A frame ladders are placed on window frames walls the works,I used one years ago and hated it, I use normal pro ladders, saying that I see many window cleaners doing trad with these ladders they place the A on the frame and up they go, weather that is safe or not I would not know as I really don't laders to much as mostly wfp. they are good for harder to reach places that Stan cant reach (debatable) but saying that I would rather do the lot from the floor quciker and safer imo.
I would scan youtube you should find better answers there and can see first hand, I do have a single pointer, fine for small works, not sure I would trust at height but many do.
Sry not much help.
Ian