PRE { background-color:beige;
      border-color:maroon; border-style:solid; border-width:thin;
      padding:5px; }

Here is the code we want to show.

pdf->plotOn(plot); 
//draw the two separate pdf's
pdf->plotOn(plot, RooFit::Components("bkg_pdf"), RooFit::LineStyle(kDashed) );
pdf->plotOn(plot, RooFit::Components("sig_pdf"), RooFit::LineColor(kRed), RooFit::LineStyle(kDashed) );
plot->Draw();   // to show the RooPlot in the current ROOT Canvas