SetFillColor overwrite any color but not white

ROOT
1

With this code it seems that TGraph::SetFillColor overwrite the gStyle->SetFillColor option only when gStyle->SetFillColor is different from kWhite. Why I cannot overwrite the white?

import ROOT
import numpy as np
ROOT.gStyle.SetFillColor(ROOT.kBlue)
#ROOT.gStyle.SetFillColor(ROOT.kWhite)
gr = ROOT.TGraphErrors(10, np.arange(10, dtype=float), np.arange(10, dtype=float),
                       np.zeros(10, dtype=float), np.ones(10, dtype=float))
gr.SetFillColor(ROOT.kRed)
gr.Draw("AL3")

in fact if you uncomment the line the fill color of the TGraph is white.

2

#10 = “white”; “kWhite” = 0 = “dummy / none” (a “bug” I would say but others might claim it’s a “feature”)
ROOT.gStyle.SetFillColor(10)