FoundBindingError.cs

// Found binding error
FrameworkElement element = parent as FrameworkElement;
if (element != null)
{
    var elementAdornerLayer = AdornerLayer.GetAdornerLayer(element);
 
    Adorner[] adorners = elementAdornerLayer.GetAdorners(element);
    if (adorners != null)
    {
        foreach (Adorner a in adorners)
        {
            if (a is BindingErrorBorderAdorner)
                continue;
        }
    }
 
    elementAdornerLayer.Add(new BindingErrorBorderAdorner(element));
}