Do you mean brightness slider? Like in touchwiz roms?
Maybe you can explain bit more?
No, I mean the automatic brightness. For example, cover the brightness sensor with your hands, and turn it on. The screen will be dark. Now, let some light reach the sensor - the brightness will change instantly, without any transition or animation.
Do the same with, for example, PAC 4.2 - the brightness change will have a transition. It wont change from 0 to 100% instantly, it will go through every percent in a second I think - so it looks cool. Stock 2.2 did this too, and some CM9 and CM10 (maybe PAC CM10, I don't remember) too.
Alternatively, you can test it with the brightness slider: set it to the lowest value, then to the highest. If you see a transition, not an instant 0 to 100% change, it works.
Edited by ziyan, 26 March 2013 - 02:52 PM.