Sorry for bad English
I tried many roms on my galaxy S3 of course these roms is Samsung TW , i know that AOSP doesn't has this feature ,, but i noticed something that smart stay icon appear normally when i activate it in Smartdroid rom only this rom but other roms not ,, and since our awesome developers ported kitkat on S3 i tried it from (Preview 1 to 5) but i didn't see the icon , and kernel i often use Yank kernel or boeffla kernel ,,, Sorry for bad English.
- set the screen timeout to 15 sec
- Keep looking at the screen (in good lighting)
- if you notice that the screen doesn't turn off after the timeout, then the service is working.
I've had the icon visible all the time but my friend's S3 does not have any icon, yet the service works.