I'm just paranoid about this.
When I'm home, all the windows are wide open. I love fresh air and sunshine, but when I leave for work, I have to shut them, well, not all the way. I leave about a 6 inch gap. Then I put the locks on them. I'm just always so paranoid that some prankster kids will come along and slit the screen to let them out or that somehow they'll push against it and get out. I push on the screens all the time when I'm home to make sure that they're sturdy......I guess I just overreact.........They love to sit in the windows....I hate doing that to them.........