After a traumatic weekend wherein Leonard didn't come home after busting out in the middle of the night and I had to put up posters, he was a grounded kitty. I carefully didn't open any window more than an inch and a half, because no screen can hold him, and managed to keep him in for two nights. But last night he *pulled the upper window down*.
The annoying thing is I heard the thump and came running in, but I thought he had just bumped the lower window shut.
I don't think there's anyway to keep him in, not in an unairconditioned apartment.