Somebody across the street just tried to better the weather [*]
The guy came out about 5 minutes after it started raining and cleaned the outside of the window without any kind of security cord (the window is on the 3rd floor)
[Update]: Now there’s two of them and it works! It already stopped raining! It isn’t quite as spectacular though since the second guy does not dare to come out as far, instead he opens both wings to clean half of the center from either side, therefore no photo.