I have no green arrow and I do not ever recall seeing a green arrow. Maybe your grid is not large enough? Move the mouse toward the bottom of the grid. See image with crudely made 1. Also look at what I circled with a 2 and click those icons to see what it does to your screen. 

I will also note that the PINK is an option in settings to give some clear idea of what item you are on and the alternating white gray is also a display option.