Slide / lift and slide

[Oz07]

Rear elevation on our new place is planned with 2 modest sliding patio doors and a single standard door on the utility. Is there a way to have the sliding doors slightly open but secure? I know back in the day we used to put a stick in the bottom rail as a sort of dead lock. I know in oz they have secure fly screen doors in front of the glass sliders. I am just wondering how I can leave the doors slightly open to get some air in for night purging etc while still having it secure. 

[Russell griffiths]

The handle on our lift n slide from norrsken lifts the door up from the lower track, you can slide it open any amount you want 50mm- 1200mm or whatever, then turn the handle and drop the door back down, that’s it, it’s not moving not 1mm unless you pulled it with a truck. 

[ToughButterCup]

As @Russell griffiths above. Gaulhofer 4.5 meter window -open 10mm for the last few days and locked in place,  right next to the dog's cage. 

Why 10mm? 

So the bloody cats can't drop blood-soaked presents off for the dog, just outside her  cage . little sods.