@Valyar, You aren't doing anything wrong. The issue is the image window itself. The base file that builds the frame has transparency to it. This is used as the mask as well. So, you are correct since it is transparent, any open windows beneath it are visible.
I guess using it depends on the available screen real estate. If someone has very little, I can see this being a muddled issue. It was meant to be a cool image.
I will see if I can rework the mask to be solid, that should help.