TH1, TGraphErrors: line width of error boxes with option E2

ROOT
1

Hello,
is it possible to vary the width of the line of the error boxes produced when drawing a TH1 (or a TGraphErrors) with option E2 (or 2)? I was expecting this width to be settable with SetLineWidth, but it does not work.

Cheers,
Andrea

2 
{
   TH1F *hpx__1 = new TH1F("hpx__1","This is the px distribution",10,-4,4);
   hpx__1->SetBinContent(0,1);
   hpx__1->SetBinContent(1,1);
   hpx__1->SetBinContent(2,1);
   hpx__1->SetBinContent(3,1);
   hpx__1->SetBinContent(4,1);
   hpx__1->SetBinContent(6,1);
   hpx__1->SetBinContent(7,2);
   hpx__1->SetBinContent(8,4);
   hpx__1->SetBinContent(9,4);
   hpx__1->SetBinContent(10,5);

   hpx__1->SetFillStyle(0);

   hpx__1->SetLineColor(ci);
   hpx__1->SetLineWidth(3);
   hpx__1->Draw("E2");
}