We live on the top floor of a three story bldg.
Although I have installed a cat screen on our large sliding patio door,
I never leave the sliding door open when I am gone.
I do leave it open if I am home and alert to their sounds but I keep a close eye on them.
One kitty in our bldg. fell a couple of years ago,
I won't take that risk.
I never leave my bedroom window open...
They could fall straight down.
One of their cat trees is located right in front of the patio window...
they love it there.
They have a tall desk to perch on at the bedroom window.
Sadie & Dexter, given enough time can open anything.
Better safe than sorry.