No tab and on the right of what? I look in under Settings -> Display-> and Multi window setting is grayed out and checked?
Maybe I'm confused
~ScottGeek.
When I hold the back button I get the pop-up and when I click OK the multi-window panel opens. To open it on any screen I flick from the right edge of the display (kind of a tricky motion, especially on the home screen, you have to come off the edge to avoid scrolling to the next home screen). My option for multi-window is not greyed out, this may be your problem. This was an issue I had with the upgrade from 4.1.2 to 4.2.2. I had to do the dreaded factory reset to fix it but others that had the problem back then may have posted a better fix. Search for this problem with that upgrade and see if a better option finally surfaced.
You might try this, it's a post from the Note 2 forum but the process should be similar since it is a Samsung device
To clear the system cache (root not needed) do the following (it will NOT affect any personal data, it's only a temporary cache area used by the Android OS. Clearing it periodically can improve system performance):
- With your Device off simultaneously press and hold Volume Up/Home/power buttons until you see Android System Recovery at the top of the screen and a green android laying down with a Red triangle above him in the center of the screen.
- Scroll down using the Volume down button and Highlight "wipe cache partition" and press the power button to select
- When it says Cache wipe complete at the bottom and "reboot system now" is highlight press the power button to reboot.