Actually it looks pretty good, and since you were sparse with the actual window-opening description it more or less checks out (spoken with the experience of someone whose older brother legitimately used to have to climb two stories up and swing through a window to access our own house at times due to issues with busted security locks, so yeah XD) The only question is how quickly people will figure out he's gotten in and how hard Damian throws the batarang at him/and or attacks him with a broom.