TFile *f1 = TFile::Open("hsimple.root");
TIter keyList(f1->GetListOfKeys());
TKey *key;
TCanvas c1;
c1.Print("hsimple.ps[");
while ((key = (TKey*)keyList())) {
   TClass *cl = gROOT->GetClass(key->GetClassName());
   if (!cl->InheritsFrom("TH1")) continue;
   TH1 *h = (TH1*)key->ReadObj();
   h->Draw();
   c1.Print("hsimple.ps");
}
c1.Print("hsimple.ps]");