force rendering in more cases

src/tree.c

@@ -342,13 +342,16 @@ void tree_split(Con *con, orientation_t orientation) {
     }
 
     Con *parent = con->parent;
+
+    /* Force re-rendering to make the indicator border visible. */
+    FREE(con->deco_render_params);
+    FREE(parent->deco_render_params);
+
     /* if we are in a container whose parent contains only one
      * child (its split functionality is unused so far), we just change the
      * orientation (more intuitive than splitting again) */
     if (con_num_children(parent) == 1) {
         parent->orientation = orientation;
-        FREE(con->deco_render_params);
-        FREE(parent->deco_render_params);
         DLOG("Just changing orientation of existing container\n");
         return;
     }