I have a back room with a pair of computer servers running pretty hot. Would love to leave the window open a crack for ventilation but it's ground floor. Have a spare bedroom on the ground floor where I'd like to do the same thing but with a female friend sleeping there I've got to have good security. If they were sliding windows I could put a piece of dowel in the track with the opening too small to reach around & access the dowel.

Is there an equivalent way to do this with casement windows? They're brand new so I hesitate to drill a hole in the side tracks and slide in a piece of steel rod, which was my first thought. That would void the warranty, no?

TIA - R.