/// <summary>
        ///     Adds a new higher unit.
        /// </summary>
        /// <returns>The new <see cref="HigherUnitDecorator" />.</returns>
        public IUnitDecorator AddNewHigherUnit()
        {
            HigherUnitDecorator higherUnit = this._decoratorService.Decorate(new HigherUnit());

            AddSubordinate(higherUnit);

            return(higherUnit);
        }
        /// <summary>
        ///     Adds a new <see cref="HigherUnit" /> to the root unit's list of subordinates.
        /// </summary>
        public void AddNewHigherUnit()
        {
            HigherUnitDecorator higherUnit = this._decoratorService.Decorate(new HigherUnit());

            higherUnit.PropertyChanged += OnHigherUnitDecoratorPropertyChanged;

            RootUnit.AddSubordinate(higherUnit);
            SelectedUnit = higherUnit;
        }