I have 1 large house with the same type of window, wooden windows with a strip in the middle, and water runs down the back of them.
Now I'm traditional, and have decided to change to wfp, the last time I did them, I was looking for away around it, I couldn't see any way at all, but to continue this paticular house with the traditional method.
Unless someone can come up with a better way, to do this type of window then Ladders it is.