So, I discovered that my new addition can get his head and shoulders through the railings on my second floor condo balcony (I didn't give him a chance to get any further). I don't think he'd jump, but he gets really excited when he sees the downstairs neighbor's dog go out the front door. Is there a kind of mesh/webbing lining that anyone has had success with? Any other ideas? I'm in a historical building, so I cannot make any drastic changes to the exterior. Thanks