ArcMapAddinDistanceAndDirection.ViewModels.TabBaseViewModel.IsValid C# (CSharp) Method

        private bool IsValid(System.Windows.DependencyObject obj)
        {
            // The dependency object is valid if it has no errors and all
            // of its children (that are dependency objects) are error-free.
            return !Validation.GetHasError(obj) &&
            System.Windows.LogicalTreeHelper.GetChildren(obj)
            .OfType<System.Windows.DependencyObject>()
            .All(IsValid);
        }