Question: How to burglar proof windows?
Best Option: Use true high security windows which were designed, manufactured, and installed with the express purpose of defeating attacks on your building. Make sure the glass is impact resistant, the frames are security grade and the hardware is security grade.
Burglar proof your glass to increase the difficulty for a burglar. Window films make glass a little harder to break, but they do nothing to increase the strength of a frame or hardware.
Install window bars. This is the cheapest approach but has a dangerous downside in potentially trapping a person in the house in case of fire.