Sliding windows and sliding doors are prone to intrusion. There is now a wide variety of hardware to solve this problem. Hockey sticks are a good first line of defense, but there are things that are much better and more discrete.
Most important is probably the spacer wedges that can be placed above the sliding section, preventing anyone from lifting the door or window out of the track without first unscrewing the wedge, which can only be done from the inside.
Then there are all kinds of easy to install pegs or locks that stop the door or window from sliding.
All the items shown were purchased at a regular renovation centre.