Well I was rping with some one, accepted them as a friend, went ot move it a bit instead of just closing it and well, this ended up happening.
Usually people don't drag the "Server Response" titled windows around and just close them.
The titled ones shouldn't do this, such as the actual Friends List itself.
It will only be an issue if you keep adding friends/it bothers you/you don't refresh the page.
A simple refresh will align it back to normal.