fix do not scroll to index zero when no window in row is focused

src/layout/horizontal.h

@@ -481,8 +481,7 @@ void dual_scroller(Monitor *m) {
 
 		// If no focused client in this row, keep current scroll position
 		if (!root_client && n_row > 0) {
-			root_client = row_clients[0];
-			focus_index = 0;
+			return;
 		}
 
 		// Check if scrolling is needed
@@ -1011,4 +1010,4 @@ monocle(Monitor *m) {
 	}
 	if ((c = focustop(m)))
 		wlr_scene_node_raise_to_top(&c->scene->node);
-}
+}