compositor: add a weston_surface_is_mapped() helper
diff --git a/src/shell.c b/src/shell.c
index ea3d0bf..550184a 100644
--- a/src/shell.c
+++ b/src/shell.c
@@ -633,7 +633,7 @@
 	shsurf->saved_y = es->geometry.y;
 	shsurf->saved_position_valid = true;
 
-	if (es->output)
+	if (weston_surface_is_mapped(es))
 		shsurf->surface->force_configure = 1;
 
 	wl_shell_surface_send_configure(&shsurf->resource,