Simplify ShowXamlWindow.

Author: MouriNaruto

NanaBox/Utils.cpp

@@ -335,27 +335,7 @@ int ShowXamlWindow(
     ::ShowWindow(WindowHandle, SW_SHOW);
     ::UpdateWindow(WindowHandle);
 
-    MSG Message;
-    while (::GetMessageW(&Message, nullptr, 0, 0))
-    {
-        // Workaround for capturing Alt+F4 in applications with XAML Islands.
-        // Reference: https://github.com/microsoft/microsoft-ui-xaml/issues/2408
-        if (Message.message == WM_SYSKEYDOWN && Message.wParam == VK_F4)
-        {
-            ::SendMessageW(
-                ::GetAncestor(Message.hwnd, GA_ROOT),
-                Message.message,
-                Message.wParam,
-                Message.lParam);
-
-            continue;
-        }
-
-        ::TranslateMessage(&Message);
-        ::DispatchMessageW(&Message);
-    }
-
-    return static_cast<int>(Message.wParam);
+    return ::MileXamlContentWindowDefaultMessageLoop();
 }
 
 int ShowXamlDialog(