Functionality over looks!
The top hung system is built more functionally than aesthetically. By leaving the window open, it allows for ventilation, yet shields against the rain and provides shade (depending on glass type).
A limiter can be added to restrict the opening so it would be difficult to climb in and out of the window, keeping the security of your home intact.
This is commonly used in the bathroom, storeroom or kitchen, where ventilation and comfort are prioritised. One can choose between frosted glass, opaque glass or even smart glass for added privacy!