Premier League Gameweek 31

What are the white rectangles in front of each dugout for?

I used to think it was the area the managers were allowed to stand in but that's not it (as the managers just go wherever they want without anyone giving a shit).
 
I hate how players stop playing to raise their hand indicating offside instead of playing on and letting VAR deal with it. Shit defending from WH
 
That was beautiful