Default samsung tab 3 7.0 sm-t210r

so i recently bought the galaxy tab 3 it showed it came with multi window on it then guess what it doesnt the sprint one does i bought this tablet for the one feature alone i have tried everything and cant get it going i am rooted and i have a custom recovery can someone help me with this all i care about is its abillity to have multi window enable if u know any roms u can post link to anything thank you