using namespace RooFit ;
void test() 
{
    RooRealVar m("m","m",-10,10);
    RooCategory c("c","c");
    TCanvas *c01 = new TCanvas();
    TH1F *hfix1 = new TH1F("hfix1","hfix1 title",100,-10,10);
    hfix1->Sumw2();
    hfix1->FillRandom("gaus",1000);
    hfix1->Draw();

    TCanvas *c02 = new TCanvas();
    TH1F *hfix2 = new TH1F("hfix2","hfix2 title",100,-10,10);
    hfix2->Sumw2();
    hfix2->FillRandom("gaus",1000);
    hfix2->Draw();

    RooDataHist* dd = new RooDataHist("dd", "dd", m, Index(c),
            Import("hfix1", *hfix1),
            Import("hfix2", *hfix2)
            //,Weight(1./2.)  // this doesn't seem right
            );

    TCanvas *c11 = new TCanvas();
    frame1 = m.frame(Title("hfix1"));
    dd->plotOn(frame1,Cut("c==c::hfix1")
            //,Rescale(0.5)  // this doesn't seem right
            );
    frame1->Draw();
    
    TCanvas *c12 = new TCanvas();
    frame2 = m.frame(Title("hfix2"));
    dd->plotOn(frame2,Cut("c==c::hfix2"));
    frame2->Draw();
};