I was watching a live stream of someone playing a game and noticed that when he dragged an item from his primary monitor to his secondary monitor (and left it idling on that screen) the icon would remove itself from his taskbar. Tried googling around and could not find the answer on how to replicate this. any ideas?
edit: to clarify a little further i'm not refering to the system tray. refering to the actual task bar icons that show open programs like firefox/Gchrome/Thunderbird etc.