message: Remove deleted copy and assignment methods
  These methods would not be inherently unsafe for this class, so better
  to not bother with this restriction.
diff: @@ -11,8 +11,6 @@ public:
  public:
  GameOverDialog();
  - GameOverDialog(const GameOverDialog&) = delete;
  - GameOverDialog& operator=(const GameOverDialog&) = delete;
  ClickCallback& returnToMainMenu() { return mCallback; }
  