[Rivet] Stack= options for *.plot files

[David Bjergaard]

Hi,

I'm having trouble using the Stack option documented here:
http://rivet.hepforge.org/make-plots.html#_plot
Under the subheading "Plotting Options"

Specifically:
>> Stack=<list>
>
> Whitespace separated list of histogram IDs. The histograms will be added
> on top of each other. This is useful for example to compare data with
> background if the background has contributions from several
> histograms.

I've booked my histograms like this:
> _histograms["WJetCharge"] = bookHistogram1D("WJetCharge" , 50, -0.3, 0.3);
> _histograms["QuarkJetCharge"] = bookHistogram1D("QuarkJetCharge" , 50, -0.3, 0.3);      
> _histograms["GluonJetCharge"] = bookHistogram1D("GluonJetCharge" , 50, -0.3, 0.3);

In my *.plot file for the analysis I have:
# BEGIN PLOT /MC_GENSTUDY_JETCHARGE/WJetCharge$
Title= Jet charge $\times$ W charge  ($Q_j Q_W$)
Stack=.*/MC_GENSTUDY_JETCHARGE/QuarkJetCharge$ .*/MC_GENSTUDY_JETCHARGE/GluonJetCharge$
XLabel=$e^2$
YLabel=$\int f(x) dx \equiv 1$ 
LogY=0
LegendYPos=0.95
LegendXPos=0.60
# END PLOT

This doesn't stack the histograms at all, it just prints each one
individually.  I've tried various combinations of:
> QuarkJetCharge, /MC_GENSTUDY_JETCHARGE/QuarkJetCharge, .*QuarkJetCharge
to no avail.

I expect something like:
http://root.cern.ch/root/html534/tutorials/hist/hstack.C.html

I was also wondering if there was the ability to do something like the
"nostack" option from ROOT, (ie the histogram bins are just drawn on top
of each other, not added together)

Cheers,

    Dave