I have to agree with this one.... It is her house not, if it was a person it would be called 'break and enter' or maybe just 'enter' but you get the point. I would think you would have to keep Teddy inside for now.I guess I’ll be the outlier here. I don’t believe the neighbor should have to change her home to keep your cat out. It would be great if she put a screen in the window and if you offered to assist with that but in my opinion ultimately you are responsible for your cat. If the neighbor pursues the issue you may need to keep your cat indoors to break it of the habit.