Thanks for the suggestions but there are no screws in the frames from my boat. The plastic straps that you refer to are held in place by indentations stamped in the frame during the manufacturing process. These indentations are consistent with the description of the windows that have appeared in other threads on this topic. Like the others, I have drilled these indentations out and the frame still does not come apart. I have been able to pry one end apart about 1/2 inch but am reluctatnt to force it furthur for fear of bending or gouging the frame. It would be informative to me to learn whether or not others have not experienced this issue and that they simply pulled their apart. Then I would know that I am looking for something unusual and out of the norm. On the other hand, if others have had a difficult time separating the halves of the frame, then it would be helpful to know how they addressed the issue.