Some of your friends probably know when you're invisible.

Long story short, I've got a friend who won't take no for an answer and my only safe "escape" is to appear offline. Well, oddly enough he found out how to see when I'm online even after I appeared offline. I looked up how tf he did this and this was all I could find:
https://www.youtube.com/watch?v=1CS68J602xs

It still works, I've tested it myself. Any chance on this being fixed? Kinda defeats the purpose of appearing offline when you have loopholes like this.