Look...I get it. Modern windows are amazingly efficient, and one reason is that they are no longer separated into small panes. That makes them much better insulators...and ugly looking. So the answer was fake slats? I think they are called mullions (maybe), which is faintly creepy in its own right.

But the wonderful technology of modern windows has failed the mullion industry! The damned things attach using stupid little metal clips that fall out when the window frame flexes...from wind pressure or expansion or contraction. And then the mullions fall out.

We can put a man on the moon and keep Joe Biden ambulatory...but we can't design a mullion that stays put?