event: Only consider topmost windows when generating SDL_QUIT

Otherwise, the quit event can be sent prematurely. The topmost status must be queried and cached before sending the close request event, as the window may be destroyed in an event handler.

src/events/SDL_windowevents.c

@@ -228,6 +228,9 @@ bool SDL_SendWindowEvent(SDL_Window *window, SDL_EventType windowevent, int data
         post_event = false;
     }
 
+    // The window might be destroyed in an event handler, so cache the topmost status first.
+    const bool window_is_topmost = !window->parent;
+
     // Post the event, if desired
     SDL_Event event;
     event.type = windowevent;
@@ -301,7 +304,7 @@ bool SDL_SendWindowEvent(SDL_Window *window, SDL_EventType windowevent, int data
         }
     }
 
-    if (windowevent == SDL_EVENT_WINDOW_CLOSE_REQUESTED && !SDL_HasActiveTrays()) {
+    if (windowevent == SDL_EVENT_WINDOW_CLOSE_REQUESTED && window_is_topmost && !SDL_HasActiveTrays()) {
         int count = window ? 0 : 1;
         for (SDL_Window *n = _this->windows; n; n = n->next) {
             if (!n->parent && !(n->flags & SDL_WINDOW_HIDDEN)) {