How to enable multi window feature on Android 4.3?

How to enable multi window feature on Android 4.3?
Below are the steps with a little tweaks revealed by a user in XDA-developer forum that you need to do to allow you brings up the multi window panel using the Back button:

1. Go to Settings.
2. Tap My Device.
3. Tap Home screen mode.
4. Select Easy mode and then followed by tapping Apply button.
5. Now, go back to the Settings menu.
6. Tap My Device.
7. Tap Home screen mode.
8. Select Standard mode and then followed by tapping Apply button.
9. Now, go back to the Settings menu.
10. Tap My Device.
11. Tap Display.
12. Enable Multi window by ticking the box next to this option. When the box is ticked means this option is enabled.

Resource: http://inside-galaxy.blogspot.com/2013/12/samsung-galaxy-s3-how-to-fix-cant-open.html