Add more implementation for gallery menu

Zennysoft.Game.Ma/src/app/App.cs

@@ -219,6 +219,7 @@ public partial class App : Node, IApp
   private async Task<Node> LoadSceneInternal(string sceneName)
   {
     LoadingScreen.ShowLoadingScreen();
+    MainMenu.Hide();
     LoadingScreen.ProgressBar.Value = 0;
     var sceneLoader = new SceneLoader();
     CallDeferred(MethodName.AddChild, sceneLoader);
@@ -238,11 +239,7 @@ public partial class App : Node, IApp
     OptionsMenu.GameTab.GrabFocus();
   }
 
-  private async void OnGallery()
-  {
-    GalleryMenu.Show();
-    GalleryMenu.ItemButton1.GrabFocus();
-  }
+  private async void OnGallery() => GalleryMenu.Show();
 
   public void OnQuit() => AppLogic.Input(new AppLogic.Input.QuitGame());