#ifndef TRAINPANEL_H_
#define TRAINPANEL_H_
+#include <sigc++/trackable.h>
#include <msp/gltk/hslider.h>
#include <msp/gltk/label.h>
#include <msp/gltk/panel.h>
class Engineer;
-class TrainPanel: public Msp::GLtk::Panel
+class TrainPanel: public Msp::GLtk::Panel, public sigc::trackable
{
private:
Engineer &engineer;