Here is one solution:
https://shelleyswanland.com/2009/07/...-window-quilt/
here's another- (scroll down to find the red and white CW):
http://boltonphoenixtheatre.com/wind...make-your-own/
Actually, looking at Google images, it looks like most are just sewn down:
https://www.google.com/search?q=cath...EIXzAD#imgrc=_
This link shows the "triangle" problem. (scroll down)
https://www.colorwaysbyvicki.com/cat...dow-quilt.html