SDL: Add window title to app_ids for different

SDL Commits
1 
From 39eab4bf44472790dddf02490ac260f810c30c9a Mon Sep 17 00:00:00 2001
From: "Lei.Huang" <[EMAIL REDACTED]>
Date: Mon, 5 Dec 2022 10:28:31 +0800
Subject: [PATCH] Add window title to app_ids for different

"app_ids" can be used for multiple windows

Signed-off-by: Lei.Huang <leihuang@amd.com>
---
 src/video/wayland/SDL_waylandwindow.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/video/wayland/SDL_waylandwindow.c b/src/video/wayland/SDL_waylandwindow.c
index b684489bd391..907224710212 100644
--- a/src/video/wayland/SDL_waylandwindow.c
+++ b/src/video/wayland/SDL_waylandwindow.c
@@ -1270,7 +1270,11 @@ void Wayland_ShowWindow(_THIS, SDL_Window *window)
             }
         } else {
             data->shell_surface.xdg.roleobj.toplevel = xdg_surface_get_toplevel(data->shell_surface.xdg.surface);
-            xdg_toplevel_set_app_id(data->shell_surface.xdg.roleobj.toplevel, c->classname);
+            if (c->classname != NULL) {
+                xdg_toplevel_set_app_id(data->shell_surface.xdg.roleobj.toplevel, c->classname);
+            } else {
+                xdg_toplevel_set_app_id(data->shell_surface.xdg.roleobj.toplevel, window->title);
+            }
             xdg_toplevel_add_listener(data->shell_surface.xdg.roleobj.toplevel, &toplevel_listener_xdg, data);
         }
     }