiple frames.