if(!c) error((*iter),strprintf(_("Failed to load subcanvas '%s'"), str.c_str()));
if(!layer->set_param(param_name,c))
error((*iter),_("Layer rejected canvas link"));
if(!c) error((*iter),strprintf(_("Failed to load subcanvas '%s'"), str.c_str()));
if(!layer->set_param(param_name,c))
error((*iter),_("Layer rejected canvas link"));