Update exit menu item to hide window on click

Changed the exit menu item's click handler to hide the current window instead of destroying all windows via the window manager. This simplifies the exit logic and ensures only the relevant window is closed.

Author: lijy91

examples/window_example/main.cpp

@@ -282,12 +282,11 @@ int main() {
     // Add exit item
     auto exit_item = std::make_shared<MenuItem>("Exit", MenuItemType::Normal);
     exit_item->AddListener<MenuItemClickedEvent>(
-        [&window_manager](const MenuItemClickedEvent& event) {
+        [window_ptr](const MenuItemClickedEvent& event) {
           std::cout << "Exit clicked from context menu" << std::endl;
-          // Get all windows and destroy them to trigger app exit
-          auto windows = window_manager.GetAll();
-          for (auto& window : windows) {
-            window_manager.Destroy(window->GetId());
+          // Close the window to trigger app exit
+          if (window_ptr) {
+            window_ptr->Hide();
           }
         });
     context_menu->AddItem(exit_item);