Folks at XDA have ported the multi window app from Galaxy note 2 to Samsung Galaxy Grand Quattro phone. To get it on your phone, you must have a rooted phone and also should have CWM recovery installed on it.
1) Download this file and put it on your phone’s SD card. Now, reboot to cwm recovery (vol down + power)
2) Select, “install my zip from SD card” and select the file.
That is it. You have successfully downloaded and installed Multi Window on to your Galaxy Grand Quattro phone.