Option "B" (Bar option) is also applicable to ntuples/trees.
However, while looking at the problem, I see that the bar width
and offset are taken from the current style and not from the ntuple
object.
So, to activate this option you must do:
Root > gStyle->SetBarWidth(0.5); // or any other value <1
Root > ntuple->Draw("x","","B")
To change the bar fill area color, do before ntuple->Draw
Root > ntuple->SetFillColor(2); // this will set bar color to red
I will modify the code to take the barwidth and offset from
the current ntuple instead of teh current style.
Rene Brun