layout.signal_track_added.connect(sigc::mem_fun(this, &Layout3D::track_added));
layout.signal_track_removed.connect(sigc::mem_fun(this, &Layout3D::track_removed));
layout.signal_vehicle_added.connect(sigc::mem_fun(this, &Layout3D::vehicle_added));
layout.signal_track_added.connect(sigc::mem_fun(this, &Layout3D::track_added));
layout.signal_track_removed.connect(sigc::mem_fun(this, &Layout3D::track_removed));
layout.signal_vehicle_added.connect(sigc::mem_fun(this, &Layout3D::vehicle_added));