When there's a window in a room, you can see player characters move in and out of the rooms it views into. However, when you're busy doing things, or maybe just tired, it's sometimes hard to tell what's happening through a window, and what's happening in the room you're sitting in, leading to unfortunate things like jumping out of your skin when a character appears to walk through a locked door, and past you further inside, only to realize after searching that you missed the "through the window" flag in front of that action being performed.
I think it might be helpful to flag when something happens through a window in a more notable way, so you can't confuse something happening outside for something happening inside. Something as simple as making "Through the window" a different color would do.