void ZoomPad()
{
  if(!gPad) return;
  int event = gPad->GetEvent();
  TVirtualPad* p = gPad->GetSelectedPad();
  if(event==53 && p){
    TList* l = p->GetListOfExecs();
    if(l && !(l->FindObject("zoomer")))
      p->AddExec("zoomer","ZoomPad()");
    return;
  }
  if(event != 61) return;
  TObject* o = gPad->GetSelected();
  if(!o) return;
  cout<<gPad->GetName()<<" "<<event<<" ";
  if(o) cout<<o->GetName()<<" ";
  if(p) cout<<p->GetName()<<" ";
  cout<<endl;
  
  TObject* clone = 0;
  Option_t* drawoption = "";
  if(o->InheritsFrom(TH1::Class()) || o->InheritsFrom(TGraph::Class()) ||
     o->InheritsFrom(TF1::Class()) ){
    clone = o->Clone();
    drawoption = o->GetDrawOption();
  }
  else if(!p->InheritsFrom(TCanvas::Class())){
    TPad* clonep = (TPad*)(p->Clone());
    clonep->SetPad(0,0,1,1);
    clone = clonep;
  }
  if(clone){
    clone->SetBit(TObject::kCanDelete,true);
    TCanvas* c = new TCanvas;
    c->cd();
    clone->Draw();
    c->AddExec("zoomer","ZoomPad()");
    gPad->cd();
  }  
  
}

void zoomer()
{
  new TCanvas;
  c1->Divide(2,2);
  c1->cd(1);
  TH1F* h[3];
  for(int i=0; i<3; ++i){
    char name[20];
    sprintf(name,"h%d",i);
    h[i] = new TH1F(name,name,10,0,10);
    c1->cd(i+1);
    h[i]->FillRandom("pol0",10);
    h[i]->SetLineColor(i+1);
    h[i]->Draw();
  }
  double x[] = {1,2,3,4,5};
  double y[] = {3,6,8,1,5};
  TGraph* g = new TGraph(5,x,y);
  c1->cd(4);
  g->Draw("alp");
  c1->AddExec("zoomer","ZoomPad()");
  c1->Update();

}