You can put things on the inside of the window. Just don't use pins, thumbtacks, etc and make holes in the window wood or peel off the paint. There isn't an outlet outside the villa like at OKW, so you couldn't string lights around the balcony unless you had battery operated lights or left the door or window open with the cord running through the opening. But I wouldn't do that because some people have said that they had kids climbing over onto their balcony.