cat obsessed with playing with window latch string, advice?
So my cat (he's orange and sterilized) is obsessed with playing with a thickish string that's attached to the wall to keep windows open. He doesn't want to grab it (we tried to swing it in his face, but he had no reaction) he wants us to wave the string through the glass of the window while he paws and jumps at the glass. We tried with the window open so he can grab it. He doesn't like that. Now he's staring longingly at the still string (because we're the one making it move) hoping it will move on its own. He doesn't want to play with any other toy he has or loves. Tried with yarn, with fish toy, string toy, but no, he wants that specific string through the glass. I'm worried he'll get frustrated if we continue to let him play through the glass since he's not grabbing anything and can't play out his natural behaviors. Any advice?