SDL: emscripten: find the right SDL_Window during fullscreen events.

SDL Commits
1 
From deb85d1fa899a76c1c212e3e7129259176d8d26a Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Mon, 15 Dec 2025 12:08:01 -0500
Subject: [PATCH] emscripten: find the right SDL_Window during fullscreen
 events.

Fixes #14629.
---
 src/video/emscripten/SDL_emscriptenevents.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/video/emscripten/SDL_emscriptenevents.c b/src/video/emscripten/SDL_emscriptenevents.c
index 7f0c39c0866ba..90e63c8a19064 100644
--- a/src/video/emscripten/SDL_emscriptenevents.c
+++ b/src/video/emscripten/SDL_emscriptenevents.c
@@ -497,10 +497,21 @@ static EM_BOOL Emscripten_HandleFullscreenChange(int eventType, const Emscripten
 static EM_BOOL Emscripten_HandleFullscreenChangeGlobal(int eventType, const EmscriptenFullscreenChangeEvent *fullscreenChangeEvent, void *userData)
 {
     SDL_VideoDevice *device = userData;
-    SDL_Window *window = Emscripten_GetFocusedWindow(device);
+    SDL_Window *window = NULL;
+    for (window = device->windows; window != NULL; window = window->next) {
+        const char *canvas_id = window->internal->canvas_id;
+        if (*canvas_id == '#') {
+            canvas_id++;
+        }
+        if (SDL_strcmp(fullscreenChangeEvent->id, canvas_id) == 0) {
+            break;  // this is the window.
+        }
+    }
+
     if (window) {
         return Emscripten_HandleFullscreenChange(eventType, fullscreenChangeEvent, window->internal);
     }
+
     return EM_FALSE;
 }