sigc::signal<void,synfig::Layer::Handle,synfig::String> signal_layer_new_description_;
sigc::signal<void,synfig::Canvas::Handle> signal_canvas_added_;
sigc::signal<void,synfig::Canvas::Handle> signal_canvas_removed_;
sigc::signal<void,synfig::Layer::Handle,synfig::String> signal_layer_new_description_;
sigc::signal<void,synfig::Canvas::Handle> signal_canvas_added_;
sigc::signal<void,synfig::Canvas::Handle> signal_canvas_removed_;