// IN SETUP(), WE ADD ONE LINE OF CODE TO MAKE OUR LISTENER LISTEN TO OUR CURRENT WINDOW this.addMouseWheelListener(new CMouseWheelEvent());
float wheelScalingFactor=1.1;  //magnification factor
class CMouseWheelEvent implements MouseWheelListener {
  public CMouseWheelEvent() {}
  public void mouseWheelMoved(MouseWheelEvent e) {
    int notches = e.getWheelRotation();
    C.pose(); 
    float r=0.5*width/Rbox;  float y=-(10.*notches)/r; 
    C.anchor();
    C.D=C.sD+y;
    C.pullE();  C1.track(C); C2.track(C1);   C2.apply();  
  }
}