Window guard for 3rd floor apartment
 

I've never had to think about this before but due to the lay out of our apartment the couch has to be against the wall that the windows are... its a MUST to have the window(s) open as the afternoon sun heats our place up like an over (very strange occurrence for Seattle I know). Holly has now got a fascination with standing on the window ledge and just observing what's going on outside, we are 3 stories up and it concerns me that she could push on the fly screen and perhaps break it and fall to her death.. I've pushed pretty hard on it and its fairly sturdy but I'm not willing to put it to the test ....

I've been looking online foe "window guards for dogs" and have found a lot that you can install in your car .. some are expandable to fit in the car window and you wind the window up to secure it to the top of the door ... the only place I could find was a company that claims to make new window screens for you to replace what you have that are "almost" pet and child proof (this is what it says on there website) .. as we rent I'd rather get something that I can put up and down when needed and take with us when we move .....

Any suggestions here would be awesome .. I'm fresh out of ideas

cheers

This looks like a possibility. Removable, easy to install, fits a wide variety of size windows.

Mr. Goodbar - The Original Home Security Bars

What about those screen protectors you can get at Lowes or Home Depot? You have to screw them into the window screen frame, but it shouldn't damage it much. This is what I'm thinking about. I used it on my sliding door since my poodle liked to try to walk thru them.
Amazon.com: M-D Building Products 33381 19-Inch...

Great ideas .. its given me some hope in finding something .. thanks so much :-)