public FormulaViewModel(FormulaModel model, ImagesModel images, EquationViewModel parent)
        {
            this.model   = model;
            this.formula = model.Formula;
            this.parent  = parent;
            this.images  = images;

            model.PropertyChanged  += ModelOnPropertyChanged;
            images.PropertyChanged += ImagesOnPropertyChanged;
            parent.PropertyChanged += ParentOnPropertyChanged;
        }
        public EquationsViewModel(ModelsEx models)
        {
            this.models = models;
            this.Apply  = new ApplyImageFormulasCommand(this);
            viewModels  = new EquationViewModel[models.NumPipelines];
            for (var i = 0; i < viewModels.Length; ++i)
            {
                viewModels[i] = new EquationViewModel(models, i);
                viewModels[i].PropertyChanged += OnPropertyChanged;
            }

            changesBrush   = new SolidColorBrush(Color.FromRgb(237, 28, 36));
            noChangesBrush = (SolidColorBrush)models.Window.Window.FindResource("FontBrush");
        }