2 questions on "colz" option: under/overflow color

ROOT
1

I am using root 5.14 on Mac OSX. In my macro I draw a TH2D with explicit maximum and minimum values set, and see that the under/overflow bins are not drawn (they are white, while I am using pallet ‘1’). Is there any way to set the under/overflow color with option ‘colz’?

This is a weighted histogram, with weight values going negative, and the colz range reflects that correctly and the plot is drawn correctly. However, I notice that bins with no entries (ie ones never touched by a ‘Fill’ call) show up with the color associated with weight value 0, as opposed to not being drawn. According to previous postings (see root.cern.ch/root/roottalk/roottalk04/0641.html ) the statement was clearly made that empty bins will not be drawn with ‘colz’ (ie should show up as white). I would greatly prefer that empty bins simply not be drawn, is there a way to distinguish that from the weight value ‘0’ so they are not drawn? I tried invoking Sumw2 before filling, but that didn’t work.
thanks, Dave Brown :question:

2

Bin with content 0 are considered as empty if all the histogram bins’ content is >=0. In that case the empty bin are not drawn. You can color them using:
c1->SetFrameFillColor(TColor::GetColorPalette(0));
If the histogram has some negative bins, the bins with value 0 are drawn as any other bins.