Hi and welcome!
I will speak from experience- cats will do whatever they want. If you can successfully train her to stay out of the window, chances are, she will get up , there when you're gone. Cats are like that- dogs are different.
My mother lives in a small one room basement apartment which has 2 windows besides the door. Her cat Mama is not allowed in either window bc my mom thinks cats shouldn't be jumping up off the floor. She barred both windows so the cat cannot jump up there.
Mama is obscenely obese, lazy and acts deprived of attention. She is a needy cat and her exploratory desires are "not allowed". As a result, when my mom comes over and see's how cat-like Oliver is she wants to trade cats.
In my experience and opinion, you should not deprive a cat of these things. Keeping an indoor cat requires special attention to entertainment since they cannot go out and hunt and stalk outside. A window is the closest thing a cat has to the fascinating outside world. I don't recommend closing your cat from that.
If you are sneaking a cat into a condo I would suggest snooping around to see if anyone else keeps pets. Try to see how picky they are on keeping one cat. You probably will not be able to hide her for long for a number of reasons.
- she might meow or cry or make other sound
- she might get out the door when your coming in
- people might smell her litter as it goes in the trash
- she will get in the window
- people will see cat fur on you.
there is a spray at most petshops u can get that u spray around the area that you dont want your animal going, iv used it in the past it HAS NOT worked for my cats as they do as they please, but you are more then welcome to try it.
Still the best permanent solution is look for pet friendly place. The effort of hiding him plus thinking how others not discover him plus meeting his need is just greater than a place that welcomes him..