Is this issue with the painting really a bug though? It is different than the other paintings, but all the same, none of them were really intended to be placed over a window...
I have no idea
Why CAN we place them over windows in the first place ? It's odd.
Well, we can place any type of wall décor over or partially over windows, and I *think* it's been that way since the beginning. I think the game must treat the walls as if they were still blank, even when a window is added, in terms of object placement. This may have been necessary in order to allow curtains to place properly... I don't know; a dev would have to comment, but I personally wouldn't change the functionality as it allows for more creative options, although I suppose they could gate it behind bb.moveobjects.
Maybe we can get some insight
