If the contact is at the bottom of the window you cannot "vent" the window. That is have it 4" open and still be protected. Some people like to sleep or go to town with the windows cracked for venilation. Also, if you are in an area with lightining, the reed switches can be welded closed from the induced current of a nearby lightning strike, meaning the contact will not open when the window opens. This is a problem with hardwired contacts. You could consider wireless transmitters. Caddx (GE) control panels use ITI (also now GE) wireless transmitters. They have a five year battery life from one 1/2 AA lithium battery and a range of a couple hundred feet easily. They would be easy to mount on vinyl windows with 3M double sided tape and silicone so no warranties are voided, no leaks and with two magnets the window can be left open a few inches and still be protected. Or just forget about the window itself and install an "alarm screen" with the wireless transmitter inside the room and the window can be left wide open with full detection capabilities if the screen is removed or cut. If you use tampered wireless transmitters on a "day loop" it will also keep teenagers inside their room at night. No sneaking out after everyone goes to bed.