column->pack_start(*ret,true);
//column->add_attribute(ret->property_visible(), model.is_value_node);
column->add_attribute(ret->property_value_desc(), model.value_desc);
column->add_attribute(ret->property_canvas(), model.canvas);
column->pack_start(*ret,true);
//column->add_attribute(ret->property_visible(), model.is_value_node);
column->add_attribute(ret->property_value_desc(), model.value_desc);
column->add_attribute(ret->property_canvas(), model.canvas);