Multi window is disabled after upgrading from 4.1.2 to 4.2.2 Multi-window icon is disabled after upgrading samsung galaxy tab from 4.1.2 to 4.2.2.

 
Screenshots (click images for larger variants)

Anybody fixed this problem ?
Any idea how to fix this without doing a factory reset ?
A factory reset seems to work for some people. You might want to back-up your files / data before doing this.

Source: Problems with Jelly Bean 4.2.2 update