Because this is an override it will remove snapping on all windows/curtains – both EA and CC.
If any other non-curtain/window CC in the game uses the curtain slotting, it will also disable those. You might think, why would anything else use curtain slotting? Before EA added all those fancy new features I had to get creative and, in fact, my initial closet/clothes system did use curtain slotting. So make sure you have gotten the new & improved closet/clothes sets BEFORE installing this override.