If Volume is less then the previous 20 intervals, Volume is gray. If Volume is greater then the previous 40 intervals, Volume is black. If Volume is less then the previous 2 intervals, Volume is purple. If Volume is less then the previous, Volume is red. If Volume is greater then the previous, Volume is blue. Other - white.
You can add on the indicator a 2.5 Standart Deviation of a 20 period Bollinger Band Shifted 3 periods forward.
COuld you fix the bug in Hidden gap volume for MT4... there is a color bug and refresh issues