Default Android multiwindows help

hi everyone! firstly sorry for my bad english, but i'm italian. i own a samsung galaxy tab 2 7" wifi that i use in my car as navigator, music player with video of the song and for autovelox allarm. i want to know if in any method i can use this 3 app in multiwindows or in popup mode. autovelox app can be run in background mode but i'm interested because there is a 4th app that i want use. so would use , in multiwindows or popup mode, a video player, the navigator, and 1 o 2 other app such autovelox or obd control. my tab doesn't have multiwindows in default option but i read that it's possible to add by using modified rom. if anyone can help me i will very happy. thanks