Hi all! As I am more a propmaker than a coder I have to

Hi all!

As I am more a propmaker than a coder I have to ask for help. I am truely amazed by FastLED just a bit short in time atm, and not even sure if it is fair to ask for such help but I have to try.
Any kind of help much appreciated in advance.

The task:
-have to make 20 blocks of LEDs (5pcs/block for example)
and control them with a pot or buttons.
The desired sequence is the following:
-all LEDs OFF
-turn a bit on the pot first block fade in to white and stay ON
-turn a bit more on the pot: first block fade out, next block fade in and stay ON, and so on.
Obviously it has to work the other way around too.

(UNOR3, WS2812B strip)

Thanks again.

@Gergely_Domolki I put a code snipplet for changing animations with a pot here:
http://pastebin.com/iCCDjDPF