Galaxy Note 10.1 : use two windows[apps] in one screen, multitasking mode like before?

[lse123]

Samsung Galaxy Note 10.1 (2012-2013)

I have this tablet, all well and good till upgraded to 4.4.2.

from there on I am lost and i cannot(I do NOT know how) use two windows[apps] in one screen, multitasking mode like before?
Is it still exist this functionality?