Recently i discovered a bug, that gives you opportunity climbing through the closed windows. It's only work on 2 angles, and when you facing at the window and press right click on the floor of the building. But it doesn't work when you trying this to get out of the building, only in the building.
I recorder it so it would be more understandable. (because i'm from russia, and can make mistakes in my words)
Here's the the video: