} else if (event == vtkCommand::MouseWheelForwardEvent && isi->GetInteractor()->GetControlKey()) {
double factor = 2;
this->Dolly(pow((double)1.1, factor),isi->GetInteractor());
Execute(caller, vtkCommand::EndInteractionEvent, NULL);
} else if (event == vtkCommand::MouseWheelBackwardEvent && !isi->GetInteractor()->GetControlKey()) {
} else if (event == vtkCommand::MouseWheelForwardEvent && isi->GetInteractor()->GetControlKey()) {
double factor = 2;
this->Dolly(pow((double)1.1, factor),isi->GetInteractor());
Execute(caller, vtkCommand::EndInteractionEvent, NULL);
} else if (event == vtkCommand::MouseWheelBackwardEvent && !isi->GetInteractor()->GetControlKey()) {