NEVER TILT THE WINDOWS OPEN.
Tilted windows can be a deadly trap for cats.
A cat can become trapped, suffer severe internal injuries and die.
Also doors, especially in the wind. A much loved cat we sat for died from internal injuries when a door blew shut as she was walking through it. Not on our watch fortunately but still traumatic.
This is such important safety advice @Jac 
thanks for the reminder so that we can keep our furry feline friends safe!