A passage that stood out to me was on page 378, where the narrator describes first seeing his cousin again. Two quotes are: "I came down the street where my cousin's corner window can be seen from a considerable distance." and "As I came closer, I noticed that my cousin had put on his fine Warsaw dressing-gown and was smoking tobacco in the Turkish pipe he used on Sundays."
After reading the whole short story, where the narrator and his cousin are looking out of the window, it struck me on rereading it that quite a bit can also be seen by looking into the window. The first quote shows us both that the cousin's field of view from his window is quite wide (this is said several times in the text), but also that his window is not hidden and can be seen quite easily. As we can see in the second quote, much can be seen in detail through the window, such that it is not just possible for observation to move one way out of the window but also to move into the window. The only thing that seems to prevent most people form looking up at the window and seeing that they are being watched is that they have no reason to, whereas the narrator was able to see his cousin quite easily because he presumably looks for his cousin's window whenever he is passing by.
Observations:
Throughout the text colors are used as focal points. Ex. cousin's red cap, lemon-yellow cloth, white apron, etc.