The histogram on the CC curve reflects chromaticity before the adjustment.
You can use the Show/Hide chromaticity histogram button Histogram-gold-on-small.svg besides the histogram to help you see the effects of your CC curve tweaks on the histogram, and to help you find the maximum value before you start clipping colors.
Screenshots in rawpedia shows that the background histogram keeps constant when CC curve changes. But when I change the CC curve, the background histogram changes accordingly. It seems that the histogram reflects chromaticity AFTER the adjustment?
Running RT 5.8 in Linux.
I read in RawPedia http://rawpedia.rawtherapee.com/Lab_Adjustments#CC_Curve
Screenshots in rawpedia shows that the background histogram keeps constant when CC curve changes. But when I change the CC curve, the background histogram changes accordingly. It seems that the histogram reflects chromaticity AFTER the adjustment?