Ever heard of “Rube Goldberg”? There is no logic to some things, or the logic may seem obvious to the originator, but be a total mystery to everyone else. Me? I can’t fathom why they make computers and their programs so complicated, but maybe it’s just the old dogs new trick theory. You figured it out, now will you pass that info. on to the next owner, or let 'em figure it out like you did?
Apologies for my misdirection last night-glad you’ve gotten good information and a solution to the problem.
To answer the ‘why’ question-it’s because every window manufacturer does things a little bit differently. If manufacturer B wants to make a window similar to manufacturer A’s product without patent infringement, they need to effect “changes to the art” which can be quite subtle. (and frustrating as hell to the end user)
When I install new windows, I give the customer literature and review operation, but there’s no guarantee that the data will be passed on to owner #2 or beyond.
From my experience in software design, I have a theory: The screen maker realized that there was a flaw to the basic design. Rather than redesign the whole thing from scratch, they make a little tweak here, then a little tweak there, still doesn’t work, so they put a pin here, a spring there, and so on. Finally, it “works.”