For dealing with screens on a ladder I use a small spring loaded clamp (any hardware store). I tie the clamp to a small twine or rope and tie the other end to the ladder. I clamp off the screen while I'm working and just let it hang. That way I have my hands free and don't have to run up and down the ladder to set the screen down. I also use a "bucket on a belt" to hold my scrubber and squeege. Tool belts are a must for ladder work.

Rick Kadletz
Mid Missouri Window Cleaning LLC
www.mmwindowcleaning.com