Display instance (if present) in nested layouts

sway/border.c

@@ -254,7 +254,9 @@ static char *generate_container_title(swayc_t *container) {
 		swayc_t* child = container->children->items[i];
 		const char *title = NULL;
 		if (child->type == C_VIEW) {
-			title = child->app_id ? child->app_id : (child->class ? child->class : "(null)");
+			title = child->app_id ? child->app_id :
+				(child->instance ? child->instance :
+				(child->class ? child->class :"(null)"));
 		} else { //child->type == C_CONTAINER
 			title = generate_container_title(child);
 		}