void on_value_node_replaced(synfig::ValueNode::Handle replaced_value_node,synfig::ValueNode::Handle new_value_node);
void on_canvas_added(synfig::Canvas::Handle canvas);
void on_canvas_removed(synfig::Canvas::Handle canvas);
void on_value_node_replaced(synfig::ValueNode::Handle replaced_value_node,synfig::ValueNode::Handle new_value_node);
void on_canvas_added(synfig::Canvas::Handle canvas);
void on_canvas_removed(synfig::Canvas::Handle canvas);